Glossary of astronomy

2824: 6990: 333: 12152: 5438: 7688: 3951: 10518: 9443: 9303: 3399: 16735: 13638: 16747: 1828: 9014: 8705:, which can be difficult to continuously track because of their size and great distance from Earth. Very short observation arcs, e.g. where the time between the initial observation and the most recent observation is less than 30 days, are of limited descriptive power because they represent only a very small fraction of the total path traced by the object in its 1492: 13617:, and is useful in specifically identifying small bodies observed before and after planetary encounters, as its numerical value remains largely constant throughout the body's lifetime. It is also used to distinguish between different kinds of orbits which are characteristic of different classes of bodies. 12446:

that has an anomalously high rate of star formation. The criteria for a starburst is a star formation rate that would normally consume the galaxy's available supply of unbound gas within a time period shorter than the age of the galaxy. Most starbursts occur as a result of galactic interactions, such

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that is observed to vary in brightness. This variation may be periodic, with one or more cycles that last hours, days, months, or even years. Some stars vary in an irregular manner, while others undergo cataclysmic changes in brightness. Other forms of variability are intrinsic changes to the star's

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The time period immediately before sunrise and after sunset during which, despite the Sun being completely below the horizon, the scattering of sunlight by the Earth's atmosphere supplies significant illumination to the ambient environment. Several definitions of twilight are commonly distinguished,

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which appear near each other on the celestial sphere, either because the two stars coincidentally lie along nearly the same line of sight from the Earth, though they are in fact physically distant from each other, or because the two stars are actually located in physical proximity to each other, by

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The human eye as used without any magnifying or light-collecting optical aid, such as a telescope, nor any eye protection. Many astronomical objects emit or reflect visible light that is sufficiently bright to fall within the limits of normal human visual perception, allowing observers to see them

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A branch of astronomy that uses analytical and computational models based on principles from physics and chemistry to describe, explain, and model the properties of astronomical objects and phenomena, with the ultimate goal of accurately predicting the observable or testable consequences of those

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between the Sun and the Earth. Because all three bodies are continuously moving, the shadow of the Moon traces out a narrow path across the Earth's surface, and from any given location within or very close to this path, the eclipse is visible only for a short duration. Depending on the observer's

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that are cooler and less massive. The term originated from historical stellar models that assumed stars began their early life at a high temperature then gradually cooled off as they aged. It may be used to refer to the higher-temperature members of any particular population or category of stars,

325:) to 1 (indicating total reflection). The albedo reported for an astronomical body may vary widely by the spectral and angular distribution of the incident radiation, by the "layer" of the body being measured (e.g. upper atmosphere versus surface), and by local variation within these layers (e.g. 3705:

and change over time. The primary use of astronomical quantities specified by epochs is to calculate other relevant parameters of motion in order to predict future positions and velocities. In modern usage, astronomical quantities are often specified as a polynomial function of a particular time

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A grid of fine lines or crosshatches engraved upon a transparent glass plate, which when placed in front of film during a photographic exposure produces a corresponding grid in the resulting photograph by creating permanent shadows on the film negative. These grids are used in some photographic

6340:, which is a plot of stars having the same mass but differing ages. In fact, multiple evolutionary tracks can be used to build isochrones by putting curves through equal-age points along the tracks. When the mass of a star can be determined, an isochrone can be used to estimate the star's age. 10836: 3605: 1326:

A gaseous envelope held in place by the gravity of a planet. This shell of gas has no clearly defined exterior boundary, but instead grows increasingly tenuous with altitude. The term can also be applied to a stellar atmosphere, referring to the visible outer layers of a

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is not an accurate representation of the body's actual orbit. Perturbing forces may include the gravitational forces exerted by any number of additional bodies, the off-center gravitational forces which are consequences of bodies not being perfectly spherical, and/or

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A type of elementary particle, electrically neutral and with an extremely small rest mass, that interacts with other particles only via the weak interaction and the gravitational interaction. Neutrinos therefore typically pass through normal matter unimpeded and

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and other elements. Because O-type stars have relatively short lifetimes (typically a few million years), the presence of an H II region indicates that massive star formation has taken place recently at that location. H II regions are often found in the arms of

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The minimum speed that must be achieved for a free, non-propelled object to escape from the gravitational influence of a massive body, i.e. to achieve an infinite distance from it; more generally, escape velocity is the speed at which the sum of an object's

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23.4 degrees with respect to the ecliptic. To an observer on Earth, this means that the path the Sun appears to follow upon the celestial sphere is not a straight line (i.e. the ecliptic does not appear "flat"). Twice during each complete orbit, at the two

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in the Northern Hemisphere, is the annual date featuring the longest duration of daylight and the shortest duration of nighttime for any given point in the Northern Hemisphere; the reverse is true in the Southern Hemisphere, where the June date is the

6974:). There are also intermediate phases, during which the visible side may be only partially sunlit, e.g. when the Moon appears as a crescent. During the part of the lunar cycle in which the illuminated portion is growing larger, the Moon is said to be 10529:

when its position as viewed from Earth is at a right angle to the direction of the Sun. In such cases the moon or planet appears to be in its quarter phase (or nearly so), where half of the body is illuminated by the Sun and the other half is in

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positioned at a focal point of each ellipse. The word "orbit" can variously refer to the elliptical trajectory itself or the act of following this trajectory, and can refer to a stable, regularly repeating trajectory as well as a non-repeating

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at which a smaller object will maintain a constant position relative to the larger bodies. At other locations, a small object would eventually be pulled into its own orbit around one of the large bodies, but at the Lagrangian points the

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all align in a way that causes the small object to become "locked" in a stable or nearly stable relative position. For each combination of two orbital bodies, there are five such Lagrangian points, typically identified with the labels

12534:, located above the stellar core, radiation zone, and convection zone. Although it constitutes only a small portion of the star's mass, for some evolved stars the stellar envelope can encompass a significant fraction of the radius. 8887:

The positioning of two celestial objects on opposite sides of the sky, from the perspective of an observer. This occurs, for example, when a planet makes its closest approach to the Earth, placing it in opposition to the

7112:, where the lower the value, the brighter the object. By convention, a first magnitude star is 100 times as bright as a sixth magnitude star. Magnitude 6 is considered the lower limit of objects that can be seen with the 6456:(or sometimes a straight line) in three-dimensional space. Kepler orbits are idealized mathematical constructions which consider only the point-like gravitational attraction of two bodies, neglecting more complex orbital 953:

A field that studies the geology of solidified bodies such as the planets and their moons, asteroids, comets, and meteorites. Investigations are centered around the composition, structure, processes, and history of these

11651:, in which a portion of the Earth passes through the shadow cast by the Moon, temporarily blocking sunlight, fully or partially, from reaching that portion of the Earth's surface. A solar eclipse occurs when the Moon is 10710:

point and extends toward the higher luminosity and lower temperature range until reaching the red-giant tip. This branch consists of older stars that have evolved away from the main sequence but have not yet initiated

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seconds each. Because these are units of constant duration, the Julian year is also constant and does not vary with a specific calendar or with any of the other means of determining the length of a year, such as the

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as a bright glow surrounding the lunar disk. The temperature of the corona is much higher than that of the stellar surface, and the mechanism that creates this heat remains subject to debate among astronomers.

11590:) on consecutive days. Because the Earth's orbit around the Sun affects the angle at which the Sun is seen from the Earth, the Sun appears to take slightly longer to return to the same position than do the 7668:

and is estimated to contain 100–400 billion stars and at least that number of planets. The Solar System is located on the inner edge of one of the Milky Way's spiral arms, about 27,000 light-years from the

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The Earth's atmosphere permits certain wavelengths of electromagnetic energy to pass through but reflects or absorbs others, making it difficult or impossible to detect them from the surface. As a result,

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between the orbital periods of two planets (small bodies), both of which are orbiting a large central star. The inner planet completes two revolutions in the time it takes the outer planet to complete one.

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of gas will begin to undergo collapse and form stars. A cloud can become unstable against collapse when it cools sufficiently or has perturbations of density, allowing gravity to overcome the gas pressure.

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Rodono, M.; et al. (September 1986), "Rotational modulation and flares on RS CVn and BY Dra-type stars. I - Photometry and SPOT models for BY Dra, AU Mic, AR Lac, II Peg and V 711 Tau (= HR 1099)",

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The quantity of some specified particle or object class per unit volume. For atoms, molecules, or subatomic particles, the volume is typically in cm or m. With stars, cubic parsecs (pc) are often used.

3792:, and a right-handed convention. This system is widely used to specify the positions of celestial objects as viewed from Earth. It may be implemented in either spherical or rectangular coordinates. 1200:, and their appearance in scientific literature has become increasingly infrequent. Exceptions include the symbols for the Sun (☉), the Earth (🜨), and the Moon (☾), which are sometimes used for 8133:. Because these four extrasolar messengers are created by different astrophysical processes, their presence or absence during a celestial event can reveal useful information about their sources. 9673:

or angle between an orbiting body and the Sun as viewed from a particular perspective, such as the Earth. It determines the amount of a planet or moon's visible surface that lies in shadow.

9342:, or its speed relative to the center of mass of the most massive body in the system. The term may be used to refer to either the mean orbital speed, i.e. the average speed over the entire 5878:

at a ground observer's particular location, the concept of the hour circle is employed to describe the longitudinal position of a celestial object relative to the observer's local meridian.

1562:, the barycenter may actually be located within the radius of the star, such that the planet appears to orbit the star itself, though both bodies actually orbit the shared barycenter. 5222:

or to the position of an observer, i.e. as defined by a straight line between the center of the Earth (or the observer) and the object at a given time, without any corrections for

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and a vast region of space beyond it. Its outer limit is often considered the boundary between matter originating from the Sun and matter originating from the rest of the galaxy.

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The apparent boundary between the surface of a celestial body and its sky when viewed from the perspective of an observer on or near that body's surface; more specifically, the

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within its core. Astronomers can determine the mass, age, platemperature, chemical composition, and many other properties of a star by observing its motion through space, its

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For a variable star, this is the highest amplitude achieved during a rise in luminosity, followed by a decline. This data point can provide useful distance information for a

184:

star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times

5202:) disk with the same cross-section. It is a measure of how much of the incoming illumination is being scattered back toward an observer and has a value between zero and one. 10948:

matches an orbiting body's gravitational self-attraction. Inside this limit, the tidal forces will cause the orbiting body to disintegrate, usually to disperse and form a

6851:. The angle is typically measured eastwards from the reference direction to the ascending node (i.e. counterclockwise as seen from the north). It is one of six canonical 2317:

or share a common origin, or they are known to be gravitationally bound (in which case their proper motions may be rather different but average to be the same over time).

884:

An interdisciplinary field that studies the origins, evolution, distribution, and future of living systems in the universe, encompassing research on organic compounds in

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and has since undergone internal melting to produce an interior of non-uniform composition. Protoplanets represent an intermediate step in the formation of a full-sized

7290:, the mean anomaly does not correspond to a real geometric angle but is instead a contrived parameter used to make calculating the position of the orbiting body in the 7455:

by collisions with air molecules in the upper atmosphere, leaving an ionization trail as a result of its rapid motion and sometimes also shedding material in its wake.

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that is illuminated by direct sunlight as viewed from Earth. This shape is referred to as a phase because it gradually changes in a regular cycle over the course of a

14096:. Since most absorption lines are caused by elements other than hydrogen and helium—what astronomers refer to as "metals"—these are sometimes called metal weak stars. 13391:

galaxy where the spiral arms are found and where most of the star formation takes place. It is about 300–400 parsecs (980–1,300 light-years) deep and centered on the

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on consecutive nights. The Earth's sidereal day is equal to approximately 86,164.09 seconds (23 hours, 56 minutes, 4.09 seconds), about four minutes shorter than the

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The main physical body of a gravitationally bound, multi-object system. The primary constitutes most of the system's mass and is generally located near the system's

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and the other known planets, such that it appears to be "detached" from the rest of the Solar System. Detached objects are thus distinct from other populations of

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over the course of one day. Diurnal motion is caused by Earth's rotation about its own axis, such that every object appears to follow a circular path called the

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surrounding a specific and identifiable grouping of stars. The names of constellations are assigned by tradition and often have an associated folklore based in

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A concentration of mass formed out of the contraction of a collapsing interstellar cloud. Once sufficient mass has fallen onto this central core, it becomes a

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Bychkov, V. D.; et al. (April 2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars",

6193:. This effect causes more distant objects such as stars to appear redder and dimmer than expected. It is not to be confused with the separate phenomenon of 2416:

as observed from a third body (usually the Earth), such that, from the observer's perspective, the objects appear to closely approach each other in the sky.

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A list of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery.

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as they pass in front of their host stars. A transit by an object that appears roughly the same size or larger than the body it is transiting is called an

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A concentration of mass so compact that it creates a region of space from which not even light can escape. The outer boundary of this region is called the

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The process of separating out different constituents of a planetary body, causing it to develop compositionally distinct layers (such as a metallic core).

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which are so distant from observers on Earth that they do not appear to move relative to each other, as opposed to the "foreground" of objects within the

16777: 14394: 8693:, which defines the length of the path traced by the object between these same observations. The term is primarily used in the discovery and tracking of 8638:

which are not gravitationally bound to each other, but move together through space in a loose association. The OB in the name is a reference to stars of

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from the Earth's surface without any special equipment. Vision corrected to normal acuity using eyeglasses or contact lenses is still considered unaided.

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2. The hazy band of light itself, which from Earth appears as a band because the galaxy's disk-shaped structure is viewed side-on from within.

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away from the body. It is a dimensionless quantity typically measured on a scale from 0 (indicating total absorption of all incident radiation, as by a

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and flowing outwards at up to 900 kilometres per second (2,000,000 mph) into interplanetary space. Phenomena influenced by the solar wind include

11401:), measured as the time it takes for the fixed stars, as viewed from a particular point on the object's surface, to return to the same position in the 2230:. Because the energy output of a star varies by frequency as a function of temperature, the color index can be used to indicate the star's temperature. 2342:

with a very high mass relative to its radius, compared to most ordinary atomic matter. The term typically refers to very high-density objects such as

1863:; this means that the path of the Sun, as viewed from Earth, appears to move both above and below the celestial equator during the course of the year. 16665: 13155:

as observed from Earth, but can in principle be calculated with respect to the sky as observed from any body. It is related to but distinct from the

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2. An astronomical event during which a celestial body or object passes visibly across the face of a much larger body. An example is the

11206:(or any other distant luminous object) as viewed through a medium, such as the Earth's atmosphere, caused by the passing of light through layers of 13283:

on the spectra of other stars. For example, water vapor in the atmosphere creates significant telluric absorption bands at wavelengths above 6800

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A broken arc of illuminations seen at the limb of very young or very old lunar crescents. The visual similarity to the moments before and after a

16672: 11962:, as viewed from a given location on the Earth's surface. Because the duration of this interval changes during the Earth's orbit around the Sun, 8857:

A measure of the resistance of a medium to the radiative transmission of energy. Within a star, it is an important factor in determining whether

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within an astronomical object. Note that this definition includes elements that are not traditionally considered metallic by chemical convention.

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that display pulsation frequencies of two different classes of variables. An example are variables displaying characteristic frequencies of both

1780:. The focus remains stationary as the telescope is re-oriented, which is advantageous for the stable mounting of heavy spectroscopic instruments. 1598:. It depicts a starting condition of extremely high density and temperature, followed by an ongoing expansion that led to the current conditions. 10345:

The rate of angular motion of an object over an interval of time, usually years. For stars, this is typically given in milliarcseconds per year.

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that emits a beam of electromagnetic radiation. This beam is observed only when it is pointing toward Earth, making the object appear to pulse.

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telescopes to produce reference markers in photographs of distant stars, allowing precise and convenient measurement of astrometric positions.

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are caused by the visible side of the Moon being alternately illuminated by sunlight and immersed in shadow during its orbit around the Earth.

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Rufener, F.; Bartholdi, P. (June 1982), "List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry",

11578:, measured as the time it takes for the Sun, as viewed from a particular point on the Earth's surface, to return to the same position in the 10614:. Positive values are used to indicate a receding object. An object such as a star can undergo changes in its radial velocity because of the 14336:

A band of light in the night sky, thought to be sunlight reflected from cometary dust concentrated in the plane of the zodiac, or ecliptic.

11435:, e.g. the Earth's orbital period around the Sun. The name "sidereal" implies that the object returns to the same position relative to the 493:

A measure of the brightness of a celestial body as seen by an observer on Earth, adjusted to the value it would have in the absence of the

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of the ellipse. The true anomaly is one of three angular parameters that define a position along an orbital path, the other two being the

7896:, only one side of the Moon is ever visible from the Earth. Sunlight reflected from its surface makes the Moon appear very bright in the 15009:

The large scale structure of the universe; Proceedings of the Symposium, Tallinn, Estonian SSR, September 12-16, 1977. (A79-13511 03-90)

9264:, etc., or any combination thereof) exist in some definite mathematical relationship with each other. Most commonly, the term refers to 16006: 11316:

system or star–planet system. When the distance between the orbiting bodies is unknown, the semi-major axis may be given as an angle.

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that had the visual appearance of a galaxy with a particularly bright, star-like nucleus. As a group, they are intermediate between

252:. The material is acquired from a source external to the central object, and friction causes it to spiral inward towards the object. 5703:

allows its age to be estimated. Stars of similar types are also found grouped together in specific regions of the chart, including

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Silaj, J.; Jones, C. E.; Tycner, C.; Sigut, T. A. A.; Smith, A. D. (March 2010), "A Systematic Study of Hα Profiles of Be Stars",

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around a planet. Though the smaller body is often said to orbit the larger body itself, both bodies actually follow approximately

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is hidden by another, nearer body or object that passes between it and the observer, thereby blocking the first object from view.

1135:. Though the terms astronomical "object" and astronomical "body" are often used interchangeably, there are technical distinctions. 16384: 14952:

Forbes, John C.; Loeb, Abraham (February 2019), "On the Existence of Brown Dwarfs More Massive than the Hydrogen Burning Limit",

13397:. Stars belonging to this population generally follow orbits that lie close to this plane. This is in contrast to members of the 3759: 3465: 11602:. The length of the solar day is also not constant, but rather changes over the course of the year because the Earth's orbit is 8614:

values over time, showing how observed data differ from theoretical values which have been calculated according to a particular

17034: 14513: 8199:. Thus, where the zenith is directly above an observer, the nadir is underfoot. The zenith and nadir form the two poles of the 7561:

that has survived its passage through the atmosphere to reach the surface of a planet or moon, usually ranging in size from 50

5840:, the hour angle is one of many ways commonly used to specify the longitudinal position of an object upon the celestial sphere. 3974: 1231:

around the Sun, the astronomical unit is now more rigidly defined as exactly 149,597,870.7 kilometres (92,956,000 miles; 4.8481

661:(in geocentric and heliocentric orbits) or at which the orbiting object moves away from the observer (in orbits outside of the 2561:

or has fallen on Earth, generally composed of fine particles of solid matter far smaller than those found in terrestrial dust.

16957: 16952: 15514: 14404: 6187:

An effect produced by the incremental absorption and scattering of electromagnetic energy from interstellar matter, known as

3028:(in geocentric and heliocentric orbits) or at which the orbiting object moves toward the observer (in orbits outside of the 14426: 8841:

and a spherical outer Oort cloud. The outer limit of the Oort cloud is often considered the cosmographical boundary of the

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are measured in positive degrees from 0° to 90°, while coordinates to the south are measured in negative degrees. See also

13143:. Synodic period is most commonly used to indicate the elapsed time between a given body's consecutive appearances in the 3542:

shape and a smooth, nearly featureless appearance. They are one of three main morphological classes of galaxy, along with

16874: 16829: 12164:

instruments are often placed in orbit, above the atmosphere, where detection of all parts of the spectrum is uninhibited.

9348:, or the instantaneous speed at a particular point in the orbit. Maximum instantaneous orbital speed typically occurs at 7623:. Detecting microvariability typically requires a sufficient number of observations to rule out random error as a source. 14477:

Noyes, R. W.; et al. (April 15, 1984), "Rotation, convection, and magnetic activity in lower main-sequence stars",

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and gases which are stripped from gas clouds and star clusters because of interaction with the gravitational field of a

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that originated in outer space and survived its passage through the atmosphere to reach the surface of a planet or moon.

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A unit of length used to express astronomical distances that is equivalent to the distance that an object moving at the

2610:. Collisions of cosmic rays with the Earth's atmosphere can produce dramatic effects both in the air and on the surface. 1381:. The phenomenon is similar to but much larger in magnitude than other changes in the alignment of Earth's axis such as 17059: 16999: 16972: 15660: 15633: 15575: 15475: 15420: 15321: 15107: 14777: 14647: 14567: 14434: 9987:, with the aim of understanding their formation, composition, topography, dynamics, and interactions with other bodies. 15174:

Miller, J. S. (December 1981), "The galaxy components of BL Lacertae objects, N systems, and quasi-stellar objects.",

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equals 2/3), or approximately 695,700 kilometres (432,300 mi). It is commonly used to express the radii of other

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whose internal strength is dominated by self-gravity and whose orbital dynamics are not significantly affected by gas

10100:

Any solid object (generally larger than 1 kilometre (0.62 mi) in diameter) that arises during the formation of a

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such that, to an observer on Earth's surface, the orbiting object appears motionless, in a fixed position in the sky.

16924: 16884: 16809: 15744: 15294: 15046: 14852: 14740: 14461: 12599: 2004: 17: 9628:

The complex motion of an astronomical body that is subject to forces other than the gravitational attraction of its

1960:, i.e. the two points in the sky that are directly overhead the terrestrial North and South Poles, around which all 17095: 16994: 16912: 16907: 16503: 14361: 12205:

as they would appear from a particular date, time, and location on Earth. It relies on the mathematical methods of

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An imaginary plane that is perpendicular to the line of sight. Typically this is used as a reference plane for the

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that cannot be individually distinguished by the naked eye. The Milky Way Galaxy has a diameter of 100,000–200,000

6136: 14907:

Sánchez Arias, J. P.; et al. (January 2017), "Asteroseismology of hybrid δ Scuti-γ Doradus pulsating stars",

8428:, but with a radius of only 12 km (7.5 mi), making them among the densest known objects in the universe. 7034:. A MACHO is a body that emits little or no radiation and drifts through interstellar space unassociated with any 5752:. It is computed with respect to the next most gravitationally attractive object, such as the nearest star or the 2168:. Schröder et al. (2009) divide solar-type stars into four groups depending on their activity index: very active ( 1469:

An angular measurement of an object's orientation along the horizon of the observer, relative to the direction of

16321: 14711: 14351: 13131:

The time it takes for a body visible from another body (often the Earth) to complete a cycle with respect to the

12980:, including that produced by the effects of rotation. It is typically expressed in units of acceleration such as 11351:

of the Earth begins to tilt away from the Sun, and typically occurs on or near September 22 each year. It is the

11220:, since light rays near the horizon must travel longer paths through the atmosphere before reaching the observer. 8422:

with no electrical charge. Typically, neutron stars have a mass between about 1.35 and 2.0 times the mass of the

6820: 5643: 4858:. Galaxies may contain hundreds of billions of stars and are categorized according to their visual morphology as 4198:. These field stars are important to identify in order to prevent them from contaminating the results of a study. 3903:

is equal to zero. It is a function of the mass of the body and of the distance between the object and the body's

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Universe, whose spatial extent is unknown because it is not directly measurable; this is distinguished from the

10610:

The velocity of an object along the line of sight to the observer, which in astronomy is usually determined via

5319:, such that the orbiting object appears to return to exactly the same position in the sky after a period of one 1365:

over a cycle of approximately 25,772 years, which is caused predominantly by the gravitational influence of the

362:

A large area on the surface of a reflecting object that shows a significant contrast in brightness or darkness (

17085: 15999: 15877: 15548: 15268: 6408: 3900: 15219:

The Light-Time Effect in Astrophysics, Proceedings of ASP Conference Series, held in Brussels 19-22 July 2004.

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The angle at the position of an observer subtended by the equatorial radius of the Sun, the Moon, or a planet.

3435:, the Sun's path appears to intersect the celestial equator, though the two planes are never in fact coplanar. 1192:. Many of these symbols were commonly used historically, though in the modern era they are usually limited to 17054: 17044: 16869: 16864: 16607: 14120:

process with its constituent atoms, so the object's energy output normally comes from radiative cooling. See

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which are left over from the formation process. There is no precise distinction between a planetesimal and a

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in the same time it takes Neptune to complete three. Resonance may act on any time scale, from short-term to

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through the coordinated observation and interpretation of four disparate classes of "messenger" signals with

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being emitted from the star system, as the orbiting debris re-radiates the star's energy into space as heat.

1422:

The angle between an object's rotational axis and its orbital axis, or, equivalently, the angle between its

16919: 16879: 16273: 15036: 12066:

is either 90 degrees or 270 degrees. The solstices occur on or near June 20 and December 21 each year. The

10331:. The actual separation of the two objects depends on the angle of the line between the two objects to the 10173: 5457: 3746: 2262: 15813:

Yuan, Feng; Narayan, Ramesh (September 2004), "On the Nature of X-Ray-Bright, Optically Normal Galaxies",

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of the Earth begins to tilt toward the Sun, and typically occurs on or near March 20 each year. It is the

3359:. Hence, the position of the Sun as viewed from the Earth defines the intersection of this plane with the 2598:

and atomic nuclei which move through space at nearly the speed of light, and which may originate from the

16967: 16962: 16859: 16844: 13165:) and the body from which it is being observed (e.g. Earth) are independently orbiting a third body (the 12605:

1. The region within the volume of a star that transports energy from the stellar core to the

11030: 10815: 10290: 10226: 7711: 7013: 4591: 2565: 1478: 11658:

location and on the apparent sizes of the solar and lunar disks in the sky, an eclipse may appear to be

10620:

of another body, or because of radial pulsations of its surface. The latter, for example, occurs with a

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which results from the combined effects of small, short-term variations. Nutation is distinguished from

7591:, usually weighing less than one gram. If it survives to reach a planetary surface, it is then termed a 1966:

appear to revolve during the course of a day. The celestial poles form the north and south poles of the

17019: 16989: 16750: 16658: 16440: 16232: 15736: 14356: 14200: 14113: 12965: 12263: 6741:-scale distances in non-specialist publications, the unit of length most commonly used in professional 5535:

from these hot stars ionize gas in the surrounding environment, and the nebular gas shines brightly in

4606: 3440: 2823: 2641: 2207: 15760:

Pace, G.; et al. (April 2003), "The Wilson-Bappu effect: A tool to determine stellar distances",

15491: 13097:. As it does on Earth, an object's synodic day may change slightly in duration over the course of the 5290:

are often placed in geostationary orbit so that antennas on Earth do not have to rotate to track them.

3452:

commonly used to specify the apparent positions, orbits, and axial orientations of objects within the

3089:

is so distant that the object is only moderately or weakly affected by the gravitational influence of

1310:(rather than the positions or motions of objects in space, which is more specifically the emphasis of 16679: 16496: 16461: 16454: 16301: 15992: 15543:, Space Telescope Science Institute Symposium, vol. 12, Cambridge University Press, p. 97, 13802: 12981: 12143: 11623:(averaged over the Earth's orbital period) is currently equal to 86,400 seconds, or exactly 24 hours. 11179: 10662: 10332: 9914: 9240:

bodies exert regular, periodic gravitational influences on each other such that one or more of their

8114: 8089: 4882:

are between 1,000 and 3,000 parsecs (3,300 and 9,800 ly) in diameter though some, including the

3982: 3876:

the equator, and the durations of day and night are approximately equal all over the planet. Compare

3519: 15676:

Heller, R.; et al. (April 2011), "Tidal obliquity evolution of potentially habitable planets",

13695:, which was visible from Earth in 2004 and 2012. Because a transit results in a decrease in the net 9299:, and often leads to either long-term stabilization of the orbits or their eventual destabilization. 7918:

is often used specifically to describe the orbit, gravity, and other properties of the Earth's Moon.

7850:

A dimensionless quantity that characterizes the radial distribution of mass inside a planet or moon.

3681:

A moment in time used as a reference point for some time-varying astronomical quantity, such as the

803:; and bodies similar to asteroids in size and composition but which lie beyond Jupiter are known as 547:. The term may also be used to refer to the value of the distance rather than the point itself. All 16854: 16824: 16702: 16468: 15123: 13549: 10847:

orbit, a satellite (red) orbits in the direction opposite the rotation of its primary (blue/black).

10574: 9622: 9422:, characterized generally by extremely low densities of particles, extremely low temperatures, and 7835: 5536: 5268:, which maintains a constant altitude of 35,786 kilometres (22,236 mi) directly above Earth's 4442: 2227: 388:. The spectrum of the Am stars shows abnormal enhancements and deficiencies of certain metals. See 379: 276: 15652:

Dynamics of the Milky Way: Tidal Streams and Extended Distribution Functions for the Galactic Disc

15149: 14559:

Astronomical Applications of Astrometry: Ten Years of Exploitation of the Hipparcos Satellite Data

9432:

is intergalactic space, and even galaxies and star systems consist almost entirely of empty space.

6989: 5430:, which can bend passing light from a distant source by a noticeable degree. The effect, known as 17009: 16984: 16819: 16814: 16563: 16349: 16208: 16187: 16146: 16110: 16078: 15538: 14269: 14134: 13727: 13428:

The transfer of momentum between an astronomical body and an orbiting satellite as the result of

12882: 12722: 12089: 11544: 11153: 10808:

Orbital or rotational motion of an object in the direction opposite the rotation of the object's

10471: 10214:

refers to a steady change in the orientation of an orbit, such as the precession in the orbit of

9877: 9810: 9661: 9598: 8736: 7884:, completing a full orbit every 27.3 days. The Moon's gravitational influence is responsible for 7650:. The name describes the galaxy's appearance from the Earth: a hazy band of light visible in the 7145: 6367: 5955: 4234:

lower (i.e. brighter) than 1.50. There are 22 stars that are classified as first magnitude stars.

4202: 4118: 4003: 2783:, at which it reaches its lowest point, nearly 12 hours later. When not otherwise qualified, the 2388: 1576:

were generated in the early Universe, including the means by which baryons outnumber antibaryons.

773:. Asteroids are somewhat arbitrarily distinguished from many different types of similar objects: 400: 256: 15097: 10283:

Orbital or rotational motion of an object in the same direction as the rotation of the object's

10122:

during the process of planet formation, but is also sometimes used to refer to various types of

8468:, and more specifically when clear weather and low levels of ambient light permit visibility of 1099:

A type of naturally occurring physical entity, association, or structure that exists within the

17039: 17024: 16616: 16489: 16482: 16405: 16199: 15598: 14249: 14156:. This linear relation makes it useful for determining the distances of G, K, and M-type stars. 14025: 13887: 13809: 13654: 13276: 12668: 12567: 12538: 11299:. It is expressed in units of length and often used to give a physical dimension to a two-body 11211: 11157: 10478: 10460: 10399: 10192: 8003: 6181: 5895: 5600: 5409: 5405:

in having a much higher combined mass, with a typical lifespan extending for billions of years.

5199: 4543: 4278: 3967: 3621: 2836: 2528: 2297:

A term used to indicate that two or more stars share the same motion through space, within the

2247: 2117: 2074: 1694:. At rotational velocities beyond this point, the star begins to eject matter from its surface. 1065: 899: 15730: 15619: 15465: 14763: 14726: 14451: 11886:

and all of the objects that orbit it, either directly or indirectly, including the eight true

4158:. An increase in faculae as a result of a stellar cycle increases the star's total irradiance. 2178:

above −4.2), active (−4.2 to −4.75), inactive (−4.75 to −5.1), and very inactive (below −5.1).

2064:, and generally also have unstable orbits because they cross the orbits of one or more of the 50:. The field of astronomy features an extensive vocabulary and a significant amount of jargon. 16894: 16586: 16280: 16218: 16041: 15867: 15565: 15410: 15284: 14557: 14514:"Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" 14420: 14366: 13359: 13280: 12486: 11511: 10955: 10707: 10071: 9683:

generally have low phase angles as seen from Earth, so they often appear as a slim crescent;

9510: 9390: 8567: 8432: 7342:

The measurement of positions of celestial objects based on observation of the times of their

7096: 6635: 4585:. It is approximately 8,200 parsecs (27,000 ly) away from Earth in the direction of the 4339: 3508: 3410:(grey) is defined by the Earth's orbit around the Sun, and is distinct from the plane of the 2489: 2314: 994:

The branch of astronomy that involves precise measurements of the positions and movements of

909: 557: 494: 15783: 15699: 15650: 15450: 15350: 15311: 15082: 14930: 14880:

Chebotarev, G. A. (April 1964), "Gravitational Spheres of the Major Planets, Moon and Sun",

14532: 14140:

A correlation between the width of the singly ionized calcium K-line (Ca II K) at 3933

13832:

width. It can be used to estimate the distance of the galaxy, and hence forms a rung on the

13446:

orbit will gradually recede from its primary while slowing the rotation rate of both bodies.

11019:

in which they formed, or otherwise have never been gravitationally bound to any star system.

10315:

The observed physical separation between two astronomical objects, as determined from their

5834:, and the plane containing Earth's rotational axis and the object of interest. Analogous to 1111:, consisting perhaps of multiple bodies or even other objects with substructures, such as a 17064: 17049: 17014: 17004: 16849: 16578: 16510: 16328: 16266: 16057: 16034: 16027: 15931: 15832: 15779: 15695: 15625: 15446: 15373: 15346: 15222: 15183: 15078: 15012: 14971: 14926: 14889: 14671: 14602: 14528: 14486: 14346: 13664: 13593:

in which the three bodies all differ greatly in mass. The parameter is calculated from the

13287:. These features need to be corrected for in order to more accurately measure the spectrum. 12319: 12107: 11112: 10621: 10611: 10411: 9818: 9524: 8976: 8881: 8871:

A gravitationally bound group of up to one thousand stars that formed together in the same

8546: 8073:

which travel together through space. Although the members were formed together in the same

7316: 6687: 5891: 5294: 4649:, usually home to a very dense concentration of stars and gas. It almost always includes a 4309: 4238: 4224: 3308: 2370: 1857:. Note that the Earth's rotational axis is not perpendicular to the ecliptic but rather is 1777: 1474: 1307: 717: 604: 15897: 13321:

slows to subsonic speeds (relative to the Sun) as a result of interactions with the local

6986:. The phase of the Moon at any particular time appears the same from every point on Earth. 6096:, both appear to travel with the Sun across the sky. This is in contrast to the so-called 2438: 332: 8: 17029: 16979: 16889: 16839: 16709: 16651: 16447: 16398: 16294: 16241: 16064: 15872:, Astronomy and Astrophysics Library, Springer Science & Business Media, p. 39, 14732: 14018: 13629: 12741: 12581: 12178: 11697: 11214:

caused by small-scale fluctuations in air density, and are much more pronounced near the

10383: 10235: 9752: 9042: 8766:, which is concerned with calculating the measurable implications of astronomical models. 8727: 6146: 6045: 5281: 5238: 5118: 5015: 4749: 4513: 4137: 3907:. An object which has achieved escape velocity is neither on the surface nor in a closed 2222:

A numeric value that is used to compare the brightness of a star measured from different

1868: 1633: 1356: 1139: 1084: 669: 336: 47: 43: 16762: 15836: 15377: 15226: 15187: 15016: 14975: 14893: 14675: 14606: 14583:

Townsend, R. H. D.; et al. (May 2004), "Be-star rotation: how close to critical?",

14490: 13275:

with nearly featureless continuum spectra that can be used to correct for the effect of

11481:, i.e. the time interval between two successive returns of the fixed stars to the local 6177:, but is enhanced by traces of other elements contributed by matter expelled from stars. 5437: 3754: 3608:

A relatively small body (such as a planet) orbiting a larger one (such as a star) in an

3448: 667:). The position of the ascending node with respect to a reference direction, called the 17090: 16738: 16637: 16342: 16312: 16259: 16194: 16142: 16117: 15848: 15822: 15795: 15769: 15711: 15685: 15391: 15199: 14989: 14961: 14916: 14689: 14620: 14592: 14323: 14048: 13957:

that describe them. When not otherwise qualified, "the Universe" usually refers to the

13589: 13413: 13331: 13209: 12513: 12400:

system. In the broadest sense, very large groups of stars bound by gravitation such as

12206: 11243: 11238:

Any change in movement that happens over a very long time period. Examples include the

10316: 10219: 9719: 9701: 8969: 8618:. It is often used as a diagnostic tool to determine the accuracy of the model. With a 8502: 8419: 8118: 7828: 7687: 6334:

positions of stars having the same age but differing masses. This is in contrast to an

6110: 5474: 5418: 5195: 4797: 4486: 4231: 3917: 3671:

at various dates and times. Modern ephemerides are often provided by computer software.

3628: 2182: 1918: 958: 478: 316: 194: 14684: 12895:

which possess masses ranging from hundreds of thousands to many billions of times the

12151: 10860: 3504:

to the ecliptic. It may be implemented in either spherical or rectangular coordinates.

3101: 2852: 1968: 1808: 1636:, a type of optical illusion which is entirely distinct from true binary star systems. 42:, their sub-disciplines, and related fields. Astronomy is concerned with the study of 16644: 16630: 16429: 16414: 16391: 16335: 16103: 15873: 15740: 15715: 15656: 15629: 15571: 15544: 15471: 15416: 15395: 15386: 15317: 15290: 15264: 15260: 15203: 15103: 15042: 14993: 14773: 14736: 14693: 14643: 14615: 14563: 14457: 14430: 14400: 14258: 14245:

that is directly overhead from the perspective of a particular location on the Earth.

14127: 13954: 13291: 13246:(i.e. in the tangent plane). This component can be computed from the body's observed 13002: 12770: 12630: 12271: 11596:, which results in the solar day being on average about four minutes longer than the 11320: 10802: 10696: 10415: 10206: 9954: 9228: 9070: 8282: 8233: 7854: 7777: 7140: 6683: 6597: 6351: 6324: 6316: 5905: 5900: 5887: 5758:. Satellites moving outside this radius tend to be perturbed away from the main body. 4438: 4329: 4268: 4174:

that does not belong to a larger cluster of galaxies and is gravitationally isolated.

4064: 4030: 3925: 3733: 3683: 3675: 3526: 3379: 2970: 2679: 2675: 1784: 1738: 1691: 1687: 1540:

of each body participating in the system; its location is strongly influenced by the

1393: 1210: 1010: 865:

to distinguish it from other asteroid populations in other parts of the Solar System.

507:

The closest approach of one celestial object to another, as viewed from a third body.

15852: 15799: 14624: 13349:

from its dark side. The line moves as the object rotates with respect to its parent

13215:

The straight-line configuration of three celestial bodies in a gravitational system.

12062: 10502:

as viewed from the Earth. The term is used especially to describe the position of a

10486: 9823: 7617:, in which the amplitude of the fluctuations amounts to just a few thousandths of a 7132:

which form a continuous and distinctive band on plots of stellar temperature versus

5578: 4812:. Galactocentric distance may also refer to a galaxy's distance from another galaxy. 4283: 3935:

of a particular mass and composition is expected to follow during the course of its

3842: 2412: 2240:

A relatively small, icy body that displays extended features when it approaches the

1818:, this plane is currently inclined at an angle of 23.44 degrees with respect to the 1726: 1025:

A type of naturally occurring physical entity, association, or structure within the

16549: 16528: 16363: 16356: 15840: 15787: 15703: 15381: 15191: 14979: 14934: 14679: 14610: 14536: 14494: 13871: 13825: 13777: 13686: 13472: 12704: 12679: 12590: 12434: 12305: 12267: 12228: 11776: 11140: 11023: 10782: 10688: 10464: 10215: 9991: 9924: 9735: 9365: 9203: 9181: 8998: 8851: 8615: 8170: 6556: 6257: 6235: 6203: 6070: 5971: 5819: 5769: 5561: 5434:, can make background objects appear to an observer to take on a ring or arc shape. 5369: 5182: 5125: 4624: 3723: 3558: 3350: 3346: 2497: 2461: 2146: 1976: 1531: 1454: 1378: 1331: 1265: 1228: 52: 15967: 15915: 15707: 14938: 14541: 11980:

were employed by astronomers as time reckoning systems before the introduction of

8754:

and other astronomical instruments. It is concerned with recording data about the

6385:. It is therefore widely used as the basis for defining the standard astronomical 5818:

that passes through the celestial object; or, equivalently, the angle between the

16695: 16370: 16287: 16225: 16180: 16124: 15791: 15217:

Sterken, C. (July 2005), Sterken, C. (ed.), "The O-C Diagram: Basic Procedures",

15052: 14193: 14188: 14028:

of velocities about the mean velocity for a group of objects, such as stars in a

12957: 12841: 12713: 12195: 11900: 11417: 11280: 11057: 10921: 10852: 10655: 10647: 10628: 10604: 10569: 10551: 10268: 10124: 9931: 8858: 8683: 8666: 8494: 8291: 8274: 7815: 7719: 7389: 7166: 6489: 6063: 5465: 5129: 5041: 5008: 5004: 4992: 4663: 4661:

in a compact region than its surroundings. This excess luminosity is known as an

4651: 4615: 4575: 4550: 4505: 4450: 3950: 3888: 3870:

each year. On the day of an equinox, the center of the visible Sun appears to be

3593: 3494: 3291: 3115: 3046: 3001: 2963: 2931: 2904: 2817: 2298: 2275: 2251: 2089: 2012: 1754: 1355:. The term often refers in particular to the gradual shift in the orientation of 841: 775: 300: 27:

List of definitions of terms and concepts commonly used in the study of astronomy

15415:, Cambridge Astrophysics, vol. 34, Cambridge University Press, p. 25, 15221:, vol. 335, San Francisco: Astronomical Society of the Pacific, p. 3, 14092: 13834: 13440:

for both bodies as well as modification of their mutual orbit. A satellite in a

12098: 11956:, i.e. the time interval between two successive returns of the Sun to the local 10791: 8640: 8492:. The night sky remains a fundamental setting for both amateur and professional 6771: 6692: 5136: 5070:

explosions of high-mass stars. Short GRBs may also result from the collision of

4774: 4558: 3816:

Either of the two precise times of year when the imaginary plane of the Earth's

3095: 2993: 1223:

or secondarily between the Earth and distant stars. Originally conceived as the

1202: 16542: 16475: 16377: 15099:

Astronomy for beginners : all you need to know to get started in astronomy

14984: 14330: 14273: 14117: 14041: 14040:. This value can be used to derive the combined mass of the group by using the 13950: 13851: 13702: 13399: 13125: 12815: 12792: 12675: 12346: 12169: 12130: 12005: 11666: 11232: 11170: 10991: 10107: 9900: 9855: 9697:

usually have high phase angles, so that little of the shadowed side is visible.

9654: 9131: 8762: 8719: 8626: 8557: 8162: 7827:

in which the prevailing physical conditions allow molecules to form, including

7579: 7549: 7370: 7149: 6757: 6661: 6601: 6266: 5685:

for temperature. Single stars of known mass and composition follow predictable

5657: 4975: 4892: 3904: 3896: 3836: 3486:, and a right-handed convention. This system is convenient because most of the 3405: 3133: 2878: 2810:

of dust and debris orbiting its host star. It is created by collisions between

2454: 1936: 1711: 1521: 1224: 634: 356: 228: 13105: 12907:, where they can have a profound effect upon the evolution of the surrounding 12762: 10927: 10758: 9582: 9248: 7527:. This makes many meteor showers predictable events, as they recur every year. 7451:, usually as a long streak of light produced when such an object is heated to 6627: 6302:. Irregular moons are thought to be captured from other orbits, as opposed to 6286: 5916:

A critical mass below which an astronomical object cannot sustain its surface

5286: 5264: 5029: 4356: 4301: 3661: 3581: 3317: 2682:. At this rotation rate, mass can be readily lost from the equator, forming a 2379: 2095: 2048: 1910: 1773: 1147: 979: 805: 462: 17079: 16600: 14141: 14087: 14011: 13991: 13963: 13829: 13736: 13644: 13613: 13459: 13323: 12976: 12787: 12736: 12448: 12219: 11964: 11837: 11723: 11693: 11660: 11627: 11491: 11451: 11270: 11132: 10752: 10712: 10670: 10651: 10642: 10590: 10363: 10339: 10178: 10112: 9934:

formed from a glowing shell of expanding plasma that has been ejected from a

9418: 9320: 9174: 9148: 9105: 8904: 8784: 8756: 8744: 8619: 8553:

A compact and dense concentration of stars located at the center of a galaxy.

8526: 8470: 8366: 8341: 8174: 8158: 8103: 8021: 7497: 7452: 7378: 7184: 7120: 7108: 7068: 7031: 6881: 6829: 6280: 6124: 6054: 5742: 5617: 5450: 5333: 5000: 4904:

bound together by gravity. Galaxy clusters are distinct from similarly named

4878: 4836: 4736: 4698: 4677: 4381: 4038: 3995:. Atmospheric extinction varies by the wavelength of the radiation, with the 3987: 3695: 3655: 3500: 3141: 2913: 2839:, and artist's impressions of the disks' orientations around their host stars 2717: 2420: 2396: 2154: 1996: 1886: 1594: 1446: 1312: 1290: 1251: 1101: 1057: 1027: 920: 813: 15056: 14146: 12607: 11196: 11063:

The time that an object takes to complete a single revolution about its own

10490:

that differ by 90 degrees as viewed from a third body, e.g. when a planet's

10063: 9302: 9214: 9123: 9099: 9062: 9033: 8520: 8347: 7823: 6905: 6847: 6483: 6359: 6336: 5687: 5669: 5477:

to collect observational data about astronomical objects and events such as

5444: 4922:. Galaxy groups and galaxy clusters can themselves cluster together to form 4503:, as opposed to everything outside of the Milky Way, which is the domain of 4022: 3957: 3398: 3367: 3024: 2886: 2806: 2757:. During each day, the Earth's rotation causes every astronomical object to 2684: 1165: 970:

where evidence for an unseen orbiting companion is revealed by its periodic

821: 779:

primarily composed of dust and ice instead of mineral and rock are known as

657: 208: 16556: 16535: 16153: 14860: 14211: 13863: 13782: 13745: 13707: 13541: 13483: 13305: 13236: 13175: 12970: 12943: 12832: 12756: 12748: 12660: 12364: 12125:. Instead, the evidence for the binarity comes from shifts observed in the 12028: 11918: 11868: 11859: 11810: 11680: 11371: 11337: 11009: 10962: 10898: 10870: 10842: 10740: 10732: 10716: 10327: 10302: 10138: 10094: 10039: 9977: 9800: 9490: 9423: 9310: 9192: 9079: 8922: 8865: 8833: 8778: 8575: 8538: 8402: 8345:

of indistinct nebulosity. In modern usage, the term typically refers to an

8313: 8250: 8052: 7968: 7943: 7880: 7863: 7785: 7769: 7737: 7307: 7235: 7226: 7201: 7022: 6581: 6519: 6417: 6330: 6292: 6274: 6238:

vector, and which may be regarded as the weighted average of all planetary

6077:. The name originated from the fact that these planets orbit closer to the 5862: 5851: 5802: 5693: 5341: 5303: 4983: 4932: 4860: 4411: 4354:

while traveling from north to south each year. It is directly opposite the

4350: 4317: 4299:

while traveling from south to north each year. It is directly opposite the

4295: 4162: 3937: 3866: 3824: 3782: 3776: 3738: 3550: 3476: 3418: 3385: 3270: 3241: 3206: 2987: 2862: 2691: 2480: 2338: 2321: 2103: 1904: 1840: 1791: 1769: 1706: 1673: 1566: 1388: 1345: 1274: 1107: 1002: 938: 929: 913: 904: 895: 869: 625: 305: 14312: 14294: 14030: 13794: 13772: 13672: 13595: 13139: 13059: 12986: 12903: 12473: 12414: 12201: 11876: 11528: 11443: 11391: 11301: 11248: 11228:

Continuing, or changing in a non-periodic way, over a long period of time.

11071: 11065: 11015: 10997: 10910: 10702: 10379:

as they collide with each other and gradually coalesce into larger bodies.

10200: 9983: 9837:

is used in reference to a planet-like object that is not orbiting the Sun.

9770: 9764: 9740: 9648: 9474: 9449: 9442: 9242: 9020: 8990: 8928: 8581: 8189: 7292: 7250: 7036: 6853: 6807:, and which therefore represents the distance of the orbit's longest axis. 6803: 6621: 6230: 5950: 5824: 5796: 5790: 5754: 5548: 5426: 5389: 5212: 5162: 4955: 4872: 4854: 4533: 4323: 4262: 4216: 4009:

The branch of astronomy that studies objects and phenomena outside of the

3854: 3770: 3728: 3689: 3611: 3412: 3361: 2765: 2520: 2428: 1956: 1950: 1833: 1796: 1546: 1536: 1351: 1113: 675: 616:

by humans, often around the Earth but also around other bodies within the

596: 549: 16798: 16623: 15827: 15774: 14859:, U.S. Naval Observatory and H.M. Nautical Almanac Office, archived from 14597: 14219: 14108: 14100: 14006: 13970:

2. One of many hypothetical parallel universes which exist as

13625:

With reference to, or pertaining to, a point on the surface of the Earth.

13450: 13442: 13436: 13065: 13042: 13034: 13028: 12873: 12809: 12616: 12373: 12135: 12081: 12074: 12060:

as seen from Earth; or, equivalently, when the Sun's apparent geocentric

11970: 11850: 11796: 11714: 11672: 11616: 11568: 11379: 11260:

With reference to, or pertaining to, the geometric center of the Earth's

10936: 10878: 10827: 10746: 10680: 10586: 10517: 10504: 10349: 10160: 9947: 9710: 9685: 9675: 9528: 9495: 9413: 9397: 9254: 9166: 9117: 8873: 8838: 8770: 8532: 8515: 8075: 7728: 7693: 7671: 7531: 7394: 7175: 7027: 6954:: as the orbital positions of the Moon around Earth and Earth around the 6927: 6811: 6466: 6098: 5960: 5844: 5836: 5725: 5609: 5570:, i.e. the arithmetic mean position of all points within the approximate 5529: 5525: 5512: 5327: 5315: 5276: 5128:

of the Earth, i.e. the arithmetic mean position of all points within the

4965:, and galaxy groups and clusters can themselves cluster together to form 4961: 4830: 4802: 4716: 4521: 4417: 4364: 3996: 3992: 3258: 3183: 3124: 2869: 2844: 2798: 2700: 2537: 2406: 2362: 2309: 2216: 2158: 2024: 1698: 1602: 1303: 1257: 891: 682: 326: 166: 14512:

Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009),

14300: 14152: 13857: 13601: 13393: 13157: 13099: 13081:). The synodic day may be described as the time between two consecutive 13022: 11982: 11934: 11702: 11459: 11425: 11210:

in the medium. Most terrestrial scintillation effects are the result of

10774: 10563: 10110:. The term is most commonly applied to small bodies thought to exist in 9872: 9758: 9344: 9270: 9111: 8044: 7773:

is not a minor planet because it orbits another body instead of the Sun.

7593: 7429: 7280: 7274: 7256: 6841: 6709: 5856: 5309: 5259: 4154: 3848: 3788: 3616:, with the larger body located at one of the focal points of the ellipse 3587: 3482: 3299: 3165: 3107: 3037: 2759: 2270: 2042: 1436: 1176: 584: 525: 342: 16593: 16570: 16050: 15470:, Oxford Quick Reference Online (3 ed.), Oxford University Press, 14769: 14215: 13820: 13637: 13467: 13370: 13248: 12858: 12478: 12266:

of an object in a vacuum near the surface of the Earth, as a result of

12068: 11990: 11976: 11926: 11732: 11362: 11348: 11207: 11107:

or other localized activity across the line of sight. Examples include

11048: 10675: 10578: 10419: 9087: 9056: 9027: 8804: 8796: 8790: 8137: 8079:, they have since moved too far apart to be gravitationally bound as a 7892: 7707: 7635: 7607: 7566: 7562: 7515:. These are produced by debris left over from a larger body, such as a 7212: 7153: 6962: 6861: 6769:), where the center part of the disk appears brighter than the edge or 6700: 6531: 6452: 6381: 6248: 6240: 6084: 5782: 5705: 5681: 5542: 5479: 5401: 5072: 4967: 4924: 4918: 4912: 4866: 4587: 4539: 4463: 4433: 4425: 4335: 4274: 4256: 3978: 3860: 3544: 3515: 3249: 3245: 3229: 3215: 3067: 2747: 2584: 2472: 2436:, while the modern demarcation of their borders was established by the 2401: 2303: 2255: 2162: 2150: 2030: 1847: 1720: 1715: 1648: 1640: 1514: 1470: 1430: 1407: 1320: 1295: 988: 966: 737: 279:

with characteristics indicating that the luminosity is not produced by

180: 174: 14036: 13788: 13607: 13477: 13093: 12795:

of hydrogen nuclei can be sustained (equivalent to approximately 0.08

12696: 12654: 12402: 12338: 12159: 11894: 11784: 11604: 11598: 11477: 11431: 11306: 11083: 10916: 10884:

A disk- or ring-shaped accumulation of various solid material such as

10616: 10434: 10375: 10176:

of the body being orbited during each revolution. It therefore has an

10172:

in which the orbiting object passes directly over or nearly over both

10152: 10146: 10057: 10033: 9906: 9894: 9829: 9642: 9472:

A unit of length defined as the distance at which a star would show a

9385: 9373: 9276: 9220: 9160: 8843: 8821: 8689: 8410: 8377: 8268: 8081: 7994: 7976: 7961: 7955: 7910: 7806: 7791: 7646: 7286: 7060: 7048: 6950: 6537: 6513: 6458: 6304: 6037: 5993: 5872:

but additionally taking into account the terrain and the depth to the

5635: 5321: 5110: 5088: 4906: 4722: 4492:

The branch of astronomy that studies objects and phenomena within the

4393: 4194: 4148: 4102: 4087: 4054:

or any objects larger than a star or the Solar System itself, such as

4044: 3701: 3575: 3454: 3373: 3079: 3073: 3030: 3018: 2981: 2943: 2925: 2892: 2890:

formed from gas ejected from a central star that now follows a nearly

2812: 2606: 2350: 2122: 2066: 1219: 1159: 1119: 972: 853: 827: 799: 759: 753: 663: 651: 618: 16688: 16015: 15011:, vol. 79, Dordrecht, D. Reidel Publishing Co., pp. 51–60, 14800:"Distance & Speed Of Sun's Orbit Around Galactic Centre Measured" 13971: 13713: 13475:

between an astronomical body and its gravitational partner. When the

13430: 13379: 13299: 13256: 13183: 13133: 13077: 12949: 12917: 12803: 12622: 12505: 12396: 12314: 12199:

which is used to locate the positions of astronomical objects on the

12119:

system where the individual components have not been resolved with a

12115: 11952: 11832: 11688: 11635: 11592: 11562: 11554: 11516: 11465: 11437: 11385: 11312: 11077: 10950: 10944: 10886: 10865: 10820: 10468: 10440: 10392: 10321: 10295: 10204:. For the Earth in particular, this phenomenon is referred to as the 10130: 10118: 10021: 9784: 9746: 9535: 9479: 9260: 8648: 8455: 8442: 8375:

that could not be resolved into their individual components, such as

8353: 8209: 7627: 7571: 7475: 7459: 7113: 7103: 7054: 6996: 6980:; when the illuminated portion is becoming smaller, it is said to be 6715: 6670: 6447: 5985: 5930: 5814: 5717: 5699: 5675: 5586: 5485: 5470: 5190: 5080: 5054: 5049: 5034: 4996: 4848: 4842: 4792: 4744: 4595: 4189: 4132: 3647: 3539: 3276: 3264: 3198: 2975: 2830: 2634: 2614: 2591: 2557: 2514: 2433: 2344: 2223: 2036: 1990: 1962: 1827: 1731: 1628: 1610: 1524:

about which any two or more bodies of a gravitationally bound system

1505: 1285: 1243: 1197: 886: 529:, one of the two extreme points of distance between the body and its 391: 384: 39: 35: 13976: 13814: 13697: 13569:

A measure of the orbital motion of a relatively small body (e.g. an

13535: 13471:

such that, over the course of an orbit, there is no net transfer of

13317: 13111: 12925: 12897: 12891: 12797: 12573: 12571:

scheme is a two-dimensional classification based on temperature and

12394:

that orbit each other, bound by gravitational attraction, such as a

12332: 12211: 11610: 11413:, which instead reckons time based on the Sun's position in the sky. 11335:

The precise time of year on Earth when the Sun appears to cross the

11097: 11035: 10557: 10524: 10492: 10260: 9940:

star late in its life. The name derives from their resemblance to a

9669: 9484: 9338: 8934: 8723:

when estimating the shape and characteristics of the object's orbit.

8657: 8587: 8371: 8325: 8129: 8109: 7664: 7613: 7483: 7447: 7268: 7199:

The precise time of year on Earth when the Sun appears to cross the

7134: 7076: 7042: 6743: 6393: 6224: 6189: 5924: 5918: 5748: 5651: 5623: 5491: 5449:, distorting the light from a much more distant blue galaxy into an 5361: 5355: 5230: 5224: 4657: 4581: 3943: 3846:

is either 0 degrees or 180 degrees. The two equinoxes, known as the

3736:. The plane of the Earth's terrestrial equator is the basis for the 3424: 3391: 3085: 2356: 2018: 1859: 1814: 1718:

in its core, with the latter being a characteristic of stars on the

1622: 1498: 1339: 415: 321: 271: 248: 220: 186: 15844: 15195: 14966: 14921: 14498: 13909: 13842: 13766: 13521: 13405: 13387: 13284: 13231: 13151: 13117: 12931: 12862: 12730: 12467: 12323: 12301: 12126: 12121: 12042: 12001: 11762: 11535: 11522: 11409: 11162: 11103: 10723: 10636: 10357: 10051: 9936: 9350: 8750: 8391: 8358: 8097: 7985: 7898: 7700: 7652: 7619: 7587: 7557: 7538: 7511: 7489: 7423: 7262: 6899: 6791: 6443: 6170: 6129: 6118: 6088: 6014: 5998: 5966: 5874: 5746:

within which its gravitational attraction dominates the motions of

5711: 5571: 5395: 5218: 5168: 5144: 5093: 5066: 5060: 5048:

A cataclysmic event that generates a brief but intense outburst of

5023: 4884: 4808: 4760: 4728: 4599: 4564: 4527: 4494: 4455: 4387: 4230:

A term used to classify the brightest stars in the night sky, with

4210: 4011: 3716:

The imaginary line on a gravitationally rounded spheroid such as a

3326: 3171: 2937: 2857: 2787:

typically refers to the time at which the upper culmination occurs.

1876: 1806:. On Earth, the plane of the celestial equator is the basis of the 1588: 1580: 1399: 1217:

A unit of length used primarily for measuring distances within the

1188: 1182: 793: 787: 745: 731: 590: 537: 439: 424: 15949: 15690: 13980:, which itself comprises all of space and time and their contents. 13770:

and the current position of an orbiting body as it moves along an

13678: 13571: 13242: 12690: 12561: 11958: 11906: 11586: 11483: 10835: 10045: 9613: 9559: 9428: 9389:

were absent, i.e. the orbit that coincides with the instantaneous

9208: 8994:, the eccentricity ranges from greater than zero to less than one. 8695: 8297: 8123: 7705:

is visible in dark skies on clear nights, in the direction of the

7441: 7392:

between 1771 and 1781. The Messier catalogue includes most of the

7360:

distance at those times, with the intention of obtaining accurate

7350: 7116:, although this can vary depending on sky conditions and eyesight. 6797: 6495: 6195: 6023: 5922:

through nuclear fusion. This mass limit, equal to about 7% of the

5868: 5808: 5497: 4949: 3879: 3722:

that represents the intersection of the spheroid's surface with a

3470: 2753: 2646: 2622: 2445: 2054: 1927: 1853: 1820: 1477:

above the horizon, it defines an object's current position in the

1434:. Axial tilt usually does not change considerably during a single 1383: 1361: 1261:, the origins of those objects and phenomena, and their evolution. 1171: 1051: 847: 594:, measured in the direction of motion. It is one of six canonical 543: 16794: 15337:

Hut, P. (June 1981), "Tidal evolution in close binary systems.",

13719: 13489: 13162: 13082: 13071: 13016: 12867: 12309: 11296: 11216: 11041: 10892: 10810: 10768: 10285: 10184: 10003: 9998: 9814: 9694: 9630: 9568: 9552: 9379: 9295: 9284: 9198: 8964: 8899: 8713: 8591:, which is a similar but longer-term change in axial orientation. 8465: 8415: 8369:. Historically, it was also used to refer to extended sources of 8201: 8038: 7922: 7798: 7344: 6593: 6507: 6439: 6298: 6093: 6032: 5762: 5270: 5101: 4988: 4669: 4192:

to a group of physically associated stars under study, such as a

3818: 3810: 3802: 3764: 3710: 3604: 3598: 3431: 3253: 3090: 2897: 2775: 2674:

The surface velocity at the equator of a rotating body where the

2286: 1802: 1463: 1424: 1299: 1281: 1193: 1153: 1061:

are often used interchangeably, there are technical distinctions.

1031:

that is a single, tightly bound, contiguous structure, such as a

836: 770: 531: 501: 469: 432: 372: 15869:

Stellar Interiors: Physical Principles, Structure, and Evolution

14182: 13937: 13925: 13583: 13515: 13345: 13195: 13189: 13145: 12909: 12849: 12442: 12420: 12408: 12312:

which, for at least a portion of its life, radiates energy into

12022: 12016: 11888: 11802: 11653: 11343: 11148: 10904: 10549:

A distant, point-like energy source originating from a powerful

10369: 10102: 10027: 9971: 9942: 9888: 9882: 9847: 9589: 9456: 9054:

around an astronomical body, expressed as the angle between the

8910: 8482: 8383: 8262: 8195: 7949: 7902:, though its orbital position with respect to the Earth and the 7757: 7640: 7505: 7467: 7356: 7330: 7207: 7082: 6982: 6976: 6875: 6749: 6737: 6501: 6165: 5944: 5854:

drawn upon the celestial sphere that passes through both of the

5830: 5774: 5520: 5349: 5174: 4900: 4780: 4754: 4704: 4645: 4569: 4499: 4471: 4170: 4081: 4056: 4016: 3872: 3718: 3639: 3534: 3488: 3153: 2955: 2949: 2735: 2508: 2083: 1898: 1558: 1131: 1125: 1039: 741:

or it may be composed of stars from more than one constellation.

697: 364: 311: 265: 214: 212:

the star would show if it were located at a distance of 10

16718: 14322:, and visible planets appear to travel across a band of twelve 14280: 14233: 14210:. They are usually produced when a high-mass object, usually a 13946: 13942: 13577: 13010: 12854: 12766:

that orbits another natural satellite, i.e. "a moon of a moon".

12471:, usually in the context of some region of interest within the 12426: 12327: 12034: 11997: 11912: 11824:

A standard unit of distance equal to the radius of the Earth's

10535: 10426: 10168: 10009: 9805: 9792: 9636: 9465: 9332: 9236: 9186: 9154: 9093: 9050: 9006: 8984: 8958: 8707: 8701: 8510: 8362: 8333: 8303: 8256: 8166: 7763: 7745: 7542: 7523: 7517: 7435: 7402: 7384: 7128: 6970:) and completely darkened by the Moon's own shadow (known as a 6835: 6785: 6587: 6434: 6387: 6174: 6154: 6069:

An archaic term that is sometimes used to refer to the planets

6028: 6018: 6010: 6006: 6002: 5532: 5383: 5377: 5105: 5097: 4898:

A large-scale structure consisting of hundreds or thousands of

4816: 4710: 4437:

that undergoes sudden, dramatic increases in brightness due to

3909: 3468:

defined by the plane of Earth's orbit around the Sun (i.e. the

2627: 2595: 2282: 2254:

around the cometary body. Sometimes a comet can produce a long

2060: 1881: 1656: 1573: 1572:

The process by which the class of subatomic particles known as

1544:

of each body and the distances between them. For example, in a

1526: 1441: 1105:

but is a more complex, less cohesively bound structure than an

781: 612: 578: 519: 448: 293: 236: 15435: 14318: 14264: 14122: 13999: 13931: 13509: 13495: 13351: 13339: 13271: 13161:, a result of the fact that both the body being studied (e.g. 13087: 12937: 12684: 12555: 12530: 12499: 12461: 12390: 11842: 11830:(typically measured from the Sun's center to the layer in the 11806:. Prominences may be hundreds of thousands of kilometers long. 11768: 11647: 11262: 11202: 11003: 10510: 10015: 9774:

are all commonly used as reference planes in various contexts.

9576: 9109:; in some contexts, the two nodes may be distinguished as the 8916: 8837:. It is thought to be divided into two regions: a disc-shaped 8634: 8622:, it is typically used to compare phase differences over time. 8573:

A continuous, gravity-induced change in the orientation of an

8488: 8476: 8069: 8001: 7886: 7658: 7362: 7272:

which a fictitious body would have if it moved in a perfectly

7088: 6944: 6919: 6869: 6827:

The angle between a specified reference direction, called the

6678: 6159: 5663: 4824: 4399: 4184: 4126: 4050: 3931: 3223: 3191: 3159: 2919: 2741: 2729: 1892: 1616: 1552: 1367: 1045: 1033: 996: 725: 703: 456: 281: 242: 202: 14316:

over the course of the year as observed from Earth. The Sun,

14306: 14288: 14241: 14207: 13916: 13691: 13311: 13201: 13167: 13057:

The time it takes for an object to rotate once about its own

12482: 12056: 12050: 12010: 11946: 11940: 11882: 11826: 11790: 11748: 11641: 11580: 11574: 11507: 11471: 11403: 11397: 10582: 10498: 9680: 9606: 9327: 9289: 9280: 8892: 8827: 8460: 8450: 8424: 8319: 8308: 8181: 7904: 7751: 7677: 7328:

and passing through the point directly overhead known as the

7324: 7158: 6956: 6890: 6765: 6542: 6525: 6079: 6074: 5629: 5592: 5566: 5149: 4786: 4446: 4405: 4397:

which do. The fixed stars are typically taken to include all

4344: 4342:, the First Point of Libra represents the point at which the 4289: 4142: 3830: 3758:

defined by an origin at the geometric center of the Earth, a

3706:

interval, with a given epoch as the temporal point of origin.

3667: 3633: 3460: 3355: 3235: 3147: 2723: 2600: 2502: 2466: 2242: 2234: 1984: 1944: 1373: 765: 709: 511: 408: 15984: 15597:, Center for Computational Physics in Hawaii, archived from 11782:

A large, bright, transient feature, often in the shape of a

10484:

A configuration in which two celestial bodies have apparent

7366:

positions which are self-consistent over large areas of sky.

6966:

Earth alternates between completely illuminated (known as a

4441:

on its surface. This change in brightness occurs across the

3591:, which have eccentricity equal to 0), or one with negative 1948:

at which a hypothetical indefinite extension of the Earth's

1145:

Any abstract pictorial symbol used to represent one or more

15102:(Third ed.), Imagine Publishing Limited, p. 151, 14906: 14476: 13920: 13181:

The calculation of the passage of time based on successive

12294: 9690: 9482:

as observed from Earth's orbit. It is equal to 3.2616

9274:

are related by a ratio of small integers. For example, the

9127:, which is coplanar with the reference plane, has no nodes. 7872: 7487:. If it survives to reach the surface, it is then termed a 6894: 6818: 6103: 6027:

with freezing points above 100 K (−173 °C), e.g.

2769:, creating two points at which it crosses the meridian: an 2552: 2165: 1541: 832: 497:. The brighter the object appears, the lower its magnitude. 348: 34:

is a list of definitions of terms and concepts relevant to

12791:

whose mass is smaller than the smallest mass at which the

12566: 12054:

reaches its most northerly or most southerly point in the

11383:

of an object (e.g. the Earth) with respect to the distant

9574:

The point at which a body orbiting the Earth (such as the

8962:. For a binary system, it is typically presented from the 2773:, at which the object reaches its highest point above the 1690:

generated by a rapidly spinning star matches the force of

912:, and how humans might be able to detect extraterrestrial 454:

The point at which a body orbiting the Earth (such as the

16792: 16160: 15902:

A Knowledgebase for Extragalactic Astronomy and Cosmology

12823: 11746:

A standard unit of mass equal to the mass of the Earth's

11500: 11487:, as viewed from a given location on the Earth's surface. 9013: 7080:, interacts with the magnetic field of a body, such as a 7074:

A mostly convex region formed when a plasma, such as the

6134: 5188:

The ratio of the brightness of an astronomical body at a

3947:

that a star will have during part or all of its lifetime.

3941:. This curve predicts the combination of temperature and 1491: 430:

The point at which an orbiting body is furthest from its

14900: 14292:

that extends approximately 8 degrees north or south (in

12853:

that orbit further from the Sun than the Earth, such as

12274:

generated by its rotation. It is by definition equal to

11295:

One half of the longest diameter (the major axis) of an

7878:

The solid, rocky body that orbits the Earth as its only

6374:

A unit of time defined as exactly 365.25 days of 86,400

5381:

which are gravitationally bound to each other and which

4475:

having a size between 1.5 and 2 times that of the Earth.

3840:); or, equivalently, when the Sun's apparent geocentric 3834:(i.e. the two points at which this plane intersects the 2285:

around the Sun is very nearly 5/2 the orbital period of

2081:

Any very large concentration of mass at the center of a

1982:

An imaginary sphere that encompasses the Earth's entire

1760:

A star used for calibration of high-powered teleescopes.

15176:

Publications of the Astronomical Society of the Pacific

12664:

over time based upon its mass and chemical composition.

12139:

of the components change over the course of each orbit.

11700:. The Sun's faculae are most readily observed near the 10694:

A conspicuous trail of enlarged red stars found on the

10589:

and optical spectra are characterized by strong, broad

7284:

as the actual body in its elliptical orbit. Unlike the

6619:. The phenomenon is the basis for the stable orbits of 5375:

A tight, spherical conglomeration of many thousands of

3601:, and are very common in two-body astronomical systems. 3458:, with an origin at the geometric center of either the 2268:

A property of two objects orbiting the same body whose

1151:, events, or theoretical constructs, e.g. those of the 190:, and have surface temperatures of 7,600–10,000 kelvin. 15244:, New York: McGraw-Hill Book Company, pp. 70–124. 14511: 14116:. A white dwarf lacks the mass needed to continue the 12412:

are also star systems. Star systems are distinct from

11526:, the term "sky" is also used as another name for the 10942:

The distance from an astronomical object at which the

9550:

The point at which an orbiting body is closest to its

7908:

causes its visibility to change in a regular cycle of

7011: 6867:

The total amount of energy emitted per unit time by a

5469:

which analyzes minute distortions in the curvature of

4667:, and the brightest such active galaxies are known as 2896:

around it. This type of disk can be found around many

785:; bodies less than one meter in diameter are known as 14661: 14582: 13075:

it is orbiting (rather than to the much more distant

11766:. It is commonly used to express the masses of other 11156:

of a more massive and luminous host galaxy; e.g. the

11136:

was first noted by American astronomer Stephen Saber.

10459:

A method of computing the mean strength of a varying

9416:

expanse that exists beyond the Earth and between all

8681:

The duration of time between the earliest and latest

7481:

A small rock or boulder that has entered a planetary

4720:. Estimates of the duration of one revolution of the 4531:, as viewed from Earth; considered as a point on the 4519:

The direction in space that is directly opposite the

2437: 1556:

is significantly larger than the mass of an orbiting

15759: 15363: 14090:

for a star compared to standard stars with the same

13581:) with respect to a larger, perturbing body (e.g. a 13487:

orbits with the same face always pointed toward its

12611:; or another name for the stellar atmosphere itself. 12485:

could be defined as encompassing some or all of the

11932:

The calculation of the passage of time based on the

11457:

The calculation of the passage of time based on the

10025:. In general, planetary systems include one or more 9751: 9640:

characteristics of the body such that the idealized

6960:

change, the visibility of the side of the Moon that

3022:

at which an orbiting object moves south through the

2563: 668: 655:

at which an orbiting object moves north through the

15675: 15402: 15041:(2nd ed.), New York: Oxford University Press, 13193:(i.e. successive returns of the object to the same 12847:An archaic term that is sometimes used to refer to 12477:. For example, the starfield surrounding the stars 12465:visible in an arbitrarily sized field of view of a 6686:. It can allow normally hidden parts of the Moon's 5596:; centered upon the Sun, e.g. a heliocentric orbit. 5178:

as defined with respect to the center of the Earth.

5152:; centered upon the Earth, e.g. a geocentric orbit. 3753: 3447: 1831:A diagram of the relationships between the Earth's 1280:The branch of astronomy that employs principles of 535:– either the point of minimal distance, called the 14718: 14422:Physics, Formation and Evolution of Rotating Stars 13588: 13240:that is perpendicular to the line of sight of the 11788:, consisting of plasma extending outward from the 10954:. Outside this limit, loose material will tend to 10198:Any slow change in the orientation of an object's 10182:equal or nearly equal to 90 degrees to the body's 9287:, such that Pluto completes two orbits around the 9060:or axis of direction of the orbiting object and a 7537:A measure of the abundance of elements other than 6735:). Though the light-year is often used to measure 6600:of orbital motion, and (in certain scenarios) the 5633:. The heliosphere encompasses the entirety of the 4287:of (0°, 0°) and represents the point at which the 3514:(of a star or planet) The temperature of an ideal 610:An object that has been intentionally placed into 329:and geological or environmental surface features). 15366:Monthly Notices of the Royal Astronomical Society 15303: 14585:Monthly Notices of the Royal Astronomical Society 14453:Astronomical Observations, An Optical Perspective 14268:which have finished contracting and have reached 14262:achieved by newly formed, chemically homogeneous 12880: 12048:Either of the two precise times of year when the 11542: 11075:. It is not necessarily the same as the object's 10859: 9164:, the orbital period is often referred to as the 8036:The horizontal angular distance between the rise 7509:that seemingly radiate from a single area in the 5058:away. The source of most GRBs is theorized to be 5052:radiation which can be detected from billions of 4916:and from smaller aggregates of galaxies known as 3256:. Confusingly, the term has also come to include 3100: 2851: 1967: 1807: 17077: 15570:, Universitätsverlag Göttingen, pp. 54–59, 15068: 14945: 14257: 14247: 14046: 13337:The line that divides the illuminated side of a 11013:. Such objects have often been ejected from the 10814:. The direction of rotation is determined by an 10695: 10289:. The direction of rotation is determined by an 10205: 9377:that an orbiting object would follow around its 7260:that has elapsed since the orbiting body passed 7139: 6323: 6106:, which appear to move independently of the Sun. 5899: 5772:perpendicular to a line from an observer to the 5194:of zero to an idealized flat, fully reflecting, 4947:A gravitationally bound aggregation of up to 50 4732:range from 225 to 250 million terrestrial years. 4328: 4267: 3924: 3682: 3378: 1392: 839:that is occupied by numerous irregularly shaped 254: 13652: 12061: 11475:. The fundamental unit of sidereal time is the 11347:passage. It represents the moment at which the 10485: 9822: 9604:The point at which a body orbiting the Earth's 7211:passage. It represents the moment at which the 6763:An optical effect seen in stars (including the 5455: 5424:Any very large distribution of mass, such as a 4655:which, when active, can generate a much higher 4282: 3841: 3744: 3297:A hotter and more massive star, in contrast to 2929:. The classification is used mostly in amateur 2411: 2110: 2072: 2052:that typically exhibit characteristics of both 1725: 541:, or the point of maximal distance, called the 406:The point at which a body orbiting the Earth's 234:A roughly circular mass of diffuse material in 54: 15728: 15493:HubbleSOURCE: Constellation Mythological Forms 15408: 14873: 14724: 14470: 12740:detectable at submillimetre wavelengths (i.e. 11506:Everything that lies above the surface of the 10404: 10224: 10069: 9004:The set of parameters that uniquely define an 8819:A vast theoretical cloud of predominantly icy 8430: 8101:based on the acquisition of information about 7298: 5641: 3762:created by projecting the Earth's terrestrial 2997:, such that normal atoms cannot exist in them. 2620:Any model concerning the origin of either the 2487: 1724:. Brown dwarfs can still generate energy from 1626:. The term is often used interchangeably with 1337:A slow, continuous, gravity-induced change (a 16778: 16000: 15865: 15309: 14637: 14399:, Cambridge, UK: Cambridge University Press, 14396:Cambridge Illustrated Dictionary of Astronomy 14326:within this belt as the Earth orbits the Sun. 12935:stellar explosion occurring during a massive 11846:and astronomical objects relative to the Sun. 11772:and astronomical objects relative to the Sun. 11341:, while generally trending southward at each 9788:of an orbital plane of a distant star system. 8776:A celestial event that occurs when a distant 8742:The practice and study of directly observing 8544: 8173:that are radio sources and display prominent 7266:, expressed as the angular distance from the 7205:, while generally trending northward at each 6903:. Luminosity is related to but distinct from 6406: 5778:that passes through the point of observation. 5331:equal to 35,786 kilometres (22,236 mi); 5292: 4604: 3985:by matter (dust and gas) between an emitting 3653:A list or table of the expected positions of 3438: 2500:and the accompanying magnetic field from the 2205: 2198: 1800:that is coplanar with the body's terrestrial 206:'s absolute brightness. It is defined as the 15968:"Glossary of (comet and) astronomical terms" 15866:Hansen, Carl J.; Kawaler, Steven D. (1999), 15567:3D-Spectroscopy of Dense Stellar Populations 15530: 15357: 15210: 15071:Astronomy and Astrophysics Supplement Series 14655: 14192:, yet displays an anomalous level of excess 14187: 13547: 13252:and its measured distance from the observer. 13091:), which is not necessarily the same as the 12968:experienced at the equatorial surface of an 12194: 11950:. The fundamental unit of solar time is the 11899: 11692:of the Sun that form in the canyons between 10678:into space. These objects are the basis for 10568: 10550: 10123: 9912: 9017:A diagram showing four of the six canonical 8800:eclipses are specific types of occultations. 8717:), and therefore result in a high degree of 8687:made by astronomers of an object within the 8682: 8493: 8307:, whose orbit brings it into proximity with 8290: 8273: 8087: 7398:easily visible from the Northern Hemisphere. 7144:. These stars are characterized by being in 7026:that might explain the apparent presence of 6488: 6244:and rotational planes comprising the system. 6144: 5464: 5337:are a special case of geosynchronous orbits. 4662: 4650: 4574: 4504: 4236: 3592: 3493: 2930: 2575:cosmic microwave background radiation (CMBR) 2313:parameters, which may suggest that they are 2301:. That is, either they have nearly the same 2088: 2011: 1294:and phenomena, examining properties such as 840: 791:; very large asteroids are sometimes called 774: 15956:, Space Telescope Science Institute (STScI) 15812: 15729:Jaschek, Carlos; Jaschek, Mercedes (1990), 15722: 15669: 15642: 15611: 15457: 15276: 15062: 15000: 14755: 14576: 14549: 14505: 14456:, Cambridge University Press, p. 109, 14091: 13974:disconnected constituent parts of a larger 13833: 12097: 11395:(rather than to its primary star, e.g. the 10453: 9234:The situation that occurs when two or more 8831:at distances ranging from 2,000 to 200,000 8639: 8004:Morgan–Keenan stellar classification system 7914:when viewed from the Earth. The adjectival 7833: 7569:. Micrometeorites are a major component of 5691:across this chart over the course of their 5673:may be substituted for luminosity, and its 5166:by a straight line that passes through the 4773: 4557: 3094: 2992: 1201: 1055:. Though the terms astronomical "body" and 769:at a distance no greater than the orbit of 735:. An asterism may form part of an official 16785: 16771: 16007: 15993: 15859: 15557: 15429: 15289:, Cambridge University Press, p. 87, 15233: 15167: 15030: 15028: 15026: 14951: 14879: 14728:Evolution of stars and stellar populations 14725:Salaris, Maurizio; Cassisi, Santi (2005), 14562:, Cambridge University Press, p. 80, 13850: 13670:1. The passage of a particular 13398: 12814: 12720: 12637: 12087: 11665: 11021: 10990: 10864:, the celestial equivalent of terrestrial 10373:; they are thought to form out of smaller 10031:, though such systems may also consist of 9899: 9876:that is geologically differentiated or in 9634:alone, or any force which complicates the 9158:around another object. For objects in the 8761: 8734: 8718: 8280: 7681:orbits with a period of 240 million years. 6719:: approximately 9.46 trillion kilometres ( 5656: 4766: 4001: 3999:being greater for blue light than for red. 3835: 3404: 3196:which they may form a co-moving pair or a 2985:. These stars are in an advanced state of 2856:, the celestial equivalent of terrestrial 2368: 2250:on a comet's surface, producing a visible 1495:Two bodies of similar mass orbit a common 15826: 15773: 15689: 15537:Andersen, J. (2000), Livio, Mario (ed.), 15385: 15316:, Cambridge University Press, p. 4, 15115: 14983: 14965: 14920: 14683: 14640:The Facts on File Dictionary of Astronomy 14614: 14596: 14540: 14443: 13885: 13599:of each body, including the small body's 13499:, which is tidally locked with the Earth. 13104: 12953:is triggered into runaway nuclear fusion. 12761: 12666: 12536: 11996:A stream of charged particles, primarily 11696:. They are produced by concentrations of 10926: 10757: 10496:is perpendicular to the direction of the 9581: 9247: 7521:, and hence they follow roughly the same 6626: 6285: 6179: 5997:composed mainly of elements heavier than 5910: 5584:With reference to, or pertaining to, the 5407: 5285: 5263: 5142:With reference to, or pertaining to, the 5100:gases rather than heavier elements, e.g. 5028: 4822:A large, gravitationally bound system of 4355: 4300: 3699:, because such quantities are subject to 3660: 3597:. Elliptical orbits take the shape of an 3580: 3518:that would emit the same total amount of 3316: 2816:. A debris disk can be discerned from an 2526: 2378: 2094: 2047: 1909: 1632:, though the latter can also refer to an 1440:; Earth's axial tilt is the cause of the 1208: 1146: 1063: 978: 804: 461: 299:A measure of the proportion of the total 46:and phenomena that originate outside the 15806: 15753: 15655:, Springer Theses, Springer, p. 9, 15536: 15141: 15095: 14847: 14845: 14843: 14841: 14839: 14555: 14412: 14388: 14386: 14384: 14382: 14272:, with energy being derived solely from 13962: 13800: 13643: 13636: 13612: 13368: 13357: 13322: 13115:; Earth's synodic day is often called a 12975: 12786: 12735: 12150: 11963: 11659: 11131: 11089: 10908:. Ring systems are common components of 10834: 10751: 10669: 10641: 10516: 10362: 10319:and estimated distance. For planets and 10177: 10111: 9904:, but excluding smaller objects such as 9508: 9441: 9417: 9330:at which an astronomical body or object 9301: 9147: 9104: 9012: 8982:A parameter that determines how much an 8903: 8783: 8755: 8743: 8525: 8469: 8340: 8102: 7686: 7611:that undergoes very small variations in 7377: 7107: 6988: 6880: 6828: 6682:as seen from the Earth, a result of the 6633: 6279: 6222:The imaginary plane passing through the 6123: 6053: 5741: 5616: 5441:A luminous red galaxy (LRG) acting as a 5436: 5332: 5039: 4877: 4835: 4697: 4602:, where the Milky Way appears brightest. 4380: 4037: 3986: 3949: 3694: 3654: 3603: 3506: 3499: 3397: 3140: 2912: 2902: 2822: 2716: 2464:that surrounds cooler stars such as the 2395: 1995: 1885: 1826: 1593: 1490: 1445: 1311: 1289: 1250: 1100: 1056: 1026: 857:. The asteroid belt is often called the 555: 331: 15648: 15463: 15254: 15216: 15089: 15034: 15023: 15006: 14837: 14835: 14833: 14831: 14829: 14827: 14825: 14823: 14821: 14819: 14761: 14638:Daintith, John; Gould, William (2009), 14145: 13967:, whose size it is possible to measure. 13377: 12606: 12105: 11195: 10309: 10062: 9809:the Sun, which is massive enough to be 9218:for the orbits of other objects in the 9213: 9122: 9098: 9061: 9032: 8988:deviates from a perfect circle. For an 8974: 8519: 8346: 7822: 6904: 6846: 6535:but far larger, and is home to several 6482: 6358: 6335: 5904:, these stars are positioned where the 5686: 5668: 5443: 5132:that is the precise shape of the Earth. 4537:, the Milky Way's anticenter is in the 4307: 4281:, the First Point of Aries defines the 4222: 4048:. The term is generally not applied to 4021: 3956: 3825:extended indefinitely in all directions 3366: 3023: 2885: 2805: 2683: 2291: 1710:that is too low in mass to sustain the 1164: 845:ranging in size from dust particles to 820: 656: 602: 466:) is furthest from the Earth. Contrast 382:belonging to the more general class of 285:. A galaxy hosting an AGN is called an 207: 14: 17078: 16900:Electrical and electronics engineering 16885:Developmental and reproductive biology 15617: 15563: 15540:Unsolved Problems in Stellar Evolution 15282: 15239: 15173: 14449: 14425:, Astronomy and Astrophysics Library, 14418: 14392: 14132: 14016: 13862: 13781: 13706: 13627: 13540: 13482: 13304: 13235: 13224: 12984:(m/s) or as a multiple of the Earth's 12969: 12955: 12942: 12755: 12678:generated by the convective motion of 12659: 12579: 12176: 12027: 11917: 11858: 11686:Solar faculae are bright spots in the 11336: 11101:of a star to vary as rotation carries 11008: 10897: 10869: 10841: 10739: 10474:measurements taken at different times. 10463:. It is determined by calculating the 10381: 10326: 10301: 10038: 9976: 9799: 9489: 9356: 9309: 9283:exists in a stable 2:3 resonance with 9191: 9040: 8921: 8832: 8777: 8725: 8574: 8537: 8312: 8249: 7967: 7942: 7879: 7862: 7784: 7768: 7382:, 103 of which were catalogued as non- 7322:A line running north–south across the 7306: 7225: 7200: 7106:scale indicating the brightness of an 7021: 6783:The imaginary line connecting the two 6580: 6579:Any of a set of points near two large 6518: 6329: 6291: 6273: 5974:systems are examples of hypergalaxies. 5861: 5860:and is therefore perpendicular to the 5801: 5692: 5621:which surrounds and is created by the 5302: 5236: 5013: 4982: 4859: 4772:A star or cluster's distance from the 4748:experienced by objects subject to the 4511: 4410: 4349: 4316: 4294: 3936: 3865: 3823: 3781: 3775: 3737: 3549: 3475: 3417: 3384: 3269: 3240: 2986: 2861: 2690: 2337: 1988:and is stationary with respect to the 1942:One of two coordinates in the Earth's 1903: 1866: 1839: 1705: 1672: 1344: 1137: 1106: 1082: 1001: 928: 903: 831:located roughly between the orbits of 624: 304: 16766: 15988: 15621:Formation and Evolution of Exoplanets 15007:Einasto, J. (1978), "Hypergalaxies", 14427:Springer Science & Business Media 14379: 14311: 14293: 14029: 13793: 13771: 13671: 13594: 13187:of an astronomical object, such as a 13138: 13058: 12985: 12902: 12568:Morgan–Keenan spectral classification 12511: 12472: 12413: 12200: 11875: 11527: 11442: 11390: 11359:in the Southern Hemisphere. Contrast 11300: 11247: 11070: 11064: 11014: 10996: 10909: 10701: 10514:at its first and last quarter phases. 10199: 9982: 9769: 9763: 9739: 9717: 9699: 9647: 9473: 9460:as seen from the Earth (not to scale) 9454:shift of a star at a distance of one 9448: 9241: 9019: 8989: 8927: 8580: 8500: 8188: 7336: 7291: 7249: 7223:in the Southern Hemisphere. Contrast 7035: 6852: 6802: 6620: 6229: 6157:that exists in the space between the 6108: 5949: 5823: 5795: 5789: 5753: 5667:; depending on the usage, the star's 5547: 5425: 5416: 5388: 5211: 5204: 5172:and an observer; i.e. the observer's 5161: 4954: 4871: 4853: 4532: 4484: 4322: 4261: 4215: 4208:The first use of a newly constructed 4152:) are most readily observed near the 3915: 3853: 3769: 3727: 3688: 3610: 3411: 3371:for describing the position of other 3360: 2764: 2519: 2427: 2281:. For example, the orbital period of 2180: 1955: 1949: 1916: 1832: 1795: 1762: 1545: 1535: 1350: 1112: 956: 674: 595: 548: 476: 269:displaying a much higher than normal 192: 16746: 15583: 15507: 15409:Schrijver, C. J.; Zwaan, C. (2008), 15310:MacEvoy, Bruce; Tirion, Wil (2015), 15147: 14816: 14792: 14664:The Astrophysical Journal Supplement 14256:The sequence of positions along the 14174:X-ray bright optically normal galaxy 14107: 14086:A reference to the faintness of the 14005: 13441: 13435: 13289: 13085:(in the case where the primary is a 13064: 13033: 13027: 13000: 12872: 12808: 12768: 12688:, responsible for phenomena such as 12628: 12615: 12256:standard acceleration due to gravity 12134: 12080: 12073: 11969: 11795: 11706:. Faculae occur on other stars (see 11671: 11615: 11567: 11378: 11318: 11124: 10826: 10800: 10762:. Regular moons are thought to form 10745: 10679: 10573:. Quasars emit radiation across the 10503: 10325:, this distance is usually given in 10218:that was explained by the theory of 9952: 9684: 9674: 9586:) is closest to the Earth. Contrast 9253: 9226: 9165: 9116: 9068: 8872: 8531: 8414:that is composed almost entirely of 8231: 8074: 7775: 7727: 7692: 7670: 7393: 7174: 6349: 6097: 5959: 5835: 5615:The vast, bubble-like cavity in the 5326: 5314: 5275: 5154: 4960: 4959:. Larger aggregations may be called 4829: 4801: 4715: 4520: 4416: 4062: 4028: 3800:Of, relating to, or occurring at an 3524: 3304:rather than of all stars in general. 3257: 3227:belonging to a category of ordinary 3123: 3086:point of closest approach to the Sun 2935:to distinguish faint objects in the 2868: 2751:, etc.) across the observer's local 2659: 2652: 2642:origin, evolution, and eventual fate 2405: 2361: 2308: 2246:. The energy from the Sun vaporizes 2023: 1782: 1663: 1256: 1008: 681: 263:A compact region in the center of a 15484: 15412:Solar and Stellar Magnetic Activity 15336: 15257:Introduction to Celestial Mechanics 15150:"Al Khwarizmi: A Medieval Polymath" 15148:Umar, Khalid Bin (18 August 2019), 14299: 14151: 13869: 13856: 13764:The angle between the direction of 13600: 13392: 13156: 13098: 13021: 12702: 12597: 12588: 12432: 12226: 11981: 11933: 11774: 11701: 11608:and because its rotational axis is 11458: 11424: 11355:in the Northern Hemisphere and the 11138: 11045:to radiation at a given depth. See 10780: 10778:, which are thought to be captured. 10773: 10686: 10562: 9989: 9922: 9871: 9817:(but not massive enough to achieve 9776: 9757: 9363: 9343: 9269: 9110: 8996: 8311:, generally by being less than 1.3 8043: 7592: 7428: 7279: 7273: 7255: 7219:in the Northern Hemisphere and the 6840: 6708: 6676:A slight oscillating motion of the 6554: 6255: 6201: 5855: 5697:. Hence, knowing a star's mass and 5367: 5325:. All geosynchronous orbits have a 5308: 5258: 5180: 4953:, each at least as luminous as the 4622: 4153: 3847: 3828:, passes through the center of the 3787: 3586: 3585:of less than 1 (often inclusive of 3556: 3481: 3365:. The ecliptic is widely used as a 3298: 3164: 3106: 3036: 2758: 2269: 2260: 2041: 1974: 1452: 1435: 1391:, and is the cause of the apparent 1329: 1263: 1175: 976:of the visible component. See also 583: 524: 412:is furthest from the Sun. Contrast 341: 240:around a central object, such as a 151: 24: 14631: 13819: 13466: 13247: 12839: 12711: 12067: 11975: 11415: 11361: 11278: 11055: 11047: 10874:into 24 hours, each of 60 minutes. 10850: 10626: 10602: 10521:A moon or planet is said to be in 10266: 9086: 9055: 9026: 8956:A schematic diagram of a complete 8795: 8789: 8664: 7891: 7844:normalized polar moment of inertia 7813: 7706: 7634: 7606: 6961: 6777: 6698: 6530: 6451: 6380: 6365: 6239: 6061: 5928:, forms the dividing line between 5880: 5704: 5680: 5541: 5478: 5400: 5216:or otherwise) with respect to the 5071: 4966: 4923: 4917: 4911: 4865: 4675: 4613: 4586: 4548: 4538: 4432: 4334: 4273: 4255: 4020:, i.e. all objects not covered by 3886: 3859: 3543: 3289: 3228: 3066: 3044: 2999: 2961: 2746: 2471: 2302: 2126:. One measure of this activity is 2029: 1846: 1752: 1719: 1686:The surface velocity at which the 1647: 1429: 965: 736: 179: 173: 25: 17107: 16930:Genetics and evolutionary biology 15890: 15286:Astronomy: A Physical Perspective 15121: 14328: 14080: 14035: 13787: 13606: 13476: 13123: 13092: 12901:. These are typically found at a 12695: 12653: 12401: 12344: 12337: 12167: 12158: 11893: 11783: 11603: 11597: 11572:of the Earth with respect to the 11476: 11430: 11305: 11230: 11194:Rapid variations in the apparent 11168: 11082: 10915: 10744:following a relatively close and 10615: 10433: 10374: 10151: 10145: 10056: 10032: 9905: 9893: 9853: 9828: 9738:from which to measure and define 9734:An arbitrarily chosen, imaginary 9641: 9517: 9384: 9372: 9275: 9219: 9159: 9129: 8842: 8820: 8688: 8624: 8555: 8409: 8376: 8267: 8080: 7993: 7975: 7960: 7954: 7909: 7805: 7790: 7645: 7577: 7547: 7421:The visible passage of a glowing 7368: 7285: 7059: 7047: 6949: 6897:, and is often given in terms of 6889:units, luminosity is measured in 6755: 6659: 6536: 6512: 6457: 6303: 6264: 6169:. This medium mainly consists of 6083:than the Earth and hence, in the 6036: 5992: 5908:of both variable classes overlap. 5740:The approximate region around an 5634: 5320: 5109: 5087: 4973: 4905: 4890: 4721: 4392: 4193: 4147: 4101: 4086: 4043: 3700: 3574: 3453: 3372: 3131: 3078: 3072: 3029: 3017: 2980: 2942: 2924: 2891: 2876: 2811: 2605: 2349: 2121: 2065: 1934: 1218: 1158: 1118: 971: 852: 826: 798: 758: 752: 662: 650: 632: 617: 354: 226: 16745: 16734: 16733: 16504:Southern African Large Telescope 15387:10.1111/j.1365-2966.2008.14227.x 14616:10.1111/j.1365-2966.2004.07627.x 14362:List of common astronomy symbols 14186:that does not appear to have an 13989: 13792:, and also one of six canonical 13734: 13712: 13457: 13434:. This can cause changes in the 13429: 13411: 13298: 13263: 13182: 13132: 13076: 12948: 12802: 12621: 12504: 12395: 12313: 12217: 12114: 11951: 11831: 11721: 11687: 11634: 11625: 11591: 11561: 11515: 11489: 11464: 11449: 11436: 11384: 11311: 11268: 11254: 11240:perihelion precession of Mercury 11177: 11076: 10949: 10943: 10885: 10819: 10439: 10361:embryo that originated within a 10337: 10320: 10294: 10129: 10117: 10020: 9783: 9745: 9610:is closest to the Sun. Contrast 9318: 9306:A planetary system showing a 1:2 9259: 9172: 8352: 8019: 7599: 7570: 7495: 7182: 7118: 7066: 7053: 6995: 6942:The shape of the portion of the 6714: 6450:, which forms a two-dimensional 6438:body relative to another, as an 6137:International Astronomical Union 5948:accompanied by multiple smaller 5929: 5813: 5716: 5698: 5674: 5585: 5484: 5189: 5053: 4847: 4841: 4791: 4743: 4734: 4131: 3637:and an orbiting body, such as a 3275: 3263: 3197: 3113: 2974: 2923:or an object within the Earth's 2829: 2556: 2513: 2439:International Astronomical Union 2418: 2343: 2035: 1989: 1961: 1627: 1609: 1504: 1206:and in other forms of shorthand. 918: 885: 811: 390: 383: 16934:Cellular and molecular biology 15938:, European Southern Observatory 15330: 15313:The Cambridge Double Star Atlas 15248: 15124:"Gcal 4.1: Appendix N Glossary" 14857:The Astronomical Almanac Online 14712:United States Naval Observatory 14700: 14352:List of astronomical catalogues 14198: 13975: 13813: 13776:, as measured from the nearest 13743: 13696: 13534: 13527: 13501: 13481:is low, the result is that the 13316: 13173: 13110: 12924: 12896: 12890: 12857:. The name originated from the 12830: 12796: 12746: 12572: 12362: 12331: 12210: 12141: 11866: 11808: 11678: 11609: 11369: 11096: 11034: 10960: 10730: 10660: 10556: 10523: 10491: 10259: 10092: 9824:cleared its neighbouring region 9753:longitude of the ascending node 9668: 9620: 9483: 9337: 9085:One of two points at which the 9077: 8933: 8863: 8656: 8586: 8400: 8370: 8324: 8128: 8108: 8050: 7761:nor originally classified as a 7735: 7663: 7612: 7482: 7465:A solid piece of debris from a 7446: 7376:One of a set of 110 "nebulous" 7267: 7233: 7133: 7075: 7041: 6821:longitude of the ascending node 6742: 6415: 6392: 6223: 6188: 5942:A system consisting of a large 5923: 5917: 5747: 5650: 5622: 5576: 5490: 5360: 5354: 5339: 5247:geosynchronous equatorial orbit 5229: 5223: 4981:A collective name for the four 4930: 4656: 4580: 4327:, used as a reference point in 4266:, used as a reference point in 4214:or other instrument to take an 4160: 3942: 3498:orbit the Sun with only slight 3423: 3390: 3306: 3204: 3084: 2478: 2355: 2319: 2101: 2034:, i.e. generally inward of the 2017: 1858: 1813: 1621: 1564: 1530:. The barycenter is one of the 1497: 1338: 1272: 936: 867: 679:to describe an orbit. Contrast 670:longitude of the ascending node 414: 320: 270: 247: 219: 185: 175:Harvard spectral classification 146: 15038:Oxford Dictionary of Astronomy 14218:and a companion star are in a 14098: 13923:and their contents, including 13915:1. The entirety of 13812:between the mass or intrinsic 13798:used to characterize an orbit. 13765: 13619: 13590:restricted three-body problems 13520: 13448: 13404: 13386: 13150: 13116: 13040: 13014:in which an object orbits its 12930: 12861: 12729: 12466: 12371: 12120: 11848: 11712: 11534: 11521: 11408: 11249:precession of the Earth's axis 11246:of the Earth–Moon system, and 11161: 11102: 11095:A phenomenon which causes the 10934: 10876: 10635: 10418:of revolution and rotation at 10356: 10347: 10158: 10050: 9935: 9708: 9659: 9527:. It can be determined from a 9463: 9395: 9349: 8908:, such as the trajectory of a 8768: 8749: 8600: 8448:The appearance of the Earth's 8096: 7897: 7699: 7651: 7618: 7586: 7556: 7529: 7510: 7488: 7422: 7261: 6925: 6917:Of or relating to the Earth's 6898: 6857:used to characterize an orbit. 6809: 6790: 6713:in vacuum would travel in one 6517:, extending between 30 and 50 6464: 6117: 6087: 6043: 5965: 5936: 5873: 5842: 5794:, the angular distance on the 5723: 5710: 5607: 5554: 5510: 5394: 5307:about the Earth, i.e. with an 5217: 5167: 5143: 5065: 5059: 5022: 4883: 4876:. Most of the galaxies in the 4807: 4759: 4727: 4643:The region at the center of a 4563: 4526: 4493: 4454: 4386: 4362: 4209: 4200: 4010: 3901:gravitational potential energy 3794: 3755:astronomical coordinate system 3449:astronomical coordinate system 3422:(green), which is permanently 3181: 3170: 3059:extended scattered disc object 2936: 2842: 2796: 2698: 2535: 2470:. It can be observed during a 2394:A phenomenon during which two 2386: 2214: 1875: 1696: 1600: 1587: 1550:where the mass of the central 1503:external to both, as usual in 1444:. Axial tilt is distinct from 1398: 1187: 1181: 896:extreme-environment adaptation 792: 786: 730: 600:used to characterize an orbit. 589: 536: 438: 164: 13: 1: 16014: 15972:International Comet Quarterly 15904:, NASA/IPAC, January 10, 2006 15591:"Components of the Milky Way" 14479:Astrophysical Journal, Part 1 14372: 13677: 13570: 13533:The gradual reduction of the 13329: 13241: 13137:visible in the second body's 12889:One of a class of very large 12689: 12560: 11988: 11957: 11924: 11905: 11730: 11585: 11482: 11160:is a satellite galaxy of the 10476: 10432:A highly magnetized rotating 10190: 10044: 9612: 9596: 9558: 9427: 9266:mean-motion orbital resonance 9207: 8941: 8879: 8825:hypothesized to surround the 8802: 8694: 8296: 8135: 8122: 7717: 7440: 7349: 7164: 7040:. Examples of MACHOs include 6859: 6845:, as measured on a specified 6796: 6625:and is commonly exploited by 6494: 6357:A physical state in which an 6246: 6194: 6022: 5867: 5807: 5780: 5598: 5574:that is the shape of the Sun. 5496: 5160:The point projected upon the 5134: 4948: 4469:The apparent uncommonness of 4461: 4453:. Most flare stars are faint 4423: 4176: 4093: 3965: 3878: 3619: 3469: 3213: 2763:along a circular path on the 2752: 2645: 2621: 2582: 2444: 2299:margin of observational error 2053: 1926: 1852: 1851:around the Sun, known as the 1819: 1638: 1620:orbiting around their common 1512: 1405: 1382: 1360: 1318: 1170: 1050: 986: 846: 542: 368:) compared to adjacent areas. 339:(center) is a prominent dark 141: 15678:Astronomy & Astrophysics 15283:Kutner, Marc Leslie (2003), 15255:Moulton, Forest R. (1970) , 14909:Astronomy & Astrophysics 13718: 13488: 13465:The net result of continued 13254: 13070: 13015: 12915: 12453: 11552: 11215: 11040: 10891: 10861:equatorial coordinate system 10809: 10767: 10390: 10284: 10183: 10136: 10002: 9839: 9629: 9551: 9533: 9426:. Most of the volume of the 9378: 9371:The hypothetical, idealized 9294: 9197: 8963: 8712: 8646: 8440: 8207: 8200: 8157:An early classification for 8037: 7797: 7625: 7473: 7457: 7343: 7094: 6668: 6506: 6314: 6308:, which are thought to form 6297: 5983: 5800:measured westward along the 5458:gravitational-wave astronomy 5269: 5116: 5078: 4668: 4330:celestial coordinate systems 4269:celestial coordinate systems 4146:in particular, faculae (see 4136:formed by concentrations of 3817: 3801: 3763: 3747:equatorial coordinate system 3645: 3430: 3380:celestial coordinate systems 3077:in the outer reaches of the 2853:equatorial coordinate system 2774: 2715:The apparent movement of an 2640:The scientific study of the 2632: 2612: 2258:radiating away from the Sun. 2112:chromospheric activity index 1969:equatorial coordinate system 1809:equatorial coordinate system 1801: 1423: 1241: 1152: 908:, the possible existence of 530: 468: 431: 7: 15954:HubbleSite – Reference Desk 15932:"ESO Astronomical Glossary" 15920:, Sky & Telescope Media 15732:The Classification of Stars 15708:10.1051/0004-6361/201015809 15564:Husser, Tim-Oliver (2012), 14939:10.1051/0004-6361/201629126 14685:10.1088/0067-0049/187/1/228 14542:10.1051/0004-6361:200810377 14393:Mitton, Jacqueline (2007), 14340: 14304:, the apparent path of the 14259:Hertzsprung–Russell diagram 14181: 14171: 14055: 13936: 13924: 13907: 13893: 13840: 13582: 13560: 13514: 13419: 13344: 13194: 13188: 13144: 13048: 12908: 12848: 12776: 12643: 12544: 12519: 12441: 12419: 12407: 12379: 12352: 12270:and, less importantly, the 12253: 12184: 12040: 12021: 12015: 11887: 11801: 11707: 11652: 11447:as observed from the Earth. 11342: 11326: 11286: 11185: 11147: 10968: 10903: 10816:inertial frame of reference 10721: 10697:Hertzsprung–Russell diagram 10541: 10406:pseudo-synchronous rotation 10368: 10291:inertial frame of reference 10274: 10241: 10227:precession of the equinoxes 10207:precession of the equinoxes 10101: 10078: 10026: 9970: 9960: 9941: 9887: 9881: 9861: 9846: 9725: 9588: 9541: 9531:of the stellar variability. 9455: 9403: 9137: 8947: 8909: 8810: 8672: 8565: 8536:orbits and 180 degrees for 8481: 8389: 8382: 8261: 8239: 8215: 8194: 8151: 8058: 8027: 8009: 7983: 7948: 7928: 7841: 7756: 7755:that is neither a dominant 7639: 7605:A stellar object such as a 7504: 7466: 7408: 7355: 7329: 7314: 7300:mean-motion resonance (MMR) 7206: 7190: 7141:Hertzsprung–Russell diagram 7081: 7014:Massive compact halo object 6981: 6975: 6933: 6874: 6748: 6736: 6641: 6562: 6500: 6472: 6423: 6325:Hertzsprung–Russell diagram 6209: 6164: 5943: 5901:Hertzsprung–Russell diagram 5829: 5773: 5731: 5644:Hertzsprung–Russell diagram 5627:emanating from the Earth's 5519: 5348: 5244: 5210:The position of an object ( 5173: 4938: 4899: 4779: 4753: 4703: 4683: 4644: 4630: 4568: 4498: 4470: 4370: 4245: 4169: 4080: 4070: 4055: 4015: 3962:for stars of different mass 3926:Hertzsprung–Russell diagram 3871: 3717: 3643:, as it appears from Earth. 3638: 3564: 3533: 3487: 3332: 3324: 3152: 3052: 3007: 2954: 2948: 2860:. Coordinates north of the 2734: 2706: 2665: 2572: 2566:cosmic microwave background 2543: 2507: 2327: 2188: 2116:A parameter indicating the 2082: 1897: 1669: 1578: 1557: 1479:spherical coordinate system 1413: 1394:precession of the equinoxes 1343:) in the orientation of an 1288:to determine the nature of 1130: 1124: 1090: 1071: 1038: 1016: 944: 875: 763:, i.e. one that orbits the 743: 715: 696: 673:, is used along with other 640: 563: 484: 422: 398: 363: 310: 264: 213: 10: 17112: 17035:Probability and statistics 15792:10.1051/0004-6361:20030163 15762:Astronomy and Astrophysics 15737:Cambridge University Press 15618:Barnes, Rory, ed. (2010), 15464:Ridpath, Ian, ed. (2018), 15439:Astronomy and Astrophysics 15339:Astronomy and Astrophysics 15263:: Dover, pp. 322–23, 15240:Aitken, Robert G. (1935), 14556:Perryman, Michael (2009), 14521:Astronomy and Astrophysics 14357:List of astronomy acronyms 14114:electron-degenerate matter 13701:from the two objects, the 13662: 13576: 13545:due to tidal interactions. 13038:as the primary's rotation. 13032:of the primary and in the 13009: 12966:gravitational acceleration 12528:The outermost region of a 12491: 12425: 12264:gravitational acceleration 12033: 12032:, and the plasma tails of 11911: 11874:The gravitationally bound 11614:to its orbital plane. One 11222: 11200:, color, or position of a 11039:, which describes the net 10617:gravitational perturbation 10544:quasi-stellar radio source 10233: 10167: 10008: 9804: 9635: 9566: 9393:at a given moment in time. 9331: 9235: 9185: 9153: 9092: 9049: 9005: 8983: 8957: 8849: 8706: 8700: 8509: 8302: 8255: 8193:exactly opposite from the 7920: 7762: 7744: 7656:, formed from billions of 7644:that includes the Earth's 7522: 7516: 7434: 7383: 7296:mathematically convenient. 7156:in their core region. The 7127: 6834: 6833:, and the direction of an 6784: 6727:) or 5.88 trillion miles ( 6586: 6462:that may exist in reality. 6433: 6409:Kelvin–Helmholtz mechanism 6386: 6212:Laplace's invariable plane 5934:and hydrogen-fusing stars. 5806:from the observer's local 5760: 5537:spectral lines of hydrogen 5524:powered by young, massive 5382: 5376: 5347:Any very large or massive 4709: 4607:galactic coordinate system 3908: 3808: 3708: 3441:ecliptic coordinate system 3139:The apparent motion of an 2991:and have suffered extreme 2917:that is not an individual 2594:consisting of high-energy 2208:clearing the neighbourhood 2200:cis-Neptunian object (CNO) 2059: 2002: 1614:consisting of exactly two 1525: 1461: 973:gravitational perturbation 780: 611: 577: 518: 499: 370: 235: 16805: 16728: 16520: 16497:Large Binocular Telescope 16462:Extremely Large Telescope 16455:Extremely large telescope 16428: 16311: 16251: 16172: 16134: 16095: 16088: 16022: 15815:The Astrophysical Journal 15516:Kepler Mission Star Field 15467:A Dictionary of Astronomy 15096:Westlake, Hannah (2015), 14954:The Astrophysical Journal 14765:A Dictionary of Astronomy 14317: 14278: 14263: 14231: 14147:absolute visual magnitude 14121: 13998: 13930: 13725: 13508: 13494: 13350: 13338: 13303:, approximately 75 to 90 13270: 13207: 13086: 12982:meters per second squared 12936: 12683: 12554: 12529: 12498: 12460: 12424:and other bodies such as 12389: 12308:held together by its own 11901:small Solar System bodies 11841: 11767: 11646: 11261: 11201: 11002: 10789: 10533: 10509: 10424: 10125:small Solar System bodies 10014: 9915:planetary differentiation 9886:-like geology, such as a 9790: 9575: 9494:. The word "parsec" is a 8915: 8711:around the Sun (or other 8633: 8487: 8475: 8331: 8115:electromagnetic radiation 8090:multi-messenger astronomy 8068: 7885: 7657: 7400: 7361: 7087: 6943: 6918: 6868: 6677: 6596:of the large bodies, the 6490:small Solar System bodies 6234:and perpendicular to its 6158: 5662: 4852:, each of which orbits a 4823: 4814: 4579:of 4.100 ± 0.034 million 4398: 4183: 4125: 4116: 4049: 3983:electromagnetic radiation 3930: 3732:and equidistant from its 3520:electromagnetic radiation 3495:small Solar System bodies 3222: 3190: 3158: 2918: 2740: 2728: 2496:A significant release of 2452: 1891: 1727:gravitational contraction 1654: 1615: 1551: 1473:. When combined with the 1366: 1044: 1032: 995: 842:small Solar System bodies 776:small Solar System bodies 724: 702: 689: 553:have exactly two apsides. 455: 446: 291: 280: 241: 201: 16469:Gran Telescopio Canarias 15259:(2nd revised ed.), 15156:, www.tawarikhkhwani.com 14985:10.3847/1538-4357/aafac8 14305: 14287: 14240: 14165: 13690: 13310: 13297:The boundary within the 13200: 13166: 12620:of gases encompassing a 12209:and the measurements of 12129:. This is caused by the 12055: 12049: 12009: 11945: 11939: 11881: 11825: 11789: 11747: 11640: 11584:(e.g. to cross the same 11579: 11573: 11470: 11429:of an object within the 11402: 11396: 10750:orbit with little or no 10575:electromagnetic spectrum 10497: 10455:quadratic field strength 9969:The scientific study of 9605: 9288: 9212:, is commonly used as a 9048:The tilt of an object's 8902:curved trajectory of an 8890: 8826: 8459: 8449: 8423: 8318: 8179: 7903: 7836:moment of inertia factor 7750: 7676: 7323: 7162:is a main-sequence star. 7157: 6955: 6911: 6764: 6690:to be visible along the 6524: 6078: 5628: 5591: 5565: 4785: 4726:about the center of the 4443:electromagnetic spectrum 4404: 4343: 4288: 4141: 4042:that exists outside the 3829: 3673: 3666: 3632: 3459: 3354: 3234: 3146: 2722: 2599: 2501: 2465: 2241: 2232: 2228:electromagnetic spectrum 1983: 1943: 1736: 1372: 1249:The scientific study of 764: 729:recognizable in Earth's 708: 509: 407: 380:chemically peculiar star 277:electromagnetic spectrum 17096:Astronomy-related lists 16830:Artificial intelligence 16564:Astrology and astronomy 16274:Gravitational radiation 15898:"Astronomical Glossary" 15784:2003A&A...401..997P 15700:2011A&A...528A..27H 15649:Sanders, Jason (2015), 15451:1986A&A...165..135R 15351:1981A&A....99..126H 15083:1982A&AS...48..503R 14931:2017A&A...597A..29S 14642:, Infobase Publishing, 14533:2009A&A...493.1099S 14450:Walker, Gordon (1987), 14270:hydrostatic equilibrium 14189:active galactic nucleus 13689:across the face of the 13051:synodic rotation period 12883:supermassive black hole 12723:submillimetre astronomy 12639:stellar evolution model 12547:spectral classification 12292: 12196:observational astronomy 12090:spectral classification 11545:small Solar System body 11154:gravitational potential 11152:that orbits within the 11024:Rosseland optical depth 11001:directly rather than a 10570:supermassive black hole 10552:active galactic nucleus 10472:magnetic field strength 9878:hydrostatic equilibrium 9268:, in which the bodies' 9097:intersects a specified 8737:observational astronomy 8641:stellar classifications 8495:observational astronomy 8292:small Solar System body 8275:small Solar System body 8272:, or sometimes another 8048:and the east direction. 7935:minor natural satellite 7870: 7852: 7388:by French comet hunter 7146:hydrostatic equilibrium 6684:Moon's elliptical orbit 6529:. It is similar to the 6021:), especially chemical 5896:Gamma Doradus variables 5466:observational astronomy 4941:group of galaxies (GrG) 4768:galactocentric distance 4664:active galactic nucleus 4652:supermassive black hole 4576:supermassive black hole 4506:extragalactic astronomy 4409:, as well as all other 4004:extragalactic astronomy 3096:trans-Neptunian objects 3055:distant detached object 2932:observational astronomy 2371:compact stellar nucleus 2157:, after correction for 2096:compact stellar nucleus 2090:supermassive black hole 2013:small Solar System body 1357:Earth's rotational axis 713:, as viewed from Earth. 257:active galactic nucleus 17060:Structural engineering 17000:Mechanical engineering 16973:Western and South Asia 16483:Hubble Space Telescope 14419:Maeder, Andre (2008), 14250:zero-age main sequence 14093:stellar classification 14026:statistical dispersion 13888:UBV photometric system 13835:cosmic distance ladder 13810:empirical relationship 13705:can be used to detect 13655:trans-Neptunian object 13650: 13277:telluric contamination 12821: 12816:planetary-mass objects 12669:stellar magnetic field 12553:The categorization of 12539:stellar classification 12165: 12099:stellar classification 11968:is distinguished from 11605:not perfectly circular 11498: 11212:atmospheric refraction 11158:Large Magellanic Cloud 11031:extinction coefficient 10848: 10531: 10461:stellar magnetic field 10400:pre-main-sequence star 10067:, among other objects. 9961:Also sometimes called 9655:atmospheric resistance 9461: 9316: 9152:takes to complete one 9038: 9031:(yellow) intersects a 8418:, which are a type of 7715: 7002: 6900:astronomical magnitude 6644:Lenakaeia Supercluster 6182:interstellar reddening 5912:hydrogen burning limit 5453: 5410:gravitational collapse 5196:diffusively scattering 4708:takes to complete one 3963: 3617: 3538:with an approximately 3436: 3383:. It differs from the 3377:bodies within various 2994:gravitational collapse 2840: 2837:Hubble Space Telescope 2529:cosmic distance ladder 2366:with very small radii. 2075:central massive object 1994:. It is the basis for 1864: 1592:for the origin of the 1510: 1203:astronomical constants 1066:astronomical catalogue 570:argument of pericenter 352: 275:over some part of the 136: 133: 130: 127: 124: 121: 118: 115: 112: 109: 106: 103: 100: 97: 94: 91: 88: 85: 82: 79: 76: 73: 70: 67: 64: 61: 17086:Glossaries of science 16925:Environmental science 16810:Aerospace engineering 16587:Astroparticle physics 16322:Australian Aboriginal 15626:John Wiley & Sons 15035:Ridpath, Ian (2007), 14853:"Section M: Glossary" 14762:Ridpath, Ian (2012), 14367:Modern constellations 14324:Zodiac constellations 13941:, all other forms of 13900:Johnson–Morgan system 13803:Tully–Fisher relation 13640: 13550:Tisserand's parameter 13400:thick disk population 13371:thick disk population 13360:theoretical astronomy 13230:The component of the 13026:equal to the average 12813:, as well as certain 12154: 11091:rotational modulation 10992:planetary-mass object 10838: 10708:main-sequence turnoff 10520: 10244:gravitational primary 10072:planetary-mass object 10007:objects in or out of 9901:planetary-mass object 9511:partial solar eclipse 9478:shift of exactly one 9445: 9391:orbital state vectors 9305: 9204:Earth's orbital plane 9016: 8763:theoretical astronomy 8433:New General Catalogue 7890:on Earth; because of 7690: 6992: 6636:Laniakea Supercluster 6602:Coriolis acceleration 6475:Edgeworth–Kuiper belt 6278:following a distant, 5658:effective temperature 5440: 5432:gravitational lensing 5287:Artificial satellites 3953: 3837:plane of the ecliptic 3726:perpendicular to its 3684:celestial coordinates 3662:artificial satellites 3607: 3509:effective temperature 3471:plane of the ecliptic 3406:plane of the ecliptic 3401: 3339:plane of the ecliptic 2826: 2490:coronal mass ejection 2404:have either the same 2315:gravitationally bound 2099:, but sometimes both. 2087:, typically either a 2049:cis-Neptunian objects 2028:between those of the 1911:artificial satellites 1830: 1730:and by the fusion of 1494: 1058:astronomical "object" 916:, among other topics. 910:extraterrestrial life 806:distant minor planets 566:argument of perifocus 558:argument of periapsis 487:visual brightness (V) 335: 32:glossary of astronomy 16579:Astronomers Monument 16511:Very Large Telescope 16058:Astronomical symbols 15974:, Harvard University 14708:Astronomical Almanac 14347:Outline of astronomy 14226: 14160: 14075: 13984: 13880: 13676:across a particular 13493:. An example is the 13478:orbital eccentricity 13380:thin disk population 13219: 12990:, which is equal to 12763:artificial satellite 12737:astronomical objects 12497:Of or relating to a 12388:Any small number of 12320:thermonuclear fusion 12300:A massive, luminous 12187:positional astronomy 12108:spectroscopic binary 12008:, released from the 11698:magnetic field lines 11520:. In the context of 11146:A smaller companion 11119: 10928:circumplanetary disk 10759:orbital eccentricity 10643:astronomical objects 10622:Beta Cephei variable 10612:Doppler spectroscopy 10597: 10561:is generated by the 10448: 10311:projected separation 10113:protoplanetary disks 9946:. An example is the 9880:and therefore has a 9845:Of or relating to a 9819:thermonuclear fusion 9583:artificial satellite 9525:cataclysmic variable 9436: 9206:, which defines the 8977:orbital eccentricity 8745:astronomical objects 8595: 8547:nuclear star cluster 8146: 8104:astronomical objects 8067:A loose grouping of 7941:An especially small 7743:An object in direct 7445:through the Earth's 7379:astronomical objects 7138:, in particular the 7006: 6594:gravitational forces 6549: 6401: 6344: 6328:that represents the 6125:astronomical objects 5978: 5661:for a population of 5546:and in star-forming 5505: 5334:geostationary orbits 5295:geosynchronous orbit 5265:geosynchronous orbit 5030:astronomical objects 4775:gravitational center 4479: 4382:astronomical objects 4379:The "background" of 4357:First Point of Aries 4315:The location of the 4310:First Point of Libra 4302:First Point of Libra 4254:The location of the 4239:First Point of Aries 4225:first magnitude star 4188:that lies along the 4182:A randomly situated 4138:magnetic field lines 4111: 4085:outside the Earth's 3656:astronomical objects 3582:orbital eccentricity 3318:orbital eccentricity 3284: 3268:as well as low-mass 2791: 2604:or from outside the 2518:or present during a 2512:, often following a 2397:astronomical objects 2380:nuclear star cluster 2293:common proper motion 2145:is the ratio of the 1887:astronomical objects 1778:reflecting telescope 1747: 1485: 1308:chemical composition 1291:astronomical objects 1148:astronomical objects 1074:astronomical catalog 980:spectroscopic binary 707:with respect to the 605:artificial satellite 463:artificial satellite 159: 16652:List of astronomers 16065:Astronomical object 15837:2004ApJ...612..724Y 15378:2009MNRAS.394.1338B 15227:2005ASPC..335....3S 15188:1981PASP...93..681M 15017:1978IAUS...79...51E 14976:2019ApJ...871..227F 14894:1964SvA.....7..618C 14733:John Wiley and Sons 14676:2010ApJS..187..228S 14607:2004MNRAS.350..189T 14491:1984ApJ...279..763N 14180:A seemingly normal 14135:Wilson–Bappu effect 14112:composed mostly of 14019:velocity dispersion 13964:observable universe 13645:total solar eclipse 13630:total solar eclipse 13563:Tisserand parameter 13324:interstellar medium 13315:, beyond which the 13234:of a star or other 13226:tangential velocity 12788:astronomical object 12742:terahertz radiation 12582:stellar designation 12487:Orion constellation 12179:spherical astronomy 11965:apparent solar time 11752:, or approximately 11566:on Earth, i.e. the 11133:total solar eclipse 10971:interstellar planet 10753:orbital inclination 10706:. It begins at the 10671:astronomical object 10487:ecliptic longitudes 10384:protoplanetary disk 10364:protoplanetary disk 10144:Another name for a 9404:Also simply called 9358:origin of longitude 9149:astronomical object 9043:orbital inclination 8757:observable universe 8728:observable universe 8632:A group of massive 8527:orbital inclination 8342:astronomical object 8119:gravitational waves 8061:stellar association 7248:The fraction of an 7109:astronomical object 6882:astronomical object 6830:origin of longitude 6628:man-made satellites 6147:interstellar medium 6055:orbital inclination 5886:This is a class of 5822:containing Earth's 5743:astronomical object 5618:interstellar medium 5475:gravitational waves 5399:. They differ from 5239:geostationary orbit 5219:center of the Earth 5092:composed mainly of 5016:gamma-ray astronomy 4910:and other types of 4879:observable universe 4784:. For example, the 4750:gravitational field 4699:astronomical object 4514:galactic anticenter 4284:ecliptic coordinate 4232:apparent magnitudes 4124:A bright spot on a 4039:astronomical object 3988:astronomical object 3958:evolutionary tracks 3858:, occur on or near 3696:astronomical object 3551:lenticular galaxies 3142:astronomical object 2969:A star composed of 2914:astronomical object 2835:as detected by the 2785:time of culmination 2718:astronomical object 1997:spherical astronomy 1869:celestial mechanics 1634:optical double star 1595:observable universe 1447:orbital inclination 1313:celestial mechanics 1140:astronomical symbol 1102:observable universe 1085:astronomical object 1028:observable universe 317:diffusely reflected 187:the mass of the Sun 178:system, a class of 48:atmosphere of Earth 16638:Physical cosmology 14295:celestial latitude 14058:Local Supercluster 14049:Virgo Supercluster 14010:or its profile of 13708:extrasolar planets 13651: 13649:as seen from Earth 13422:tidal acceleration 13281:Earth's atmosphere 13069:) relative to the 12658:model of a star's 12614:2. The 12608:stellar atmosphere 12514:stellar atmosphere 12207:spherical geometry 12166: 12029:geomagnetic storms 11919:natural satellites 11244:tidal acceleration 10849: 10674:that emits strong 10532: 10328:astronomical units 10317:angular separation 10220:general relativity 10212:Apsidal precession 9720:plane of reference 9702:photometric system 9491:astronomical units 9462: 9317: 9243:orbital parameters 9215:plane of reference 9124:non-inclined orbit 9100:plane of reference 9063:plane of reference 9039: 8970:frame of reference 8521:plane of reference 8503:non-inclined orbit 8420:subatomic particle 8348:interstellar cloud 7829:molecular hydrogen 7824:interstellar cloud 7716: 7633:1. The 7338:meridian astronomy 7003: 6997:phases of the Moon 6848:plane of reference 6696:of the lunar disk. 6648:Local Supercluster 6484:circumstellar disc 6432:The motion of one 6360:interstellar cloud 6337:evolutionary track 6111:infrared astronomy 5951:satellite galaxies 5906:instability strips 5670:absolute magnitude 5549:irregular galaxies 5454: 5445:gravitational lens 5419:gravitational lens 5206:geometric position 4888:, are much larger. 4573:, consisting of a 4487:galactic astronomy 4217:astronomical image 4023:galactic astronomy 3964: 3918:evolutionary track 3734:geographical poles 3629:angular separation 3618: 3437: 3271:substellar objects 3025:plane of reference 2887:circumstellar disc 2841: 2807:circumstellar disc 2685:circumstellar disc 2413:ecliptic longitude 2191:circumstellar disk 2183:circumstellar disc 1919:celestial meridian 1865: 1848:plane of its orbit 1764:coudé spectrograph 1589:cosmological model 1511: 1235:10 parsecs; 1.5813 1166:phases of the Moon 959:astrometric binary 905:extrasolar planets 859:main asteroid belt 822:circumstellar disc 695:The position of a 658:plane of reference 576:The angle from an 479:apparent magnitude 353: 209:apparent magnitude 195:absolute magnitude 17073: 17072: 17055:Scientific naming 17045:Quantum computing 16875:Computer hardware 16870:Clinical research 16865:Civil engineering 16760: 16759: 16645:Quantum cosmology 16631:Planetary geology 16424: 16423: 16135:Celestial subject 15261:Mineola, New York 14406:978-0-521-82364-7 14239:The point in the 14128:Type Ia supernova 14034:or galaxies in a 13864:nautical twilight 13783:eccentric anomaly 13385:The layer of the 13292:termination shock 13237:astronomical body 13029:rotational period 13003:synchronous orbit 12971:astronomical body 12947:stages or when a 12771:substellar object 12661:stellar evolution 12631:stellar evolution 12559:based upon their 12415:planetary systems 12339:emission spectrum 12272:centrifugal force 11974:. Solar time and 11860:geomagnetic storm 11654:precisely aligned 11611:not perpendicular 11338:celestial equator 11329:southward equinox 11321:September equinox 11010:substellar object 10911:satellite systems 10899:astronomical body 10871:celestial equator 10868:. It divides the 10803:retrograde motion 10741:natural satellite 10648:radio frequencies 10414:, this is a near 10303:retrograde motion 9984:planetary systems 9955:planetary science 9801:astronomical body 9311:orbital resonance 9229:orbital resonance 9193:astronomical body 9146:The time a given 9140:revolution period 9071:orbital mechanics 8929:elliptical orbits 8923:natural satellite 8779:astronomical body 8576:astronomical body 8530:is 0 degrees for 8518:with a specified 8471:celestial objects 8283:near-Earth object 8251:astronomical body 8234:natural satellite 8187:The point on the 8171:giant ellipticals 8012:MK classification 7969:minor-planet moon 7944:natural satellite 7881:natural satellite 7864:natural satellite 7786:natural satellite 7778:minor-planet moon 7308:orbital resonance 7227:September equinox 7202:celestial equator 7193:Northward equinox 7023:astronomical body 6906:visual brightness 6622:trojan satellites 6598:centripetal force 6352:Jeans instability 6275:natural satellite 5958:) as well as its 5863:celestial equator 5803:celestial equator 5316:rotational period 5313:equal to Earth's 5304:synchronous orbit 5156:geocentric zenith 4907:galactic clusters 4796:(approximately 8 4696:The time a given 4439:magnetic activity 4351:celestial equator 4333:. Located in the 4318:September equinox 4296:celestial equator 4272:. Located in the 4065:extrasolar planet 4031:extrasolar object 3783:primary direction 3777:celestial equator 3760:fundamental plane 3739:celestial equator 3527:elliptical galaxy 3477:primary direction 3466:fundamental plane 3386:celestial equator 3239:, in contrast to 3163:) around the two 2971:degenerate matter 2863:celestial equator 2781:lower culmination 2771:upper culmination 2692:break-up velocity 2680:Newtonian gravity 2676:centrifugal force 2668:break-up velocity 2661:critical velocity 2654:critical rotation 2442:in 1930. Compare 2339:astronomical body 2118:magnetic activity 1954:"intersects" the 1880:that studies the 1841:celestial equator 1812:. Due to Earth's 1785:celestial equator 1707:substellar object 1692:Newtonian gravity 1688:centrifugal force 1680:critical rotation 1674:critical velocity 1665:break-up velocity 1362:its orbital plane 1346:astronomical body 1252:celestial objects 1211:astronomical unit 1108:astronomical body 1011:astronomical body 947:planetary geology 930:orbital mechanics 626:natural satellite 550:elliptical orbits 306:astronomical body 44:celestial objects 18:Nadir (astronomy) 16:(Redirected from 17103: 16880:Computer science 16787: 16780: 16773: 16764: 16763: 16753: 16749: 16748: 16741: 16737: 16736: 16721: 16712: 16705: 16698: 16691: 16682: 16675: 16668: 16666:Medieval Islamic 16661: 16654: 16647: 16640: 16633: 16626: 16619: 16610: 16603: 16596: 16589: 16582: 16573: 16566: 16559: 16552: 16550:Astroinformatics 16545: 16538: 16531: 16529:Archaeoastronomy 16513: 16506: 16499: 16492: 16490:Keck Observatory 16485: 16478: 16471: 16464: 16457: 16450: 16443: 16417: 16408: 16401: 16394: 16387: 16385:Medieval Islamic 16380: 16373: 16366: 16359: 16352: 16345: 16338: 16331: 16324: 16304: 16297: 16290: 16283: 16276: 16269: 16262: 16244: 16235: 16228: 16221: 16214: 16212: 16204: 16202: 16190: 16183: 16163: 16156: 16149: 16127: 16120: 16113: 16106: 16093: 16092: 16081: 16074: 16067: 16060: 16053: 16044: 16037: 16030: 16009: 16002: 15995: 15986: 15985: 15981: 15980: 15979: 15963: 15962: 15961: 15945: 15944: 15943: 15927: 15926: 15925: 15911: 15910: 15909: 15884: 15883: 15863: 15857: 15856: 15830: 15828:astro-ph/0401117 15810: 15804: 15803: 15777: 15775:astro-ph/0301637 15757: 15751: 15750: 15726: 15720: 15719: 15693: 15673: 15667: 15666: 15646: 15640: 15639: 15615: 15609: 15608: 15607: 15606: 15587: 15581: 15580: 15561: 15555: 15554: 15534: 15528: 15527: 15525: 15524: 15511: 15505: 15504: 15502: 15501: 15488: 15482: 15481: 15461: 15455: 15454: 15445:(1–2): 135–156, 15433: 15427: 15426: 15406: 15400: 15399: 15389: 15372:(3): 1338–1350, 15361: 15355: 15354: 15334: 15328: 15327: 15307: 15301: 15300: 15280: 15274: 15273: 15252: 15246: 15245: 15242:The Binary Stars 15237: 15231: 15230: 15214: 15208: 15207: 15171: 15165: 15164: 15163: 15161: 15145: 15139: 15138: 15137: 15135: 15119: 15113: 15112: 15093: 15087: 15086: 15066: 15060: 15059: 15032: 15021: 15020: 15004: 14998: 14997: 14987: 14969: 14949: 14943: 14942: 14924: 14904: 14898: 14897: 14882:Soviet Astronomy 14877: 14871: 14870: 14869: 14868: 14849: 14814: 14813: 14812: 14811: 14796: 14790: 14789: 14787: 14786: 14759: 14753: 14752: 14750: 14749: 14722: 14716: 14715: 14714:, 2008, Glossary 14704: 14698: 14697: 14687: 14659: 14653: 14652: 14635: 14629: 14628: 14618: 14600: 14598:astro-ph/0312113 14580: 14574: 14573: 14553: 14547: 14546: 14544: 14527:(3): 1099–1107, 14518: 14509: 14503: 14502: 14474: 14468: 14467: 14447: 14441: 14440: 14416: 14410: 14409: 14390: 14320: 14314: 14313:celestial sphere 14308: 14302: 14296: 14290: 14286:The area of the 14266: 14260: 14243: 14190: 14184: 14177: 14154: 14150:of the emitting 14148: 14124: 14110: 14094: 14069: 14038: 14037:galactic cluster 14032: 14031:globular cluster 14008: 14001: 13978: 13965: 13939: 13933: 13927: 13903: 13872:two-body problem 13865: 13859: 13853: 13836: 13826:angular velocity 13822: 13816: 13796: 13795:orbital elements 13790: 13784: 13774: 13773:elliptical orbit 13768: 13759: 13755: 13751: 13721: 13715: 13709: 13699: 13693: 13687:transit of Venus 13680: 13674: 13673:celestial object 13646: 13615: 13609: 13603: 13597: 13596:orbital elements 13591: 13585: 13579: 13573: 13566: 13555: 13543: 13537: 13523: 13517: 13511: 13497: 13491: 13485: 13479: 13473:angular momentum 13469: 13444: 13438: 13437:rotation periods 13432: 13425: 13407: 13401: 13395: 13389: 13353: 13347: 13341: 13325: 13319: 13313: 13307: 13301: 13273: 13250: 13244: 13238: 13203: 13197: 13191: 13185: 13169: 13159: 13153: 13147: 13141: 13140:celestial sphere 13135: 13134:background stars 13119: 13113: 13107: 13101: 13095: 13089: 13079: 13073: 13067: 13061: 13054: 13036: 13030: 13024: 13018: 13012: 12997: 12995: 12988: 12987:standard gravity 12978: 12972: 12951: 12945: 12939: 12933: 12927: 12911: 12905: 12899: 12893: 12875: 12864: 12851: 12817: 12811: 12810:stellar remnants 12805: 12799: 12789: 12782: 12764: 12758: 12738: 12732: 12728:The subfield of 12705:stellar parallax 12698: 12692: 12686: 12662: 12656: 12649: 12624: 12618: 12609: 12600:stellar envelope 12591:stellar dynamics 12575: 12569: 12563: 12557: 12550: 12532: 12525: 12522:stellar envelope 12507: 12501: 12475: 12474:celestial sphere 12469: 12463: 12444: 12435:starburst galaxy 12428: 12422: 12418:, which include 12416: 12410: 12404: 12398: 12392: 12385: 12358: 12340: 12334: 12316: 12289: 12287: 12281: 12279: 12259: 12248: 12239: 12229:standard gravity 12213: 12203: 12202:celestial sphere 12197: 12190: 12161: 12137: 12123: 12117: 12100: 12083: 12076: 12070: 12064: 12058: 12052: 12036: 12030: 12024: 12018: 12012: 11984: 11978: 11972: 11966: 11960: 11954: 11948: 11942: 11936: 11920: 11914: 11908: 11902: 11896: 11890: 11884: 11878: 11877:planetary system 11861: 11844: 11834: 11828: 11804: 11798: 11792: 11786: 11777:solar prominence 11770: 11765: 11760: 11757: 11750: 11704: 11690: 11674: 11668: 11662: 11655: 11649: 11643: 11637: 11621: 11612: 11606: 11600: 11594: 11588: 11582: 11576: 11570: 11564: 11537: 11530: 11529:celestial sphere 11524: 11518: 11510:, including the 11485: 11479: 11473: 11467: 11461: 11445: 11444:celestial sphere 11439: 11433: 11427: 11411: 11405: 11399: 11393: 11392:celestial sphere 11387: 11381: 11364: 11353:autumnal equinox 11345: 11339: 11332: 11314: 11310:, such as for a 11308: 11303: 11292: 11264: 11250: 11218: 11204: 11198: 11191: 11164: 11150: 11141:satellite galaxy 11134: 11113:BY Dra variables 11105: 11099: 11085: 11079: 11073: 11072:background stars 11069:relative to the 11067: 11066:axis of rotation 11050: 11043: 11037: 11017: 11016:planetary system 11011: 11005: 10999: 10993: 10986: 10952: 10946: 10929: 10918: 10912: 10906: 10900: 10894: 10888: 10872: 10862: 10844: 10829: 10822: 10812: 10783:relativistic jet 10776: 10772:, as opposed to 10770: 10760: 10754: 10748: 10742: 10704: 10703:globular cluster 10698: 10689:red-giant branch 10682: 10672: 10656:radio telescopes 10644: 10638: 10634:The subfield of 10618: 10571: 10565: 10559: 10553: 10546: 10526: 10512: 10506: 10500: 10494: 10488: 10465:root mean square 10442: 10436: 10377: 10371: 10365: 10359: 10335:of the observer. 10329: 10323: 10304: 10297: 10287: 10280: 10262: 10255: 10208: 10202: 10201:axis of rotation 10186: 10180: 10170: 10154: 10148: 10132: 10126: 10120: 10114: 10104: 10088: 10065: 10059: 10053: 10047: 10041: 10035: 10029: 10023: 10017: 10011: 10005: 9992:planetary system 9985: 9979: 9973: 9966: 9944: 9938: 9925:planetary nebula 9908: 9902: 9896: 9890: 9884: 9874: 9867: 9864:planetary object 9849: 9831: 9825: 9807: 9802: 9786: 9778:plane of the sky 9772: 9771:equatorial plane 9766: 9765:invariable plane 9760: 9754: 9748: 9742: 9741:orbital elements 9731: 9687: 9686:superior planets 9677: 9676:Inferior planets 9671: 9650: 9649:two-body problem 9644: 9638: 9632: 9615: 9608: 9591: 9584: 9578: 9561: 9554: 9547: 9492: 9488:or 206,265 9486: 9476: 9458: 9451: 9430: 9420: 9419:celestial bodies 9409: 9387: 9381: 9375: 9366:osculating orbit 9352: 9346: 9340: 9334: 9312: 9297: 9291: 9278: 9272: 9262: 9256: 9250: 9244: 9238: 9222: 9216: 9210: 9200: 9194: 9188: 9168: 9162: 9156: 9150: 9143: 9125: 9119: 9113: 9107: 9101: 9095: 9089: 9064: 9058: 9052: 9035: 9029: 9022: 9021:orbital elements 9008: 8999:orbital elements 8992: 8991:elliptical orbit 8986: 8966: 8960: 8953: 8936: 8932:around a common 8930: 8924: 8918: 8912: 8906: 8875: 8845: 8839:inner Oort cloud 8835: 8829: 8823: 8816: 8798: 8792: 8786: 8780: 8764: 8760:, as opposed to 8758: 8752: 8748:with the use of 8746: 8721: 8715: 8709: 8703: 8697: 8691: 8685: 8678: 8659: 8642: 8636: 8616:scientific model 8589: 8583: 8582:axis of rotation 8577: 8540: 8534: 8528: 8524:, such that the 8522: 8512: 8496: 8490: 8484: 8478: 8472: 8462: 8452: 8426: 8412: 8385: 8379: 8373: 8355: 8349: 8343: 8327: 8326:closest approach 8321: 8315: 8305: 8299: 8293: 8276: 8270: 8264: 8258: 8252: 8245: 8225: 8203: 8197: 8191: 8190:celestial sphere 8163:Seyfert galaxies 8131: 8125: 8111: 8105: 8099: 8083: 8077: 8071: 8064: 8046: 8040: 8033: 8015: 7996: 7978: 7970: 7963: 7957: 7951: 7945: 7938: 7912: 7906: 7900: 7894: 7888: 7882: 7865: 7847: 7825: 7808: 7800: 7793: 7787: 7771: 7765: 7759: 7753: 7747: 7730: 7709: 7702: 7701:Milky Way Galaxy 7695: 7679: 7673: 7666: 7660: 7654: 7648: 7642: 7637: 7621: 7615: 7609: 7595: 7589: 7573: 7559: 7525: 7519: 7513: 7507: 7491: 7485: 7469: 7449: 7443: 7437: 7431: 7425: 7418: 7396: 7395:deep-sky objects 7386: 7380: 7364: 7358: 7352: 7346: 7332: 7326: 7309: 7294: 7293:two-body problem 7288: 7282: 7276: 7270: 7264: 7258: 7252: 7251:elliptical orbit 7243: 7228: 7221:autumnal equinox 7209: 7203: 7196: 7177: 7160: 7142: 7136: 7130: 7110: 7090: 7084: 7078: 7062: 7056: 7050: 7044: 7038: 7037:planetary system 7024: 6998: 6984: 6978: 6964: 6963:constantly faces 6958: 6952: 6946: 6939: 6921: 6907: 6901: 6883: 6877: 6871: 6855: 6854:orbital elements 6849: 6843: 6837: 6831: 6805: 6804:elliptical orbit 6799: 6793: 6787: 6767: 6751: 6745: 6739: 6734: 6732: 6726: 6724: 6717: 6711: 6680: 6655: 6629: 6623: 6589: 6583: 6576: 6557:Lagrangian point 6539: 6533: 6527: 6521: 6515: 6509: 6503: 6497: 6491: 6485: 6478: 6460: 6454: 6436: 6429: 6395: 6389: 6383: 6361: 6338: 6332: 6326: 6306: 6300: 6296:orbit about its 6294: 6288: 6282: 6276: 6258:irregular galaxy 6242: 6236:angular momentum 6232: 6231:planetary system 6226: 6219: 6204:invariable plane 6197: 6191: 6167: 6161: 6126: 6120: 6116:The subfield of 6100: 6099:superior planets 6090: 6081: 6056: 6039: 6025: 5995: 5968: 5962: 5952: 5946: 5932: 5926: 5920: 5902: 5876: 5870: 5864: 5858: 5838: 5832: 5826: 5816: 5810: 5804: 5798: 5797:celestial sphere 5792: 5791:celestial object 5776: 5756: 5750: 5744: 5737: 5719: 5713: 5707: 5701: 5695: 5689: 5683: 5677: 5671: 5665: 5659: 5653: 5637: 5631: 5625: 5619: 5594: 5588: 5587:geometric center 5568: 5562:geometric center 5550: 5544: 5522: 5499: 5493: 5487: 5481: 5467: 5446: 5428: 5427:galactic cluster 5403: 5397: 5391: 5385: 5379: 5370:globular cluster 5363: 5357: 5351: 5335: 5329: 5323: 5317: 5311: 5305: 5288: 5282:Earth's rotation 5278: 5272: 5266: 5261: 5254: 5232: 5226: 5220: 5214: 5192: 5183:geometric albedo 5176: 5170: 5164: 5163:celestial sphere 5146: 5145:geometric center 5126:geometric center 5112: 5090: 5074: 5068: 5062: 5056: 5031: 5025: 5021:The subfield of 4985: 4969: 4963: 4957: 4956:Milky Way Galaxy 4951: 4944: 4926: 4920: 4914: 4908: 4902: 4886: 4880: 4874: 4868: 4862: 4856: 4850: 4844: 4838: 4837:interstellar gas 4832: 4831:stellar remnants 4826: 4810: 4804: 4800:) away from the 4794: 4790:is about 27,000 4788: 4782: 4778:of a particular 4776: 4762: 4756: 4746: 4730: 4724: 4718: 4712: 4706: 4700: 4693: 4671: 4665: 4659: 4653: 4647: 4640: 4625:galactic nucleus 4589: 4583: 4577: 4571: 4566: 4560: 4541: 4535: 4534:celestial sphere 4529: 4528:Milky Way Galaxy 4523: 4507: 4501: 4496: 4473: 4457: 4435: 4419: 4418:deep-sky objects 4413: 4407: 4401: 4395: 4389: 4383: 4376: 4373:background stars 4358: 4352: 4346: 4337: 4331: 4325: 4324:celestial sphere 4319: 4303: 4297: 4291: 4285: 4276: 4270: 4264: 4263:celestial sphere 4258: 4251: 4218: 4212: 4196: 4186: 4172: 4156: 4150: 4144: 4134: 4128: 4104: 4089: 4083: 4076: 4058: 4052: 4046: 4040: 4024: 4018: 4013: 3989: 3959: 3945: 3939: 3933: 3929:that a solitary 3927: 3911: 3881: 3874: 3868: 3862: 3856: 3855:autumnal equinox 3850: 3844: 3838: 3832: 3826: 3820: 3804: 3790: 3784: 3778: 3772: 3771:celestial sphere 3766: 3756: 3740: 3730: 3729:axis of rotation 3720: 3703: 3697: 3691: 3690:orbital elements 3685: 3669: 3663: 3657: 3641: 3635: 3613: 3612:elliptical orbit 3595: 3589: 3583: 3577: 3570: 3559:elliptical orbit 3552: 3546: 3536: 3502: 3496: 3490: 3484: 3478: 3472: 3464:or the Earth, a 3462: 3456: 3450: 3433: 3426: 3420: 3414: 3413:celestial sphere 3407: 3393: 3387: 3381: 3375: 3369: 3363: 3362:celestial sphere 3357: 3342: 3319: 3301: 3278: 3272: 3266: 3260: 3259:stellar remnants 3243: 3237: 3231: 3225: 3200: 3193: 3173: 3167: 3161: 3155: 3149: 3143: 3126: 3109: 3103: 3097: 3087: 3081: 3075: 3069: 3062: 3039: 3032: 3026: 3020: 3013: 2995: 2989: 2983: 2977: 2957: 2951: 2945: 2939: 2933: 2927: 2921: 2915: 2894: 2888: 2871: 2864: 2854: 2832: 2814: 2808: 2777: 2767: 2766:celestial sphere 2761: 2755: 2749: 2743: 2737: 2731: 2725: 2719: 2712: 2709:meridian transit 2693: 2686: 2671: 2648: 2624: 2608: 2602: 2578: 2559: 2555:which exists in 2549: 2522: 2521:solar prominence 2516: 2510: 2504: 2474: 2468: 2447: 2440: 2430: 2429:celestial sphere 2426:A region on the 2414: 2408: 2398: 2381: 2364: 2363:stellar remnants 2358: 2352: 2346: 2340: 2333: 2311: 2305: 2272: 2263:commensurability 2244: 2194: 2177: 2147:equivalent width 2144: 2135: 2124: 2097: 2091: 2085: 2068: 2062: 2056: 2050: 2044: 2038: 2032: 2026: 2020: 2014: 1998: 1992: 1991:background stars 1986: 1977:celestial sphere 1970: 1964: 1958: 1957:celestial sphere 1952: 1951:axis of rotation 1946: 1929: 1912: 1906: 1900: 1894: 1888: 1884:of all types of 1878: 1861: 1855: 1849: 1842: 1835: 1834:axis of rotation 1822: 1816: 1810: 1804: 1798: 1797:celestial sphere 1728: 1722: 1708: 1683: 1675: 1650: 1630: 1624: 1618: 1612: 1596: 1590: 1560: 1554: 1548: 1547:planetary system 1538: 1537:elliptical orbit 1528: 1507: 1500: 1455:axis of rotation 1448: 1438: 1432: 1426: 1419: 1401: 1395: 1385: 1379:equatorial bulge 1375: 1369: 1363: 1359:with respect to 1353: 1352:axis of rotation 1347: 1341: 1332:axial precession 1314: 1292: 1266:astrophotography 1259: 1253: 1239:10 light-years). 1238: 1234: 1221: 1204: 1190: 1184: 1178: 1173: 1167: 1161: 1155: 1149: 1133: 1127: 1121: 1115: 1114:planetary system 1109: 1103: 1096: 1093:celestial object 1077: 1059: 1053: 1047: 1041: 1035: 1029: 1022: 1004: 1003:celestial bodies 998: 981: 974: 968: 950: 931: 906: 888: 881: 855: 849: 843: 829: 823: 807: 801: 795: 789: 783: 777: 767: 761: 755: 739: 733: 727: 711: 705: 699: 684: 677: 671: 665: 659: 653: 646: 627: 620: 614: 598: 597:orbital elements 592: 586: 580: 573: 551: 545: 539: 533: 527: 521: 490: 471: 464: 458: 441: 434: 417: 410: 393: 386: 366: 344: 323: 313: 307: 283: 273: 267: 250: 244: 238: 222: 216: 210: 204: 188: 182: 176: 21: 17111: 17110: 17106: 17105: 17104: 17102: 17101: 17100: 17076: 17075: 17074: 17069: 16968:Hebrew toponyms 16963:Arabic toponyms 16801: 16791: 16761: 16756: 16744: 16732: 16724: 16717: 16708: 16701: 16696:X-ray telescope 16694: 16687: 16678: 16671: 16664: 16657: 16650: 16643: 16636: 16629: 16622: 16615: 16606: 16599: 16592: 16585: 16576: 16569: 16562: 16555: 16548: 16541: 16534: 16527: 16516: 16509: 16502: 16495: 16488: 16481: 16474: 16467: 16460: 16453: 16446: 16439: 16431: 16420: 16413: 16404: 16397: 16390: 16383: 16376: 16369: 16362: 16355: 16348: 16341: 16334: 16327: 16320: 16307: 16302:Multi-messenger 16300: 16293: 16286: 16279: 16272: 16265: 16258: 16247: 16240: 16231: 16224: 16217: 16210: 16207: 16198: 16193: 16186: 16179: 16168: 16159: 16152: 16141: 16130: 16125:Space telescope 16123: 16116: 16109: 16102: 16084: 16077: 16070: 16063: 16056: 16049: 16040: 16033: 16026: 16018: 16013: 15977: 15975: 15966: 15959: 15957: 15948: 15941: 15939: 15936:Public Outreach 15930: 15923: 15921: 15917:Astronomy Terms 15914: 15907: 15905: 15896: 15893: 15888: 15887: 15880: 15864: 15860: 15811: 15807: 15768:(3): 997–1007, 15758: 15754: 15747: 15739:, p. 257, 15727: 15723: 15674: 15670: 15663: 15647: 15643: 15636: 15628:, p. 248, 15616: 15612: 15604: 15602: 15589: 15588: 15584: 15578: 15562: 15558: 15551: 15535: 15531: 15522: 15520: 15513: 15512: 15508: 15499: 15497: 15490: 15489: 15485: 15478: 15462: 15458: 15434: 15430: 15423: 15407: 15403: 15362: 15358: 15335: 15331: 15324: 15308: 15304: 15297: 15281: 15277: 15271: 15253: 15249: 15238: 15234: 15215: 15211: 15172: 15168: 15159: 15157: 15146: 15142: 15133: 15131: 15122:Esken, Thomas, 15120: 15116: 15110: 15094: 15090: 15067: 15063: 15049: 15033: 15024: 15005: 15001: 14950: 14946: 14905: 14901: 14878: 14874: 14866: 14864: 14851: 14850: 14817: 14809: 14807: 14798: 14797: 14793: 14784: 14782: 14780: 14772:, p. 163, 14760: 14756: 14747: 14745: 14743: 14735:, p. 110, 14723: 14719: 14706: 14705: 14701: 14660: 14656: 14650: 14636: 14632: 14581: 14577: 14570: 14554: 14550: 14516: 14510: 14506: 14475: 14471: 14464: 14448: 14444: 14437: 14417: 14413: 14407: 14391: 14380: 14375: 14343: 14333: 14283: 14253: 14236: 14229: 14203: 14168: 14163: 14153:late-type stars 14137: 14109:stellar remnant 14103: 14083: 14078: 14052: 14021: 14007:radial velocity 13994: 13987: 13912: 13890: 13883: 13874: 13845: 13805: 13761: 13757: 13753: 13749: 13739: 13730: 13667: 13658: 13632: 13622: 13557: 13553: 13539:of an orbiting 13530: 13504: 13462: 13453: 13416: 13382: 13373: 13362: 13334: 13294: 13266: 13259: 13227: 13222: 13212: 13199:in the Earth's 13178: 13128: 13066:rotation period 13045: 13005: 12993: 12991: 12961: 12958:surface gravity 12920: 12898:mass of the Sun 12886: 12874:inferior planet 12844: 12842:superior planet 12835: 12826: 12773: 12751: 12725: 12716: 12714:stellar remnant 12707: 12671: 12640: 12633: 12617:common envelope 12602: 12593: 12584: 12541: 12516: 12494: 12456: 12437: 12376: 12367: 12349: 12297: 12285: 12283: 12282:(approximately 12277: 12275: 12268:Earth's gravity 12250: 12247: 12241: 12238: 12232: 12222: 12181: 12172: 12146: 12136:radial velocity 12110: 12092: 12082:winter solstice 12075:summer solstice 12045: 12006:alpha particles 11993: 11971:mean solar time 11944:in the Earth's 11929: 11898:, and numerous 11880:of the Earth's 11871: 11853: 11821: 11819: 11816: 11779: 11758: 11755: 11753: 11743: 11741: 11738: 11726: 11717: 11683: 11645:by the Earth's 11630: 11569:rotation period 11557: 11548: 11503: 11494: 11469:in the Earth's 11454: 11420: 11418:sidereal period 11380:rotation period 11374: 11323: 11289:major semi-axis 11283: 11281:semi-major axis 11273: 11257: 11235: 11225: 11182: 11173: 11143: 11127: 11122: 11092: 11060: 11058:rotation period 11026: 10998:galactic center 10983:starless planet 10965: 10939: 10922:Rings of Saturn 10896:that orbits an 10881: 10855: 10853:right ascension 10828:prograde motion 10805: 10794: 10785: 10775:irregular moons 10735: 10726: 10691: 10681:radio astronomy 10665: 10631: 10629:radio astronomy 10607: 10605:radial velocity 10600: 10538: 10505:superior planet 10481: 10467:of a series of 10456: 10451: 10429: 10416:synchronization 10412:eccentric orbit 10407: 10395: 10386: 10352: 10342: 10312: 10271: 10269:prograde motion 10238: 10229: 10195: 10163: 10141: 10097: 10075: 9999:gravitationally 9994: 9957: 9932:emission nebula 9927: 9917: 9858: 9842: 9795: 9779: 9728:reference plane 9722: 9713: 9704: 9664: 9625: 9601: 9571: 9538: 9520: 9513: 9469: 9439: 9424:minimal gravity 9400: 9368: 9359: 9323: 9307: 9271:orbital periods 9255:semi-major axis 9231: 9184:defined by the 9182:geometric plane 9177: 9167:sidereal period 9134: 9118:descending node 9103:to which it is 9082: 9073: 9045: 9034:reference plane 9001: 8979: 8944: 8900:gravitationally 8895: 8884: 8874:molecular cloud 8868: 8854: 8813:Öpik–Oort cloud 8807: 8773: 8739: 8730: 8669: 8667:observation arc 8651: 8629: 8603: 8598: 8570: 8560: 8550: 8505: 8445: 8436: 8405: 8394: 8336: 8286: 8236: 8212: 8184: 8159:active galaxies 8154: 8149: 8140: 8092: 8076:molecular cloud 8055: 8024: 8006: 7988: 7925: 7875: 7857: 7838: 7818: 7816:molecular cloud 7780: 7740: 7729:semi-minor axis 7722: 7672:Galactic Center 7630: 7602: 7582: 7552: 7534: 7500: 7478: 7462: 7405: 7390:Charles Messier 7373: 7339: 7319: 7301: 7245: 7239: 7187: 7176:semi-major axis 7169: 7148:and undergoing 7123: 7099: 7071: 7017: 7009: 6930: 6914: 6864: 6824: 6814: 6780: 6779:line of apsides 6760: 6730: 6728: 6722: 6720: 6704: 6673: 6664: 6638: 6617: 6610: 6569:libration point 6559: 6552: 6469: 6426:Keplerian orbit 6420: 6411: 6404: 6371: 6354: 6347: 6322:A curve on the 6319: 6269: 6260: 6251: 6206: 6184: 6150: 6140: 6113: 6066: 6064:inferior planet 6048: 5988: 5981: 5961:galactic corona 5939: 5925:mass of the Sun 5913: 5888:pulsating stars 5883: 5882:hybrid pulsator 5866:. Similar to a 5857:celestial poles 5847: 5837:right ascension 5825:rotational axis 5785: 5765: 5728: 5646: 5612: 5603: 5590:of the Earth's 5581: 5564:of the Earth's 5557: 5543:spiral galaxies 5515: 5508: 5460: 5421: 5412: 5372: 5344: 5328:semi-major axis 5298: 5241: 5207: 5185: 5157: 5139: 5130:oblate spheroid 5121: 5083: 5045: 5042:gamma-ray burst 5018: 4993:Galileo Galilei 4978: 4962:galaxy clusters 4935: 4895: 4819: 4803:Galactic Center 4769: 4739: 4717:galactic center 4680: 4678:galactic period 4637:galactic center 4627: 4618: 4616:galactic corona 4609: 4556:The rotational 4553: 4551:Galactic Center 4516: 4489: 4482: 4466: 4428: 4403:other than the 4367: 4312: 4242: 4227: 4205: 4179: 4165: 4121: 4114: 4096: 4067: 4033: 4006: 3970: 3923:A curve on the 3920: 3891: 3889:escape velocity 3813: 3797: 3749: 3713: 3678: 3650: 3624: 3588:circular orbits 3561: 3529: 3511: 3443: 3389:because of the 3368:reference plane 3349:defined by the 3329: 3311: 3300:late-type stars 3294: 3292:early-type star 3287: 3233:stars like the 3218: 3209: 3186: 3169:in the Earth's 3166:celestial poles 3157:, or a distant 3136: 3125:prograde motion 3118: 3049: 3047:detached object 3004: 3002:descending node 2966: 2964:degenerate star 2908: 2905:deep-sky object 2893:Keplerian orbit 2881: 2870:right ascension 2847: 2818:infrared excess 2801: 2794: 2703: 2662: 2655: 2637: 2617: 2587: 2569: 2540: 2531: 2493: 2483: 2457: 2423: 2407:right ascension 2391: 2373: 2324: 2310:radial velocity 2294: 2271:orbital periods 2265: 2237: 2219: 2210: 2201: 2185: 2175: 2169: 2142: 2137: 2133: 2127: 2113: 2106: 2078: 2046:. Centaurs are 2043:Jupiter trojans 2040:but beyond the 2025:semi-major axis 2007: 1979: 1939: 1921: 1914:, among others. 1871: 1787: 1765: 1757: 1755:Calibrator star 1750: 1741: 1701: 1666: 1659: 1643: 1605: 1586:The prevailing 1583: 1569: 1517: 1488: 1466: 1457: 1410: 1377:on the Earth's 1334: 1323: 1277: 1268: 1246: 1236: 1232: 1214: 1142: 1087: 1068: 1013: 991: 961: 941: 923: 872: 816: 748: 723:Any pattern of 720: 692: 683:descending node 637: 607: 560: 514: 504: 481: 451: 427: 403: 375: 359: 303:received by an 301:solar radiation 296: 260: 231: 218:, or 32.6 200:A measure of a 197: 169: 162: 157: 156: 57: 28: 23: 22: 15: 12: 11: 5: 17109: 17099: 17098: 17093: 17088: 17071: 17070: 17068: 17067: 17062: 17057: 17052: 17047: 17042: 17037: 17032: 17027: 17022: 17020:Nanotechnology 17017: 17012: 17007: 17002: 16997: 16992: 16990:Machine vision 16987: 16982: 16977: 16976: 16975: 16970: 16965: 16960: 16955: 16947: 16946: 16945: 16940: 16932: 16927: 16922: 16917: 16916: 16915: 16910: 16902: 16897: 16892: 16887: 16882: 16877: 16872: 16867: 16862: 16857: 16852: 16847: 16842: 16837: 16832: 16827: 16822: 16817: 16812: 16806: 16803: 16802: 16793:Glossaries of 16790: 16789: 16782: 16775: 16767: 16758: 16757: 16755: 16754: 16742: 16729: 16726: 16725: 16723: 16722: 16715: 16714: 16713: 16706: 16699: 16685: 16684: 16683: 16676: 16669: 16662: 16648: 16641: 16634: 16627: 16620: 16613: 16612: 16611: 16597: 16590: 16583: 16574: 16567: 16560: 16553: 16546: 16543:Astrochemistry 16539: 16532: 16524: 16522: 16518: 16517: 16515: 16514: 16507: 16500: 16493: 16486: 16479: 16476:Hale Telescope 16472: 16465: 16458: 16451: 16444: 16436: 16434: 16426: 16425: 16422: 16421: 16419: 16418: 16411: 16410: 16409: 16395: 16388: 16381: 16374: 16367: 16360: 16353: 16346: 16339: 16332: 16325: 16317: 16315: 16309: 16308: 16306: 16305: 16298: 16291: 16284: 16277: 16270: 16263: 16255: 16253: 16249: 16248: 16246: 16245: 16238: 16237: 16236: 16222: 16215: 16209:Visible-light 16205: 16191: 16184: 16176: 16174: 16170: 16169: 16167: 16166: 16165: 16164: 16150: 16138: 16136: 16132: 16131: 16129: 16128: 16121: 16114: 16107: 16099: 16097: 16090: 16086: 16085: 16083: 16082: 16075: 16068: 16061: 16054: 16047: 16046: 16045: 16031: 16023: 16020: 16019: 16012: 16011: 16004: 15997: 15989: 15983: 15982: 15964: 15946: 15928: 15912: 15892: 15891:External links 15889: 15886: 15885: 15878: 15858: 15845:10.1086/422802 15821:(2): 724–728, 15805: 15752: 15745: 15721: 15668: 15662:978-3319187723 15661: 15641: 15635:978-3527408962 15634: 15610: 15582: 15577:978-3863950927 15576: 15556: 15549: 15529: 15506: 15483: 15477:978-0192542618 15476: 15456: 15428: 15422:978-1139425421 15421: 15401: 15356: 15329: 15323:978-1107534209 15322: 15302: 15295: 15275: 15269: 15247: 15232: 15209: 15196:10.1086/130908 15166: 15154:TAWARIKHKHWANI 15140: 15114: 15109:978-1785461477 15108: 15088: 15061: 15047: 15022: 14999: 14944: 14899: 14872: 14815: 14804:Universe Today 14791: 14779:978-0199609055 14778: 14754: 14741: 14717: 14699: 14670:(1): 228–250, 14654: 14649:978-1438109329 14648: 14630: 14591:(1): 189–195, 14575: 14569:978-0521514897 14568: 14548: 14504: 14499:10.1086/161945 14469: 14462: 14442: 14436:978-3540769491 14435: 14411: 14405: 14377: 14376: 14374: 14371: 14370: 14369: 14364: 14359: 14354: 14349: 14342: 14339: 14338: 14337: 14334: 14331:zodiacal light 14329: 14327: 14284: 14279: 14277: 14274:nuclear fusion 14254: 14248: 14246: 14237: 14232: 14228: 14225: 14224: 14223: 14204: 14199: 14197: 14194:X-ray emission 14172:An acronym of 14169: 14166: 14162: 14159: 14158: 14157: 14138: 14133: 14131: 14118:nuclear fusion 14104: 14099: 14097: 14088:spectral lines 14084: 14082:weak-line star 14081: 14077: 14074: 14073: 14072: 14053: 14047: 14045: 14042:virial theorem 14022: 14017: 14015: 14012:spectral lines 13995: 13990: 13986: 13983: 13982: 13981: 13968: 13913: 13908: 13906: 13896:Johnson system 13891: 13886: 13882: 13879: 13878: 13877: 13875: 13870: 13868: 13846: 13841: 13839: 13806: 13801: 13799: 13762: 13744: 13742: 13740: 13735: 13733: 13731: 13726: 13724: 13703:transit method 13683: 13668: 13663: 13661: 13659: 13653: 13635: 13633: 13628: 13626: 13623: 13620: 13618: 13602:semimajor axis 13558: 13548: 13546: 13531: 13528: 13526: 13505: 13502: 13500: 13463: 13458: 13456: 13454: 13449: 13447: 13417: 13412: 13410: 13394:galactic plane 13383: 13378: 13376: 13374: 13369: 13367: 13363: 13358: 13356: 13335: 13330: 13328: 13295: 13290: 13288: 13267: 13264: 13262: 13260: 13255: 13253: 13228: 13225: 13221: 13218: 13217: 13216: 13213: 13208: 13206: 13179: 13174: 13172: 13158:orbital period 13129: 13126:synodic period 13124: 13122: 13100:orbital period 13046: 13041: 13039: 13035:same direction 13023:orbital period 13006: 13001: 12999: 12962: 12956: 12954: 12921: 12916: 12914: 12887: 12881: 12879: 12845: 12840: 12838: 12836: 12831: 12829: 12827: 12822: 12820: 12774: 12769: 12767: 12752: 12747: 12745: 12726: 12721: 12719: 12717: 12712: 12710: 12708: 12703: 12701: 12676:magnetic field 12672: 12667: 12665: 12641: 12638: 12636: 12634: 12629: 12627: 12612: 12603: 12598: 12596: 12594: 12589: 12587: 12585: 12580: 12578: 12542: 12537: 12535: 12517: 12512: 12510: 12495: 12492: 12490: 12457: 12454: 12452: 12438: 12433: 12431: 12382:stellar system 12377: 12372: 12370: 12368: 12363: 12361: 12350: 12347:star catalogue 12345: 12343: 12298: 12293: 12291: 12251: 12245: 12236: 12227: 12225: 12223: 12218: 12216: 12182: 12177: 12175: 12173: 12170:speed of light 12168: 12149: 12147: 12142: 12140: 12131:Doppler effect 12111: 12106: 12104: 12093: 12088: 12086: 12046: 12041: 12039: 11994: 11989: 11987: 11983:ephemeris time 11935:diurnal motion 11930: 11925: 11923: 11872: 11867: 11865: 11854: 11849: 11847: 11822: 11817: 11814: 11809: 11807: 11780: 11775: 11773: 11744: 11739: 11736: 11731: 11729: 11727: 11722: 11720: 11718: 11713: 11711: 11694:solar granules 11684: 11679: 11677: 11631: 11626: 11624: 11558: 11553: 11551: 11549: 11543: 11541: 11504: 11499: 11497: 11495: 11490: 11488: 11460:diurnal motion 11455: 11450: 11448: 11426:orbital period 11421: 11416: 11414: 11375: 11370: 11368: 11357:vernal equinox 11324: 11319: 11317: 11284: 11279: 11277: 11274: 11269: 11267: 11258: 11255: 11253: 11236: 11233:secular motion 11231: 11229: 11226: 11223: 11221: 11183: 11178: 11176: 11174: 11171:scattered disc 11169: 11167: 11144: 11139: 11137: 11128: 11125: 11121: 11118: 11117: 11116: 11093: 11090: 11088: 11061: 11056: 11054: 11027: 11022: 11020: 10995:that orbits a 10966: 10961: 10959: 10940: 10935: 10933: 10920:, as with the 10882: 10877: 10875: 10856: 10851: 10833: 10806: 10801: 10799: 10795: 10790: 10788: 10786: 10781: 10779: 10736: 10731: 10729: 10727: 10722: 10720: 10700:for a typical 10692: 10687: 10685: 10666: 10661: 10659: 10652:radio antennas 10650:, using large 10632: 10627: 10625: 10608: 10603: 10599: 10596: 10595: 10594: 10591:emission lines 10567:of gas onto a 10539: 10534: 10515: 10482: 10477: 10475: 10457: 10454: 10450: 10447: 10446: 10445: 10430: 10425: 10423: 10408: 10405: 10403: 10396: 10391: 10389: 10387: 10382: 10380: 10353: 10348: 10346: 10343: 10338: 10336: 10313: 10310: 10308: 10272: 10267: 10265: 10239: 10234: 10232: 10230: 10225: 10223: 10196: 10191: 10189: 10164: 10159: 10157: 10142: 10137: 10135: 10098: 10093: 10091: 10085:planetary body 10076: 10070: 10068: 9995: 9990: 9988: 9958: 9953: 9951: 9928: 9923: 9921: 9918: 9913: 9911: 9873:secondary body 9859: 9856:planetary body 9854: 9852: 9843: 9840: 9838: 9796: 9791: 9789: 9780: 9777: 9775: 9759:ecliptic plane 9723: 9718: 9716: 9714: 9709: 9707: 9705: 9700: 9698: 9665: 9660: 9658: 9626: 9621: 9619: 9602: 9597: 9595: 9572: 9567: 9565: 9539: 9534: 9532: 9521: 9519:peak magnitude 9518: 9516: 9514: 9509: 9507: 9470: 9464: 9438: 9435: 9434: 9433: 9401: 9396: 9394: 9369: 9364: 9362: 9360: 9357: 9355: 9345:orbital period 9324: 9319: 9300: 9232: 9227: 9225: 9180:The imaginary 9178: 9173: 9171: 9135: 9132:orbital period 9130: 9128: 9112:ascending node 9083: 9078: 9076: 9074: 9069: 9067: 9046: 9041: 9011: 9002: 8997: 8995: 8980: 8975: 8973: 8945: 8942: 8940: 8935:center of mass 8896: 8891: 8889: 8885: 8880: 8878: 8869: 8864: 8862: 8855: 8850: 8848: 8808: 8803: 8801: 8774: 8769: 8767: 8740: 8735: 8733: 8731: 8726: 8724: 8670: 8665: 8663: 8652: 8647: 8645: 8630: 8627:OB association 8625: 8623: 8604: 8601: 8597: 8594: 8593: 8592: 8571: 8566: 8564: 8561: 8558:number density 8556: 8554: 8551: 8545: 8543: 8506: 8501: 8499: 8446: 8441: 8439: 8437: 8431: 8429: 8406: 8401: 8399: 8395: 8390: 8388: 8337: 8332: 8330: 8287: 8281: 8279: 8237: 8232: 8230: 8213: 8208: 8206: 8185: 8180: 8178: 8175:emission lines 8155: 8152: 8148: 8145: 8144: 8143: 8141: 8136: 8134: 8093: 8088: 8086: 8056: 8051: 8049: 8045:celestial body 8025: 8020: 8018: 8007: 8002: 8000: 7989: 7984: 7982: 7926: 7921: 7919: 7876: 7871: 7869: 7858: 7853: 7851: 7839: 7834: 7832: 7819: 7814: 7812: 7789:that orbits a 7781: 7776: 7774: 7741: 7736: 7734: 7723: 7718: 7685: 7682: 7631: 7626: 7624: 7603: 7600: 7598: 7594:micrometeorite 7583: 7580:micrometeoroid 7578: 7576: 7553: 7550:micrometeorite 7548: 7546: 7535: 7530: 7528: 7501: 7496: 7494: 7479: 7474: 7472: 7463: 7458: 7456: 7430:micrometeoroid 7406: 7401: 7399: 7374: 7371:Messier object 7369: 7367: 7340: 7337: 7335: 7320: 7315: 7313: 7302: 7299: 7297: 7281:orbital period 7275:circular orbit 7246: 7234: 7232: 7217:vernal equinox 7188: 7183: 7181: 7170: 7165: 7163: 7150:nuclear fusion 7126:A category of 7124: 7119: 7117: 7100: 7095: 7093: 7072: 7067: 7065: 7018: 7012: 7008: 7005: 7004: 6987: 6931: 6926: 6924: 6915: 6912: 6910: 6893:per second or 6865: 6860: 6858: 6842:ascending node 6825: 6819: 6817: 6815: 6810: 6808: 6781: 6778: 6776: 6761: 6758:limb darkening 6756: 6754: 6710:speed of light 6705: 6699: 6697: 6674: 6669: 6667: 6665: 6662:late-type star 6660: 6658: 6639: 6634: 6632: 6615: 6608: 6565:Lagrange point 6560: 6555: 6551: 6548: 6547: 6546: 6470: 6465: 6463: 6421: 6416: 6414: 6412: 6407: 6403: 6400: 6399: 6398: 6372: 6366: 6364: 6355: 6350: 6346: 6343: 6342: 6341: 6320: 6315: 6313: 6270: 6267:irregular moon 6265: 6263: 6261: 6256: 6254: 6252: 6247: 6245: 6207: 6202: 6200: 6185: 6180: 6178: 6151: 6145: 6143: 6141: 6135: 6133: 6128:detectable at 6114: 6109: 6107: 6067: 6062: 6060: 6049: 6044: 6042: 5989: 5984: 5980: 5977: 5976: 5975: 5940: 5937: 5935: 5914: 5911: 5909: 5884: 5881: 5879: 5850:Any imaginary 5848: 5843: 5841: 5786: 5781: 5779: 5766: 5761: 5759: 5729: 5724: 5722: 5647: 5642: 5640: 5613: 5608: 5606: 5604: 5599: 5597: 5582: 5577: 5575: 5558: 5555: 5553: 5516: 5511: 5507: 5504: 5503: 5502: 5461: 5456: 5435: 5422: 5417: 5415: 5413: 5408: 5406: 5373: 5368: 5366: 5345: 5340: 5338: 5310:orbital period 5299: 5293: 5291: 5277:same direction 5242: 5237: 5235: 5208: 5205: 5203: 5186: 5181: 5179: 5158: 5155: 5153: 5140: 5135: 5133: 5122: 5117: 5115: 5084: 5079: 5077: 5046: 5040: 5038: 5033:detectable at 5019: 5014: 5012: 4991:discovered by 4979: 4976:Galilean moons 4974: 4972: 4936: 4931: 4929: 4896: 4893:galaxy cluster 4891: 4889: 4855:center of mass 4820: 4815: 4813: 4770: 4767: 4765: 4740: 4735: 4733: 4681: 4676: 4674: 4628: 4623: 4621: 4619: 4614: 4612: 4610: 4605: 4603: 4588:constellations 4554: 4549: 4547: 4517: 4512: 4510: 4490: 4485: 4481: 4478: 4477: 4476: 4467: 4462: 4460: 4429: 4424: 4422: 4368: 4363: 4361: 4313: 4308: 4306: 4243: 4237: 4235: 4228: 4223: 4221: 4206: 4201: 4199: 4180: 4177: 4175: 4166: 4161: 4159: 4122: 4117: 4113: 4110: 4109: 4108: 4097: 4094: 4092: 4068: 4063: 4061: 4034: 4029: 4027: 4007: 4002: 4000: 3971: 3966: 3948: 3921: 3916: 3914: 3913:of any radius. 3905:center of mass 3897:kinetic energy 3892: 3887: 3885: 3873:directly above 3849:vernal equinox 3814: 3809: 3807: 3798: 3795: 3793: 3789:vernal equinox 3750: 3745: 3743: 3714: 3709: 3707: 3679: 3674: 3672: 3651: 3646: 3644: 3625: 3620: 3602: 3567:elliptic orbit 3562: 3557: 3555: 3530: 3525: 3523: 3512: 3507: 3505: 3483:vernal equinox 3444: 3439: 3396: 3335:ecliptic plane 3330: 3325: 3323: 3312: 3307: 3305: 3295: 3290: 3286: 3283: 3282: 3281: 3219: 3214: 3212: 3210: 3205: 3203: 3187: 3182: 3180: 3177:diurnal circle 3137: 3134:diurnal motion 3132: 3130: 3119: 3114: 3112: 3108:scattered disc 3050: 3045: 3043: 3038:ascending node 3005: 3000: 2998: 2967: 2962: 2960: 2909: 2903: 2901: 2882: 2879:decretion disk 2877: 2875: 2848: 2843: 2827:Circumstellar 2821: 2804:A ring-shaped 2802: 2797: 2793: 2790: 2789: 2788: 2760:appear to move 2704: 2699: 2697: 2663: 2660: 2658: 2656: 2653: 2651: 2638: 2633: 2631: 2618: 2613: 2611: 2588: 2583: 2581: 2570: 2564: 2562: 2541: 2536: 2534: 2532: 2527: 2525: 2494: 2488: 2486: 2484: 2479: 2477: 2458: 2453: 2451: 2424: 2419: 2417: 2392: 2387: 2385: 2374: 2369: 2367: 2330:compact object 2325: 2320: 2318: 2295: 2292: 2290: 2266: 2261: 2259: 2238: 2233: 2231: 2220: 2215: 2213: 2211: 2206: 2204: 2202: 2199: 2197: 2186: 2181: 2179: 2173: 2161:light, to the 2151:singly ionized 2140: 2131: 2114: 2111: 2109: 2107: 2102: 2100: 2079: 2073: 2071: 2016:with either a 2008: 2003: 2001: 1980: 1975: 1973: 1940: 1937:celestial pole 1935: 1933: 1922: 1917: 1915: 1874:The branch of 1872: 1867: 1825: 1790:The imaginary 1788: 1783: 1781: 1772:placed at the 1766: 1763: 1761: 1758: 1753: 1749: 1746: 1745: 1744: 1742: 1737: 1735: 1712:nuclear fusion 1702: 1697: 1695: 1667: 1664: 1662: 1660: 1655: 1653: 1644: 1639: 1637: 1606: 1601: 1599: 1584: 1579: 1577: 1570: 1565: 1563: 1522:center of mass 1518: 1513: 1487: 1484: 1483: 1482: 1467: 1462: 1460: 1458: 1453: 1451: 1437:orbital period 1411: 1406: 1404: 1335: 1330: 1328: 1324: 1319: 1317: 1278: 1273: 1271: 1269: 1264: 1262: 1247: 1242: 1240: 1225:semimajor axis 1215: 1209: 1207: 1177:constellations 1143: 1138: 1136: 1088: 1083: 1081: 1069: 1064: 1062: 1019:celestial body 1014: 1009: 1007: 992: 987: 985: 962: 957: 955: 942: 937: 935: 924: 919: 917: 898:on Earth, the 873: 868: 866: 817: 812: 810: 749: 744: 742: 721: 716: 714: 693: 690: 688: 638: 635:ascending node 633: 631: 608: 603: 601: 585:ascending node 561: 556: 554: 526:planetary body 515: 510: 508: 505: 500: 498: 482: 477: 475: 452: 447: 445: 428: 423: 421: 404: 399: 397: 376: 371: 369: 360: 357:albedo feature 355: 343:albedo feature 330: 297: 292: 290: 261: 255: 253: 232: 229:accretion disk 227: 225: 198: 193: 191: 170: 165: 161: 158: 155: 154: 152:External links 149: 144: 139: 58: 56: 53: 26: 9: 6: 4: 3: 2: 17108: 17097: 17094: 17092: 17089: 17087: 17084: 17083: 17081: 17066: 17063: 17061: 17058: 17056: 17053: 17051: 17048: 17046: 17043: 17041: 17038: 17036: 17033: 17031: 17028: 17026: 17023: 17021: 17018: 17016: 17013: 17011: 17008: 17006: 17003: 17001: 16998: 16996: 16993: 16991: 16988: 16986: 16983: 16981: 16978: 16974: 16971: 16969: 16966: 16964: 16961: 16959: 16956: 16954: 16951: 16950: 16948: 16944: 16941: 16939: 16936: 16935: 16933: 16931: 16928: 16926: 16923: 16921: 16918: 16914: 16911: 16909: 16906: 16905: 16903: 16901: 16898: 16896: 16893: 16891: 16888: 16886: 16883: 16881: 16878: 16876: 16873: 16871: 16868: 16866: 16863: 16861: 16858: 16856: 16853: 16851: 16848: 16846: 16843: 16841: 16838: 16836: 16833: 16831: 16828: 16826: 16823: 16821: 16818: 16816: 16813: 16811: 16808: 16807: 16804: 16800: 16796: 16788: 16783: 16781: 16776: 16774: 16769: 16768: 16765: 16752: 16743: 16740: 16731: 16730: 16727: 16720: 16716: 16711: 16707: 16704: 16700: 16697: 16693: 16692: 16690: 16686: 16681: 16677: 16674: 16670: 16667: 16663: 16660: 16656: 16655: 16653: 16649: 16646: 16642: 16639: 16635: 16632: 16628: 16625: 16621: 16618: 16614: 16609: 16605: 16604: 16602: 16601:Constellation 16598: 16595: 16591: 16588: 16584: 16581: 16580: 16575: 16572: 16568: 16565: 16561: 16558: 16554: 16551: 16547: 16544: 16540: 16537: 16533: 16530: 16526: 16525: 16523: 16519: 16512: 16508: 16505: 16501: 16498: 16494: 16491: 16487: 16484: 16480: 16477: 16473: 16470: 16466: 16463: 16459: 16456: 16452: 16449: 16445: 16442: 16438: 16437: 16435: 16433: 16427: 16416: 16412: 16407: 16403: 16402: 16400: 16396: 16393: 16389: 16386: 16382: 16379: 16375: 16372: 16368: 16365: 16361: 16358: 16354: 16351: 16347: 16344: 16340: 16337: 16333: 16330: 16326: 16323: 16319: 16318: 16316: 16314: 16310: 16303: 16299: 16296: 16292: 16289: 16285: 16282: 16278: 16275: 16271: 16268: 16264: 16261: 16257: 16256: 16254: 16252:Other methods 16250: 16243: 16239: 16234: 16230: 16229: 16227: 16223: 16220: 16216: 16213: 16206: 16201: 16196: 16192: 16189: 16188:Submillimetre 16185: 16182: 16178: 16177: 16175: 16171: 16162: 16158: 16157: 16155: 16151: 16148: 16147:Extragalactic 16144: 16140: 16139: 16137: 16133: 16126: 16122: 16119: 16115: 16112: 16111:Observational 16108: 16105: 16101: 16100: 16098: 16094: 16091: 16087: 16080: 16076: 16073: 16069: 16066: 16062: 16059: 16055: 16052: 16048: 16043: 16039: 16038: 16036: 16032: 16029: 16025: 16024: 16021: 16017: 16010: 16005: 16003: 15998: 15996: 15991: 15990: 15987: 15973: 15969: 15965: 15955: 15951: 15947: 15937: 15933: 15929: 15919: 15918: 15913: 15903: 15899: 15895: 15894: 15881: 15875: 15871: 15870: 15862: 15854: 15850: 15846: 15842: 15838: 15834: 15829: 15824: 15820: 15816: 15809: 15801: 15797: 15793: 15789: 15785: 15781: 15776: 15771: 15767: 15763: 15756: 15748: 15746:0-521-38996-8 15742: 15738: 15734: 15733: 15725: 15717: 15713: 15709: 15705: 15701: 15697: 15692: 15687: 15683: 15679: 15672: 15664: 15658: 15654: 15653: 15645: 15637: 15631: 15627: 15623: 15622: 15614: 15601:on 2011-10-24 15600: 15596: 15592: 15586: 15579: 15573: 15569: 15568: 15560: 15552: 15546: 15542: 15541: 15533: 15518: 15517: 15510: 15495: 15494: 15487: 15479: 15473: 15469: 15468: 15460: 15452: 15448: 15444: 15440: 15432: 15424: 15418: 15414: 15413: 15405: 15397: 15393: 15388: 15383: 15379: 15375: 15371: 15367: 15360: 15352: 15348: 15344: 15340: 15333: 15325: 15319: 15315: 15314: 15306: 15298: 15296:9780521529273 15292: 15288: 15287: 15279: 15272: 15266: 15262: 15258: 15251: 15243: 15236: 15228: 15224: 15220: 15213: 15205: 15201: 15197: 15193: 15189: 15185: 15181: 15177: 15170: 15155: 15151: 15144: 15129: 15125: 15118: 15111: 15105: 15101: 15100: 15092: 15084: 15080: 15076: 15072: 15065: 15058: 15054: 15050: 15048:9780199214938 15044: 15040: 15039: 15031: 15029: 15027: 15018: 15014: 15010: 15003: 14995: 14991: 14986: 14981: 14977: 14973: 14968: 14963: 14959: 14955: 14948: 14940: 14936: 14932: 14928: 14923: 14918: 14914: 14910: 14903: 14895: 14891: 14887: 14883: 14876: 14863:on 2022-02-23 14862: 14858: 14854: 14848: 14846: 14844: 14842: 14840: 14838: 14836: 14834: 14832: 14830: 14828: 14826: 14824: 14822: 14820: 14805: 14801: 14795: 14781: 14775: 14771: 14767: 14766: 14758: 14744: 14742:0-470-09220-3 14738: 14734: 14730: 14729: 14721: 14713: 14709: 14703: 14695: 14691: 14686: 14681: 14677: 14673: 14669: 14665: 14658: 14651: 14645: 14641: 14634: 14626: 14622: 14617: 14612: 14608: 14604: 14599: 14594: 14590: 14586: 14579: 14571: 14565: 14561: 14560: 14552: 14543: 14538: 14534: 14530: 14526: 14522: 14515: 14508: 14500: 14496: 14492: 14488: 14484: 14480: 14473: 14465: 14463:9780521339070 14459: 14455: 14454: 14446: 14438: 14432: 14428: 14424: 14423: 14415: 14408: 14402: 14398: 14397: 14389: 14387: 14385: 14383: 14378: 14368: 14365: 14363: 14360: 14358: 14355: 14353: 14350: 14348: 14345: 14344: 14335: 14332: 14325: 14321: 14315: 14309: 14303: 14297: 14291: 14285: 14282: 14275: 14271: 14267: 14261: 14255: 14251: 14244: 14238: 14235: 14230: 14221: 14220:binary system 14217: 14213: 14209: 14205: 14202: 14195: 14191: 14185: 14179: 14178: 14175: 14164: 14155: 14149: 14143: 14139: 14136: 14129: 14125: 14119: 14115: 14111: 14105: 14102: 14095: 14089: 14085: 14079: 14071: 14070: 14067: 14063: 14059: 14050: 14043: 14039: 14033: 14027: 14023: 14020: 14013: 14009: 14002: 13996: 13993: 13992:variable star 13988: 13979: 13973: 13969: 13966: 13960: 13956: 13952: 13951:physical laws 13948: 13944: 13940: 13934: 13928: 13922: 13918: 13914: 13911: 13905: 13904: 13901: 13897: 13889: 13884: 13876: 13873: 13866: 13860: 13854: 13847: 13844: 13837: 13831: 13830:emission line 13827: 13823: 13821:spiral galaxy 13817: 13811: 13807: 13804: 13797: 13791: 13785: 13779: 13775: 13769: 13763: 13747: 13741: 13738: 13737:tropical year 13732: 13729: 13722: 13716: 13710: 13704: 13700: 13694: 13688: 13684: 13681: 13675: 13669: 13666: 13660: 13656: 13648: 13647: 13639: 13634: 13631: 13624: 13616: 13610: 13604: 13598: 13592: 13586: 13580: 13574: 13568: 13567: 13564: 13551: 13544: 13538: 13532: 13524: 13518: 13512: 13506: 13498: 13492: 13486: 13480: 13474: 13470: 13468:tidal braking 13464: 13461: 13460:tidal locking 13455: 13452: 13445: 13439: 13433: 13427: 13426: 13423: 13415: 13414:tidal braking 13408: 13402: 13396: 13390: 13384: 13381: 13375: 13372: 13364: 13361: 13354: 13348: 13342: 13336: 13333: 13326: 13320: 13314: 13308: 13302: 13296: 13293: 13286: 13282: 13278: 13274: 13268: 13265:telluric star 13261: 13258: 13251: 13249:proper motion 13245: 13239: 13233: 13229: 13223: 13214: 13211: 13204: 13198: 13192: 13186: 13180: 13177: 13170: 13164: 13160: 13154: 13148: 13146:same location 13142: 13136: 13130: 13127: 13120: 13114: 13108: 13102: 13096: 13090: 13084: 13080: 13074: 13068: 13062: 13056: 13055: 13052: 13044: 13037: 13031: 13025: 13019: 13013: 13007: 13004: 12989: 12983: 12979: 12973: 12967: 12963: 12959: 12952: 12946: 12940: 12934: 12928: 12923:An extremely 12922: 12919: 12912: 12906: 12904:galactic core 12900: 12894: 12888: 12884: 12877: 12876: 12869: 12865: 12860: 12856: 12852: 12846: 12843: 12837: 12834: 12828: 12825: 12818: 12812: 12806: 12801:), including 12800: 12794: 12790: 12784: 12783: 12780: 12772: 12765: 12759: 12753: 12750: 12743: 12739: 12734:that studies 12733: 12727: 12724: 12718: 12715: 12709: 12706: 12699: 12697:coronal loops 12693: 12687: 12681: 12677: 12673: 12670: 12663: 12657: 12655:astrophysical 12651: 12650: 12647: 12646:stellar model 12635: 12632: 12625: 12619: 12613: 12610: 12604: 12601: 12595: 12592: 12586: 12583: 12576: 12570: 12565:. The modern 12564: 12558: 12552: 12551: 12548: 12540: 12533: 12527: 12526: 12523: 12515: 12508: 12502: 12496: 12488: 12484: 12480: 12476: 12470: 12464: 12458: 12450: 12445: 12439: 12436: 12429: 12423: 12417: 12411: 12405: 12403:star clusters 12399: 12393: 12387: 12386: 12383: 12375: 12369: 12366: 12360: 12359: 12356: 12353:Also spelled 12348: 12341: 12335: 12329: 12325: 12321: 12317: 12311: 12307: 12303: 12299: 12296: 12273: 12269: 12265: 12261: 12260: 12257: 12244: 12235: 12230: 12224: 12221: 12220:spiral galaxy 12214: 12208: 12204: 12198: 12192: 12191: 12188: 12180: 12174: 12171: 12163: 12162: 12160:spectroscopic 12153: 12148: 12145: 12138: 12132: 12128: 12124: 12118: 12112: 12109: 12102: 12101: 12094: 12091: 12084: 12077: 12072:, called the 12071: 12069:June solstice 12065: 12059: 12053: 12047: 12044: 12037: 12031: 12025: 12019: 12013: 12007: 12003: 11999: 11995: 11992: 11985: 11979: 11977:sidereal time 11973: 11967: 11961: 11955: 11949: 11943: 11937: 11931: 11928: 11921: 11915: 11909: 11903: 11897: 11895:dwarf planets 11891: 11885: 11879: 11873: 11870: 11863: 11862: 11855: 11852: 11845: 11839: 11838:optical depth 11836:at which the 11835: 11829: 11823: 11812: 11805: 11799: 11793: 11787: 11781: 11778: 11771: 11764: 11751: 11745: 11734: 11728: 11725: 11724:solar granule 11719: 11716: 11709: 11705: 11699: 11695: 11691: 11685: 11682: 11675: 11669: 11663: 11656: 11650: 11644: 11638: 11632: 11629: 11628:solar eclipse 11622: 11619: 11613: 11607: 11601: 11595: 11589: 11583: 11577: 11571: 11565: 11559: 11556: 11550: 11546: 11539: 11538: 11531: 11525: 11519: 11513: 11509: 11505: 11502: 11496: 11493: 11492:sidereal year 11486: 11480: 11474: 11468: 11462: 11456: 11453: 11452:sidereal time 11446: 11440: 11434: 11428: 11422: 11419: 11412: 11406: 11400: 11394: 11388: 11382: 11376: 11373: 11366: 11365: 11363:March equinox 11358: 11354: 11350: 11346: 11340: 11334: 11333: 11330: 11322: 11315: 11309: 11304: 11298: 11294: 11293: 11290: 11282: 11275: 11272: 11271:semi-diameter 11265: 11259: 11256:selenocentric 11251: 11245: 11241: 11237: 11234: 11227: 11219: 11213: 11209: 11205: 11199: 11193: 11192: 11189: 11181: 11180:scintillation 11175: 11172: 11165: 11159: 11155: 11151: 11145: 11142: 11135: 11129: 11126:Saber's beads 11123: 11114: 11110: 11106: 11100: 11094: 11086: 11080: 11074: 11068: 11062: 11059: 11052: 11051: 11049:optical depth 11044: 11038: 11032: 11028: 11025: 11018: 11012: 11006: 11000: 10994: 10988: 10987: 10984: 10980: 10979:orphan planet 10976: 10972: 10964: 10957: 10953: 10947: 10941: 10938: 10931: 10930: 10923: 10919: 10917:giant planets 10913: 10907: 10901: 10895: 10889: 10883: 10880: 10873: 10867: 10863: 10857: 10854: 10846: 10845: 10837: 10831: 10830: 10823: 10817: 10813: 10807: 10804: 10796: 10793: 10787: 10784: 10777: 10771: 10765: 10761: 10755: 10749: 10743: 10737: 10734: 10728: 10725: 10718: 10714: 10713:helium fusion 10709: 10705: 10699: 10693: 10690: 10683: 10677: 10673: 10667: 10664: 10657: 10653: 10649: 10645: 10640:that studies 10639: 10633: 10630: 10623: 10619: 10613: 10609: 10606: 10601: 10592: 10588: 10584: 10580: 10576: 10572: 10566: 10560: 10554: 10548: 10547: 10545: 10537: 10528: 10527: 10519: 10513: 10507: 10501: 10495: 10489: 10483: 10480: 10473: 10470: 10466: 10462: 10458: 10452: 10443: 10437: 10431: 10428: 10421: 10417: 10413: 10409: 10401: 10397: 10394: 10388: 10385: 10378: 10376:planetesimals 10372: 10366: 10360: 10354: 10351: 10344: 10341: 10340:proper motion 10334: 10333:line-of-sight 10330: 10324: 10318: 10314: 10306: 10305: 10298: 10292: 10288: 10282: 10281: 10278: 10277:direct motion 10270: 10263: 10257: 10256: 10253: 10249: 10245: 10237: 10231: 10228: 10221: 10217: 10213: 10209: 10203: 10197: 10194: 10187: 10181: 10175: 10171: 10165: 10162: 10155: 10149: 10143: 10140: 10133: 10127: 10121: 10115: 10109: 10105: 10099: 10096: 10090: 10089: 10086: 10082: 10073: 10066: 10060: 10058:planetesimals 10054: 10048: 10042: 10036: 10034:dwarf planets 10030: 10024: 10018: 10012: 10006: 10000: 9996: 9993: 9986: 9980: 9974: 9968: 9967: 9964: 9956: 9949: 9945: 9939: 9933: 9929: 9926: 9919: 9916: 9909: 9907:planetesimals 9903: 9897: 9891: 9885: 9879: 9875: 9869: 9868: 9865: 9857: 9850: 9844: 9836: 9832: 9830:planetesimals 9826: 9820: 9816: 9812: 9808: 9803: 9797: 9794: 9787: 9781: 9773: 9767: 9761: 9755: 9749: 9743: 9737: 9733: 9732: 9729: 9721: 9715: 9712: 9706: 9703: 9696: 9692: 9688: 9682: 9678: 9672: 9666: 9663: 9656: 9651: 9645: 9639: 9633: 9627: 9624: 9617: 9616: 9609: 9603: 9600: 9593: 9592: 9585: 9579: 9573: 9570: 9563: 9562: 9555: 9549: 9548: 9545: 9537: 9530: 9526: 9522: 9515: 9512: 9505: 9501: 9498:of the words 9497: 9493: 9487: 9481: 9477: 9471: 9467: 9459: 9453: 9452: 9444: 9440: 9431: 9425: 9421: 9415: 9411: 9410: 9407: 9399: 9392: 9388: 9386:perturbations 9382: 9376: 9370: 9367: 9361: 9353: 9347: 9341: 9335: 9329: 9325: 9322: 9321:orbital speed 9314: 9313: 9304: 9298: 9292: 9286: 9282: 9279: 9273: 9267: 9263: 9257: 9251: 9245: 9239: 9233: 9230: 9223: 9217: 9211: 9205: 9201: 9195: 9189: 9183: 9179: 9176: 9175:orbital plane 9169: 9163: 9157: 9151: 9145: 9144: 9141: 9133: 9126: 9120: 9114: 9108: 9102: 9096: 9090: 9084: 9081: 9075: 9072: 9065: 9059: 9057:orbital plane 9053: 9047: 9044: 9036: 9030: 9028:orbital plane 9024: 9023: 9015: 9009: 9003: 9000: 8993: 8987: 8981: 8978: 8971: 8967: 8961: 8955: 8954: 8951: 8937: 8931: 8925: 8919: 8913: 8907: 8901: 8897: 8894: 8886: 8883: 8876: 8870: 8867: 8860: 8856: 8853: 8846: 8840: 8836: 8830: 8824: 8822:planetesimals 8818: 8817: 8814: 8806: 8799: 8793: 8787: 8781: 8775: 8772: 8765: 8759: 8753: 8747: 8741: 8738: 8732: 8729: 8722: 8716: 8710: 8704: 8698: 8692: 8686: 8680: 8679: 8676: 8668: 8661: 8660: 8653: 8650: 8643: 8637: 8631: 8628: 8621: 8620:variable star 8617: 8613: 8609: 8606:A diagram of 8605: 8599: 8590: 8584: 8578: 8572: 8569: 8562: 8559: 8552: 8548: 8541: 8535: 8529: 8523: 8517: 8513: 8507: 8504: 8497: 8491: 8485: 8479: 8473: 8467: 8464:is below the 8463: 8457: 8453: 8447: 8444: 8438: 8434: 8427: 8421: 8417: 8413: 8407: 8404: 8396: 8393: 8386: 8380: 8378:star clusters 8374: 8368: 8367:ionized gases 8364: 8360: 8356: 8350: 8344: 8338: 8335: 8328: 8322: 8316: 8310: 8306: 8300: 8295:, such as an 8294: 8288: 8284: 8277: 8271: 8265: 8259: 8253: 8247: 8246: 8243: 8235: 8227: 8226: 8223: 8219: 8211: 8204: 8198: 8192: 8186: 8183: 8176: 8172: 8168: 8164: 8160: 8156: 8150: 8142: 8139: 8132: 8126: 8120: 8116: 8112: 8106: 8100: 8094: 8091: 8084: 8078: 8072: 8066: 8065: 8062: 8054: 8047: 8041: 8035: 8034: 8031: 8023: 8022:morning width 8017: 8016: 8013: 8005: 7998: 7997: 7990: 7987: 7980: 7979: 7972: 7971: 7964: 7958: 7952: 7946: 7940: 7939: 7936: 7932: 7924: 7917: 7913: 7907: 7901: 7895: 7893:tidal locking 7889: 7883: 7877: 7874: 7867: 7866: 7859: 7856: 7849: 7848: 7845: 7837: 7830: 7826: 7820: 7817: 7810: 7809: 7802: 7801: 7794: 7788: 7782: 7779: 7772: 7766: 7760: 7754: 7748: 7742: 7739: 7732: 7731: 7724: 7721: 7713: 7710: 7708:constellation 7704: 7703: 7696: 7689: 7683: 7680: 7674: 7667: 7661: 7655: 7649: 7643: 7638: 7636:barred spiral 7632: 7629: 7622: 7616: 7610: 7608:variable star 7604: 7601:microvariable 7596: 7590: 7585:A very small 7584: 7581: 7574: 7568: 7564: 7560: 7555:A very small 7554: 7551: 7544: 7540: 7536: 7533: 7526: 7520: 7514: 7508: 7502: 7499: 7498:meteor shower 7492: 7486: 7480: 7477: 7470: 7464: 7461: 7454: 7453:incandescence 7450: 7444: 7438: 7432: 7426: 7420: 7419: 7416: 7412: 7411:shooting star 7404: 7397: 7391: 7387: 7381: 7375: 7372: 7365: 7359: 7354:and of their 7353: 7347: 7341: 7333: 7327: 7321: 7318: 7311: 7310: 7303: 7295: 7289: 7283: 7277: 7271: 7265: 7259: 7253: 7247: 7242: 7237: 7230: 7229: 7222: 7218: 7214: 7210: 7204: 7198: 7197: 7194: 7186: 7185:March equinox 7179: 7178: 7171: 7168: 7161: 7155: 7151: 7147: 7143: 7137: 7131: 7125: 7122: 7121:main sequence 7115: 7111: 7105: 7101: 7098: 7091: 7085: 7079: 7073: 7070: 7069:magnetosphere 7063: 7061:rogue planets 7057: 7051: 7049:neutron stars 7045: 7039: 7033: 7029: 7025: 7019: 7015: 7010: 7000: 6999: 6991: 6985: 6979: 6973: 6969: 6965: 6959: 6953: 6951:synodic month 6947: 6941: 6940: 6937: 6929: 6922: 6916: 6908: 6902: 6896: 6892: 6888: 6884: 6878: 6872: 6866: 6863: 6856: 6850: 6844: 6838: 6832: 6826: 6822: 6816: 6813: 6806: 6800: 6794: 6788: 6782: 6775:of the image. 6774: 6773: 6768: 6762: 6759: 6752: 6746: 6740: 6718: 6712: 6706: 6702: 6695: 6694: 6689: 6685: 6681: 6675: 6672: 6666: 6663: 6657: 6656: 6653: 6649: 6645: 6637: 6630: 6624: 6618: 6611: 6603: 6599: 6595: 6590: 6584: 6578: 6577: 6574: 6570: 6566: 6558: 6553: 6544: 6540: 6538:dwarf planets 6534: 6532:asteroid belt 6528: 6522: 6516: 6511:in the outer 6510: 6504: 6498: 6492: 6486: 6480: 6479: 6476: 6468: 6461: 6459:perturbations 6455: 6453:orbital plane 6449: 6445: 6441: 6437: 6431: 6430: 6427: 6419: 6413: 6410: 6405: 6396: 6390: 6384: 6382:tropical year 6377: 6373: 6369: 6362: 6356: 6353: 6348: 6339: 6333: 6327: 6321: 6318: 6311: 6307: 6305:regular moons 6301: 6295: 6289: 6283: 6277: 6271: 6268: 6262: 6259: 6253: 6250: 6243: 6237: 6233: 6227: 6221: 6220: 6217: 6216:Laplace plane 6213: 6205: 6198: 6192: 6186: 6183: 6176: 6172: 6168: 6162: 6156: 6152: 6148: 6142: 6138: 6131: 6127: 6122:that studies 6121: 6115: 6112: 6105: 6101: 6095: 6091: 6086: 6082: 6076: 6072: 6068: 6065: 6058: 6057: 6050: 6047: 6040: 6034: 6030: 6026: 6020: 6016: 6012: 6008: 6004: 6000: 5996: 5990: 5987: 5982: 5973: 5969: 5963: 5957: 5953: 5947: 5941: 5933: 5927: 5921: 5915: 5907: 5903: 5897: 5893: 5889: 5885: 5877: 5871: 5865: 5859: 5853: 5849: 5846: 5839: 5833: 5827: 5821: 5817: 5811: 5805: 5799: 5793: 5787: 5784: 5777: 5771: 5767: 5764: 5757: 5755:galactic core 5751: 5745: 5739: 5738: 5735: 5727: 5720: 5714: 5708: 5706:main-sequence 5702: 5696: 5690: 5684: 5682:spectral type 5678: 5672: 5666: 5660: 5654: 5648: 5645: 5638: 5632: 5626: 5620: 5614: 5611: 5605: 5602: 5595: 5589: 5583: 5580: 5573: 5569: 5563: 5559: 5551: 5545: 5538: 5534: 5531: 5527: 5523: 5517: 5514: 5509: 5500: 5494: 5488: 5482: 5480:neutron stars 5476: 5472: 5468: 5462: 5459: 5452: 5451:Einstein ring 5448: 5447: 5439: 5433: 5429: 5423: 5420: 5414: 5411: 5404: 5402:open clusters 5398: 5392: 5390:galactic core 5386: 5380: 5374: 5371: 5364: 5358: 5352: 5346: 5343: 5336: 5330: 5324: 5318: 5312: 5306: 5300: 5296: 5289: 5283: 5279: 5273: 5267: 5262: 5256: 5255: 5252: 5248: 5240: 5233: 5227: 5221: 5215: 5209: 5201: 5197: 5193: 5187: 5184: 5177: 5171: 5165: 5159: 5151: 5147: 5141: 5138: 5131: 5127: 5123: 5120: 5113: 5107: 5103: 5099: 5095: 5091: 5085: 5082: 5075: 5073:neutron stars 5069: 5063: 5057: 5051: 5047: 5043: 5036: 5032: 5027:that studies 5026: 5020: 5017: 5010: 5006: 5002: 4998: 4994: 4990: 4986: 4980: 4977: 4970: 4968:superclusters 4964: 4958: 4952: 4946: 4945: 4942: 4934: 4927: 4925:superclusters 4921: 4919:galaxy groups 4915: 4913:star clusters 4909: 4903: 4897: 4894: 4887: 4881: 4875: 4869: 4863: 4857: 4851: 4845: 4839: 4833: 4827: 4821: 4818: 4811: 4805: 4799: 4795: 4789: 4783: 4777: 4771: 4763: 4757: 4751: 4747: 4741: 4738: 4737:galactic tide 4731: 4725: 4719: 4713: 4707: 4701: 4695: 4694: 4691: 4687: 4686:galactic year 4679: 4672: 4666: 4660: 4654: 4648: 4642: 4641: 4638: 4634: 4633:galactic core 4626: 4620: 4617: 4611: 4608: 4601: 4597: 4593: 4590: 4584: 4578: 4572: 4567: 4561: 4555: 4552: 4545: 4542: 4540:constellation 4536: 4530: 4524: 4518: 4515: 4508: 4502: 4497: 4491: 4488: 4483: 4474: 4468: 4465: 4458: 4452: 4448: 4444: 4440: 4436: 4434:variable star 4430: 4427: 4420: 4414: 4408: 4402: 4396: 4390: 4384: 4378: 4377: 4374: 4366: 4359: 4353: 4347: 4341: 4338: 4336:constellation 4332: 4326: 4320: 4314: 4311: 4304: 4298: 4292: 4286: 4280: 4277: 4275:constellation 4271: 4265: 4259: 4257:March equinox 4253: 4252: 4249: 4248:Cusp of Aries 4240: 4233: 4229: 4226: 4219: 4213: 4207: 4204: 4197: 4191: 4190:line of sight 4187: 4181: 4173: 4167: 4164: 4157: 4151: 4145: 4139: 4135: 4129: 4123: 4120: 4115: 4106: 4105: 4098: 4090: 4084: 4078: 4077: 4074: 4066: 4059: 4053: 4047: 4041: 4035: 4032: 4025: 4019: 4014: 4008: 4005: 3998: 3994: 3990: 3984: 3980: 3976: 3972: 3969: 3961: 3960: 3952: 3946: 3940: 3934: 3928: 3922: 3919: 3912: 3906: 3902: 3898: 3893: 3890: 3883: 3882: 3875: 3869: 3863: 3857: 3851: 3845: 3839: 3833: 3827: 3821: 3815: 3812: 3805: 3799: 3791: 3785: 3779: 3774:(forming the 3773: 3767: 3761: 3757: 3751: 3748: 3741: 3735: 3731: 3725: 3721: 3715: 3712: 3704: 3702:perturbations 3698: 3692: 3686: 3680: 3677: 3670: 3664: 3658: 3652: 3649: 3642: 3636: 3630: 3626: 3623: 3615: 3614: 3606: 3600: 3596: 3590: 3584: 3578: 3572: 3571: 3568: 3560: 3553: 3547: 3541: 3537: 3531: 3528: 3521: 3517: 3513: 3510: 3503: 3497: 3491: 3485: 3479: 3473: 3467: 3463: 3457: 3451: 3445: 3442: 3434: 3427: 3421: 3415: 3409: 3408: 3400: 3395:of the Earth. 3394: 3388: 3382: 3376: 3370: 3364: 3358: 3352: 3351:Earth's orbit 3348: 3344: 3343: 3340: 3336: 3328: 3321: 3320: 3313: 3310: 3302: 3296: 3293: 3288: 3279: 3273: 3267: 3261: 3255: 3251: 3247: 3244: 3238: 3232: 3230:main-sequence 3226: 3220: 3217: 3211: 3208: 3201: 3194: 3188: 3185: 3178: 3174: 3168: 3162: 3156: 3150: 3144: 3138: 3135: 3128: 3127: 3120: 3117: 3116:direct motion 3110: 3104: 3098: 3092: 3088: 3082: 3076: 3070: 3064: 3063: 3060: 3056: 3048: 3041: 3040: 3033: 3027: 3021: 3015: 3014: 3011: 3003: 2996: 2990: 2984: 2978: 2972: 2968: 2965: 2958: 2952: 2946: 2944:star clusters 2940: 2934: 2928: 2922: 2916: 2910: 2906: 2899: 2895: 2889: 2883: 2880: 2873: 2872: 2865: 2859: 2855: 2849: 2846: 2838: 2834: 2833: 2825: 2819: 2815: 2813:planetesimals 2809: 2803: 2800: 2795: 2786: 2782: 2778: 2772: 2768: 2762: 2756: 2750: 2748:constellation 2744: 2738: 2732: 2726: 2720: 2714: 2713: 2710: 2702: 2695: 2694: 2687: 2681: 2678:balances the 2677: 2673: 2672: 2669: 2657: 2649: 2643: 2639: 2636: 2629: 2625: 2619: 2616: 2609: 2603: 2597: 2593: 2589: 2586: 2580: 2579: 2576: 2567: 2560: 2554: 2551: 2550: 2547: 2539: 2533: 2530: 2523: 2517: 2511: 2505: 2499: 2495: 2491: 2485: 2482: 2475: 2473:solar eclipse 2469: 2463: 2459: 2456: 2449: 2448: 2441: 2435: 2431: 2425: 2422: 2421:constellation 2415: 2409: 2403: 2399: 2393: 2390: 2383: 2382: 2375: 2372: 2365: 2359: 2353: 2351:neutron stars 2347: 2341: 2335: 2334: 2331: 2323: 2316: 2312: 2306: 2304:proper motion 2300: 2296: 2288: 2284: 2280: 2277: 2273: 2267: 2264: 2257: 2253: 2249: 2245: 2239: 2236: 2229: 2226:bands of the 2225: 2221: 2218: 2212: 2209: 2203: 2196: 2195: 2192: 2189:Also spelled 2184: 2176: 2167: 2164: 2160: 2156: 2155:H and K lines 2152: 2148: 2143: 2134: 2125: 2119: 2115: 2108: 2105: 2098: 2092: 2086: 2080: 2076: 2069: 2067:giant planets 2063: 2057: 2051: 2045: 2039: 2033: 2031:outer planets 2027: 2021: 2015: 2009: 2006: 1999: 1993: 1987: 1981: 1978: 1971: 1965: 1959: 1953: 1947: 1941: 1938: 1931: 1930: 1923: 1920: 1913: 1907: 1901: 1895: 1889: 1883: 1879: 1873: 1870: 1862: 1856: 1850: 1844: 1843: 1836: 1829: 1823: 1817: 1811: 1805: 1799: 1793: 1789: 1786: 1779: 1775: 1771: 1767: 1759: 1756: 1751: 1743: 1740: 1733: 1729: 1723: 1721:main sequence 1717: 1713: 1709: 1703: 1700: 1693: 1689: 1685: 1684: 1681: 1677: 1676: 1661: 1658: 1651: 1649:event horizon 1645: 1642: 1635: 1631: 1625: 1619: 1613: 1607: 1604: 1597: 1591: 1585: 1582: 1575: 1571: 1568: 1561: 1555: 1549: 1543: 1539: 1533: 1529: 1523: 1519: 1516: 1508: 1502: 1501: 1493: 1489: 1480: 1476: 1472: 1468: 1465: 1459: 1456: 1449: 1443: 1439: 1433: 1431:orbital plane 1427: 1421: 1420: 1417: 1409: 1402: 1396: 1390: 1386: 1380: 1376: 1370: 1364: 1358: 1354: 1348: 1342: 1336: 1333: 1325: 1322: 1315: 1309: 1305: 1301: 1297: 1293: 1287: 1283: 1279: 1276: 1270: 1267: 1260: 1254: 1248: 1245: 1230: 1229:Earth's orbit 1226: 1222: 1216: 1212: 1205: 1199: 1195: 1191: 1185: 1179: 1174: 1168: 1162: 1156: 1150: 1144: 1141: 1134: 1128: 1122: 1116: 1110: 1104: 1098: 1097: 1094: 1086: 1079: 1078: 1075: 1072:Also spelled 1067: 1060: 1054: 1048: 1042: 1036: 1030: 1024: 1023: 1020: 1012: 1005: 999: 993: 990: 983: 982: 975: 969: 967:binary system 963: 960: 952: 951: 948: 940: 933: 932: 925: 922: 921:astrodynamics 915: 914:biosignatures 911: 907: 901: 897: 893: 889: 883: 882: 879: 871: 864: 860: 856: 854:minor planets 850: 844: 838: 834: 830: 824: 818: 815: 814:asteroid belt 808: 802: 800:planetesimals 796: 790: 784: 778: 772: 768: 762: 757:of the inner 756: 750: 747: 740: 738:constellation 734: 728: 722: 719: 712: 706: 700: 694: 686: 685: 678: 672: 666: 660: 654: 648: 647: 644: 636: 629: 628: 621: 615: 609: 606: 599: 593: 587: 581: 575: 574: 571: 567: 559: 552: 546: 540: 534: 528: 522: 516: 513: 506: 503: 496: 492: 491: 488: 480: 473: 472: 465: 459: 453: 450: 443: 442: 435: 429: 426: 419: 418: 411: 405: 402: 395: 394: 387: 381: 377: 374: 367: 361: 358: 350: 346: 345: 338: 334: 328: 324: 318: 314: 308: 302: 298: 295: 288: 287:active galaxy 284: 278: 274: 268: 262: 258: 251: 245: 239: 233: 230: 223: 217: 211: 205: 199: 196: 189: 183: 181:main-sequence 177: 171: 168: 163: 153: 150: 148: 145: 143: 140: 138: 135: 132: 129: 126: 123: 120: 117: 114: 111: 108: 105: 102: 99: 96: 93: 90: 87: 84: 81: 78: 75: 72: 69: 66: 63: 60: 59: 51: 49: 45: 41: 37: 33: 19: 16904:Engineering 16855:Cell biology 16834: 16825:Architecture 16577: 16557:Astrophysics 16536:Astrobiology 16200:Far-infrared 16154:Local system 16089:Astronomy by 16079:... in space 16071: 15976:, retrieved 15971: 15958:, retrieved 15953: 15940:, retrieved 15935: 15922:, retrieved 15916: 15906:, retrieved 15901: 15868: 15861: 15818: 15814: 15808: 15765: 15761: 15755: 15731: 15724: 15681: 15677: 15671: 15651: 15644: 15620: 15613: 15603:, retrieved 15599:the original 15594: 15585: 15566: 15559: 15539: 15532: 15521:, retrieved 15515: 15509: 15498:, retrieved 15492: 15486: 15466: 15459: 15442: 15438: 15431: 15411: 15404: 15369: 15365: 15359: 15342: 15338: 15332: 15312: 15305: 15285: 15278: 15256: 15250: 15241: 15235: 15218: 15212: 15179: 15175: 15169: 15158:, retrieved 15153: 15143: 15132:, retrieved 15127: 15117: 15098: 15091: 15074: 15070: 15064: 15037: 15008: 15002: 14957: 14953: 14947: 14912: 14908: 14902: 14885: 14881: 14875: 14865:, retrieved 14861:the original 14856: 14808:, retrieved 14806:, 2017-02-14 14803: 14794: 14783:, retrieved 14764: 14757: 14746:, retrieved 14727: 14720: 14707: 14702: 14667: 14663: 14657: 14639: 14633: 14588: 14584: 14578: 14558: 14551: 14524: 14520: 14507: 14482: 14478: 14472: 14452: 14445: 14421: 14414: 14395: 14212:neutron star 14206:A source of 14201:X-ray source 14173: 14170: 14065: 14061: 14057: 14054: 13958: 13899: 13895: 13892: 13852:astronomical 13789:mean anomaly 13746:true anomaly 13642: 13608:eccentricity 13587:), used for 13562: 13559: 13529:tilt erosion 13519:such as the 13507:A stream of 13503:tidal stream 13431:tidal forces 13421: 13418: 13184:conjunctions 13176:synodic time 13106:eccentricity 13094:sidereal day 13050: 13047: 12944:evolutionary 12871: 12833:supercluster 12804:brown dwarfs 12798:solar masses 12778: 12775: 12749:subsatellite 12645: 12644:Also simply 12642: 12546: 12543: 12521: 12518: 12381: 12378: 12365:star cluster 12355:star catalog 12354: 12351: 12262:The nominal 12255: 12252: 12242: 12233: 12193:A branch of 12186: 12183: 12157: 12144:spectroscopy 12096: 11869:Solar System 11857: 11811:solar radius 11681:solar facula 11617: 11599:sidereal day 11533: 11478:sidereal day 11432:Solar System 11372:sidereal day 11360: 11356: 11352: 11328: 11325: 11307:Kepler orbit 11288: 11285: 11187: 11184: 11084:sidereal day 11046: 10982: 10978: 10975:nomad planet 10974: 10970: 10967: 10963:rogue planet 10925: 10840: 10825: 10818:such as the 10766:about their 10763: 10733:regular moon 10663:radio source 10585:, and their 10543: 10540: 10522: 10469:longitudinal 10435:neutron star 10322:double stars 10300: 10293:such as the 10276: 10273: 10252:central body 10251: 10248:primary body 10247: 10243: 10240: 10211: 10153:dwarf planet 10147:minor planet 10119:debris disks 10095:planetesimal 10084: 10080: 10077: 10064:debris discs 9962: 9959: 9895:dwarf planet 9863: 9860: 9834: 9727: 9724: 9643:Kepler orbit 9623:perturbation 9611: 9587: 9557: 9543: 9540: 9503: 9499: 9447: 9414:nearly empty 9405: 9402: 9374:Kepler orbit 9308: 9277:dwarf planet 9265: 9249:eccentricity 9221:Solar System 9161:Solar System 9139: 9136: 9080:orbital node 9018: 8950:orbital plot 8949: 8946: 8866:open cluster 8844:Solar System 8812: 8809: 8690:Solar System 8684:observations 8674: 8671: 8655: 8611: 8607: 8411:compact star 8403:neutron star 8365:, and other 8269:minor planet 8241: 8238: 8221: 8217: 8214: 8060: 8057: 8053:moving group 8029: 8026: 8011: 8008: 7995:subsatellite 7992: 7977:subsatellite 7974: 7966: 7962:minor planet 7956:dwarf planet 7934: 7930: 7927: 7915: 7861: 7843: 7840: 7807:subsatellite 7804: 7796: 7792:minor planet 7738:minor planet 7726: 7698: 7675:, which the 7647:Solar System 7503:A series of 7415:falling star 7414: 7410: 7407: 7305: 7287:true anomaly 7278:in the same 7240: 7236:mean anomaly 7224: 7220: 7216: 7192: 7189: 7173: 7102:A numerical 7055:brown dwarfs 7032:galaxy halos 6994: 6971: 6967: 6935: 6932: 6770: 6691: 6651: 6647: 6643: 6640: 6613: 6606: 6572: 6568: 6564: 6561: 6541:, including 6514:Solar System 6474: 6471: 6425: 6422: 6418:Kepler orbit 6331:evolutionary 6309: 6284:, and often 6215: 6211: 6208: 6132:wavelengths. 6052: 6038:Solar System 5994:giant planet 5931:brown dwarfs 5852:great circle 5788:For a given 5733: 5730: 5636:Solar System 5579:heliocentric 5560:The precise 5526:O-type stars 5463:A branch of 5442: 5431: 5353:, including 5342:giant planet 5322:sidereal day 5250: 5246: 5243: 5111:Solar System 5089:giant planet 5037:wavelengths. 4940: 4937: 4933:galaxy group 4758:such as the 4723:Solar System 4689: 4685: 4682: 4636: 4632: 4629: 4582:solar masses 4394:Solar System 4372: 4369: 4247: 4244: 4195:star cluster 4163:field galaxy 4149:solar facula 4103:astrobiology 4100: 4088:Solar System 4072: 4069: 4045:Solar System 3955: 3877: 3867:September 22 3786:towards the 3631:between the 3609: 3576:Kepler orbit 3566: 3563: 3501:inclinations 3480:towards the 3455:Solar System 3403: 3374:Solar System 3338: 3334: 3331: 3315: 3309:eccentricity 3277:brown dwarfs 3265:white dwarfs 3207:dwarf planet 3189:Any pair of 3176: 3122: 3080:Solar System 3074:minor planet 3058: 3054: 3051: 3035: 3034:). Contrast 3031:Solar System 3019:orbital node 3009: 3006: 2982:neutron star 2926:Solar System 2867: 2831:debris disks 2828: 2784: 2780: 2770: 2708: 2705: 2689: 2667: 2664: 2607:Solar System 2574: 2571: 2545: 2542: 2481:coronal loop 2443: 2410:or the same 2377: 2345:white dwarfs 2329: 2326: 2322:compact star 2190: 2187: 2171: 2159:photospheric 2149:of a star's 2138: 2129: 2123:chromosphere 2120:in a star's 2104:chromosphere 1925: 1890:, including 1838: 1794:of a body's 1792:great circle 1770:spectrograph 1679: 1671: 1668: 1567:baryogenesis 1496: 1415: 1412: 1389:polar motion 1275:astrophysics 1220:Solar System 1160:Solar System 1120:star cluster 1092: 1089: 1073: 1070: 1018: 1015: 977: 946: 943: 939:astrogeology 927: 900:habitability 877: 874: 870:astrobiology 862: 858: 828:Solar System 760:Solar System 754:minor planet 680: 664:Solar System 652:orbital node 642: 639: 623: 619:Solar System 569: 565: 562: 486: 483: 467: 437: 413: 389: 385:A-type stars 340: 337:Syrtis Major 309:, such as a 286: 31: 29: 17025:Ornithology 17010:Meteorology 16995:Mathematics 16985:Ichthyology 16820:Archaeology 16815:Agriculture 16799:engineering 16624:Planetarium 16281:High-energy 16267:Cosmic rays 16219:Ultraviolet 15345:: 126–140, 15182:: 681–694, 15128:www.gnu.org 15077:: 503–511, 14915:, id. A29, 14485:: 763–777, 14310:across the 14101:white dwarf 13714:occultation 13621:topocentric 13614:inclination 13451:tidal force 13300:heliosphere 13078:fixed stars 13043:synodic day 12950:white dwarf 12892:black holes 12870:. Contrast 12623:binary star 12506:star system 12459:Any set of 12397:binary star 12374:star system 12318:due to the 12315:outer space 12116:binary star 11851:solar storm 11833:photosphere 11797:photosphere 11715:solar flare 11689:photosphere 11636:occultation 11593:fixed stars 11563:synodic day 11532:. See also 11517:outer space 11466:fixed stars 11438:fixed stars 11389:of its own 11386:fixed stars 11313:binary star 11078:synodic day 10945:tidal force 10937:Roche limit 10924:. See also 10879:ring system 10824:. Contrast 10821:fixed stars 10717:core region 10676:radio waves 10587:ultraviolet 10579:radio waves 10441:white dwarf 10350:protoplanet 10299:. Contrast 10296:fixed stars 10179:inclination 10161:polar orbit 10131:protoplanet 10022:star system 9997:Any set of 9963:planetology 9948:Ring Nebula 9898:, or other 9851:or planets. 9833:. The term 9813:by its own 9785:inclination 9747:inclination 9711:photosphere 9662:phase angle 9556:. Contrast 9529:light curve 9496:portmanteau 9485:light-years 9398:outer space 9261:inclination 9196:around its 8939:trajectory. 8771:occultation 8720:uncertainty 8602:O–C diagram 8458:, when the 8398:undetected. 8222:unaided eye 8169:. Most are 8130:cosmic rays 7965:. See also 7959:, or other 7947:orbiting a 7795:. See also 7749:around the 7712:Sagittarius 7691:The bright 7665:light-years 7572:cosmic dust 7532:metallicity 7348:across the 7104:logarithmic 7052:as well as 7043:black holes 7028:dark matter 6928:lunar phase 6879:, or other 6812:Local Group 6716:Julian year 6467:Kuiper belt 6368:Julian year 6046:inclination 5938:hypergalaxy 5892:Delta Scuti 5845:hour circle 5815:hour circle 5734:Hill radius 5726:Hill sphere 5718:white dwarf 5700:metallicity 5676:color index 5610:heliosphere 5556:heliocenter 5530:Ultraviolet 5518:An ionized 5513:H II region 5486:black holes 5191:phase angle 5055:light-years 4849:dark matter 4798:kiloparsecs 4793:light-years 4745:tidal force 4714:around the 4690:cosmic year 4592:Sagittarius 4431:A class of 4365:fixed stars 4203:first light 4133:photosphere 3997:attenuation 3796:equinoctial 3540:ellipsoidal 3353:around the 3246:giant stars 3199:binary star 3184:double star 2976:white dwarf 2845:declination 2799:debris disk 2701:culmination 2688:. See also 2558:outer space 2538:cosmic dust 2515:solar flare 2460:An aura of 2389:conjunction 2357:black holes 2217:color index 2037:Kuiper belt 1963:fixed stars 1774:Coudé focus 1699:brown dwarf 1629:double star 1611:star system 1603:binary star 1520:The common 1506:binary star 1304:temperature 892:abiogenesis 701:or Earth's 622:. Contrast 436:. Contrast 392:metallicity 327:cloud cover 221:light-years 167:A-type star 17080:Categories 17040:Psychiatry 16949:Geography 16920:Entomology 16617:Photometry 16594:Binoculars 16571:Astrometry 16432:telescopes 16329:Babylonian 16173:EM methods 16051:Astronomer 15978:2012-02-20 15960:2018-03-09 15950:"Glossary" 15942:2018-03-09 15924:2018-03-09 15908:2012-02-19 15879:038794138X 15605:2012-02-27 15550:0521780918 15523:2011-10-20 15500:2011-10-20 15270:0486646874 15160:19 January 15134:19 January 14967:1805.12143 14922:1609.02864 14867:2021-11-22 14810:2019-03-09 14785:2016-10-15 14770:OUP Oxford 14748:2012-02-29 14373:References 14216:black hole 14106:A type of 14051:(Virgo SC) 13977:multiverse 13949:, and the 13849:including 13815:luminosity 13698:luminosity 13406:halo stars 13332:terminator 13318:solar wind 13112:axial tilt 13063:(i.e. its 12859:geocentric 12574:luminosity 12479:Betelgeuse 12336:, and its 12333:luminosity 12288: ft/s 12212:astrometry 12113:A type of 11991:solar wind 11927:solar time 11733:solar mass 11703:solar limb 11512:atmosphere 11349:North Pole 11302:elliptical 11208:turbulence 11197:brightness 11104:star spots 11098:luminosity 11036:atmosphere 10902:such as a 10843:retrograde 10558:luminosity 10525:quadrature 10493:elongation 10479:quadrature 10420:periastron 10261:barycenter 10193:precession 10052:meteoroids 10001:bound non- 9930:A type of 9821:) and has 9798:A type of 9670:elongation 9599:perihelion 9544:pericenter 9412:The vast, 9339:barycenter 8943:orbit plot 8882:opposition 8859:convection 8805:Oort cloud 8751:telescopes 8675:arc length 8658:axial tilt 8612:calculated 8588:precession 8539:retrograde 8486:, and the 8408:A type of 8372:luminosity 8138:multiverse 8110:extrasolar 8095:A type of 8030:rise width 7931:minor moon 7720:minor axis 7614:luminosity 7484:atmosphere 7448:atmosphere 7269:pericenter 7213:North Pole 7167:major axis 7154:hydrogen-1 7135:luminosity 7077:solar wind 7020:A kind of 6936:Moon phase 6862:luminosity 6744:astrometry 6733:10 mi 6725:10 km 6701:light-year 6394:light-year 6293:retrograde 6249:ionosphere 6225:barycenter 6190:extinction 6102:, such as 6085:geocentric 5956:elliptical 5919:luminosity 5783:hour angle 5749:satellites 5652:luminosity 5649:A plot of 5601:heliopause 5495:, and the 5492:supernovae 5362:ice giants 5356:gas giants 5231:aberration 5225:light-time 5200:Lambertian 5137:geocentric 4861:elliptical 4658:luminosity 4464:Fulton gap 4456:red dwarfs 4426:flare star 4412:extrasolar 4348:meets the 4293:meets the 4178:field star 4155:solar limb 4140:. For the 4095:exobiology 3979:scattering 3975:absorption 3968:extinction 3944:luminosity 3622:elongation 3573:A type of 3532:A type of 3516:black body 3392:axial tilt 3250:Betelgeuse 3216:dwarf star 3145:(e.g. the 3099:, such as 3010:south node 2721:(e.g. the 2590:A type of 2585:cosmic ray 2546:space dust 2402:spacecraft 2279:proportion 2163:bolometric 2019:perihelion 1845:, and the 1815:axial tilt 1768:This is a 1716:hydrogen-1 1641:black hole 1623:barycenter 1515:barycenter 1499:barycenter 1471:true north 1428:plane and 1425:equatorial 1408:axial tilt 1340:precession 1321:atmosphere 1296:luminosity 1180:, and the 1000:and other 989:astrometry 964:A type of 878:exobiology 794:planetoids 788:meteoroids 676:parameters 643:north node 495:atmosphere 416:perihelion 322:black body 315:, that is 272:luminosity 249:black hole 147:References 17091:Astronomy 16895:Economics 16860:Chemistry 16835:Astronomy 16689:Telescope 16295:Spherical 16242:Gamma-ray 16211:(optical) 16016:Astronomy 15716:118784209 15691:1101.2156 15396:120268049 15204:119578058 15057:18293428M 14994:119059288 14960:(2): 11, 14694:122679154 14298:) of the 14056:Also the 13955:constants 13894:Also the 13767:periapsis 13542:satellite 13536:obliquity 13522:Milky Way 13484:satellite 13388:Milky Way 13309:from the 13257:telescope 13152:night sky 13118:solar day 12996: m/s 12974:or other 12941:'s final 12932:transient 12918:supernova 12863:cosmology 12807:and some 12731:astronomy 12691:starspots 12682:inside a 12468:telescope 12455:starfield 12280: m/s 12122:telescope 12063:longitude 12002:electrons 11953:solar day 11907:asteroids 11800:into the 11620:solar day 11555:solar day 11536:night sky 11523:astronomy 11410:solar day 11188:twinkling 11163:Milky Way 10866:longitude 10715:in their 10654:known as 10637:astronomy 10564:accretion 10393:protostar 10358:planetary 10139:planetoid 10046:asteroids 10013:around a 9937:red giant 9841:planetary 9835:exoplanet 9536:periapsis 9480:arcsecond 9351:periapsis 9336:around a 8914:around a 8811:Also the 8696:asteroids 8649:obliquity 8456:nighttime 8443:night sky 8317:from the 8210:naked eye 8124:neutrinos 8113:origins: 8098:astronomy 7899:night sky 7653:night sky 7628:Milky Way 7620:magnitude 7588:meteoroid 7558:meteorite 7512:night sky 7490:meteorite 7476:meteoroid 7460:meteorite 7424:meteoroid 7263:periapsis 7191:Also the 7114:naked eye 7097:magnitude 6968:full moon 6792:periapsis 6671:libration 6652:Local SCI 6642:Also the 6523:from the 6496:asteroids 6448:hyperbola 6317:isochrone 6287:eccentric 6119:astronomy 6089:cosmology 6024:volatiles 6005:(such as 5986:ice giant 5972:Andromeda 5967:Milky Way 5898:. On the 5875:geocenter 5732:Also the 5712:red giant 5694:evolution 5473:known as 5471:spacetime 5396:satellite 5213:celestial 5169:geocenter 5119:geocenter 5081:gas giant 5067:hypernova 5061:supernova 5050:gamma ray 5035:gamma-ray 5024:astronomy 4995:in 1610: 4885:Milky Way 4873:irregular 4809:Milky Way 4761:Milky Way 4729:Milky Way 4702:within a 4596:Ophiuchus 4565:Milky Way 4495:Milky Way 4449:waves to 4388:night sky 4321:upon the 4260:upon the 4246:Also the 4211:telescope 4073:exoplanet 4012:Milky Way 3938:evolution 3843:longitude 3768:onto the 3648:ephemeris 3492:and many 3432:equinoxes 3274:known as 3262:known as 3172:night sky 3102:cubewanos 3071:class of 3068:dynamical 3008:Also the 2988:evolution 2973:, e.g. a 2938:night sky 2635:cosmology 2615:cosmogony 2592:radiation 2524:eruption. 2434:mythology 2274:are in a 2248:volatiles 2224:frequency 2055:asteroids 1877:astronomy 1732:deuterium 1416:obliquity 1400:night sky 1286:chemistry 1258:phenomena 1244:astronomy 1198:astrology 1189:equinoxes 1183:solstices 863:main belt 848:asteroids 732:night sky 641:Also the 591:periapsis 538:periapsis 440:periapsis 55:Contents 40:cosmology 36:astronomy 17065:Virology 17050:Robotics 17015:Mycology 17005:Medicine 16850:Calculus 16739:Category 16448:Category 16343:Egyptian 16260:Neutrino 16195:Infrared 16143:Galactic 16118:Sidewalk 16072:Glossary 16042:Timeline 15853:15648424 15800:17029463 15595:Galaxies 14625:14732824 14341:See also 14301:ecliptic 14144:and the 13972:causally 13926:galaxies 13910:universe 13843:twilight 13824:and its 13786:and the 13679:meridian 13572:asteroid 13443:prograde 13243:observer 13232:velocity 13083:sunrises 13020:with an 12926:luminous 12409:galaxies 12324:hydrogen 12302:spheroid 12127:spectrum 12043:solstice 11959:meridian 11904:such as 11818:☉ 11761:10 11740:☉ 11587:meridian 11484:meridian 10956:coalesce 10893:moonlets 10747:prograde 10724:redshift 10355:A large 9806:orbiting 9744:such as 9689:such as 9679:such as 9614:aphelion 9560:apoapsis 9500:parallax 9475:parallax 9450:parallax 9429:Universe 9237:orbiting 9209:ecliptic 9115:and the 9106:inclined 8644:O and B. 8608:observed 8568:nutation 8533:prograde 8516:coplanar 8514:that is 8474:such as 8416:neutrons 8392:neutrino 8384:galaxies 8359:hydrogen 8298:asteroid 8218:bare eye 8153:N galaxy 7986:moonmoon 7539:hydrogen 7442:asteroid 7351:meridian 7317:meridian 6972:new moon 6823:(☊ or Ω) 6801:) of an 6798:apoapsis 6795:and the 6738:galactic 6688:far side 6508:centaurs 6493:such as 6444:parabola 6435:orbiting 6391:and the 6281:inclined 6196:redshift 6171:hydrogen 6130:infrared 6015:nitrogen 5999:hydrogen 5869:meridian 5828:and the 5809:meridian 5572:spheroid 5498:Big Bang 5260:circular 5094:hydrogen 5009:Callisto 5005:Ganymede 4950:galaxies 4901:galaxies 4600:Scorpius 4057:galaxies 3993:observer 3991:and the 3880:solstice 3861:March 20 3852:and the 3579:with an 3327:ecliptic 3111:objects. 2956:galaxies 2941:such as 2898:Be stars 2858:latitude 2779:, and a 2754:meridian 2647:Universe 2623:universe 2446:asterism 2360:, or to 2276:rational 2153:calcium 2136:, where 1928:meridian 1854:ecliptic 1821:ecliptic 1581:Big Bang 1475:altitude 1384:nutation 1371:and the 1194:almanacs 1172:zodiacal 1052:asteroid 954:objects. 746:asteroid 718:asterism 579:orbiting 544:apoapsis 425:apoapsis 401:aphelion 142:See also 17030:Physics 16980:Geology 16890:Ecology 16840:Biology 16795:science 16751:Commons 16703:history 16673:Russian 16521:Related 16430:Optical 16415:Tibetan 16399:Serbian 16392:Persian 16336:Chinese 16313:Culture 16233:History 16104:Amateur 16035:History 16028:Outline 15833:Bibcode 15780:Bibcode 15696:Bibcode 15447:Bibcode 15374:Bibcode 15347:Bibcode 15223:Bibcode 15184:Bibcode 15079:Bibcode 15013:Bibcode 14972:Bibcode 14927:Bibcode 14890:Bibcode 14888:: 618, 14672:Bibcode 14603:Bibcode 14529:Bibcode 14487:Bibcode 13938:planets 13720:eclipse 13665:transit 13490:primary 13366:models. 13279:of the 13163:Jupiter 13149:in the 13103:due to 13072:primary 13017:primary 12868:Ptolemy 12850:planets 12779:substar 12757:natural 12626:system. 12562:spectra 12493:stellar 12421:planets 12310:gravity 12133:as the 11998:protons 11938:of the 11892:, five 11889:planets 11673:annular 11667:partial 11639:of the 11463:of the 11441:of the 11297:ellipse 11224:secular 11217:horizon 11042:opacity 10914:around 10858:In the 10811:primary 10769:primary 10764:in situ 10530:shadow. 10508:or the 10410:For an 10286:primary 10236:primary 10216:Mercury 10185:equator 10081:planemo 10028:planets 10004:stellar 9972:planets 9827:of all 9815:gravity 9811:rounded 9695:Jupiter 9646:of the 9637:orbital 9631:primary 9569:perigee 9553:primary 9383:if all 9380:primary 9296:secular 9285:Neptune 9199:primary 9037:(grey). 8965:primary 8861:occurs. 8852:opacity 8714:primary 8483:planets 8466:horizon 8323:at its 8202:horizon 8082:cluster 8039:azimuth 7923:moonlet 7799:moonlet 7697:of the 7506:meteors 7345:transit 7016:(MACHO) 6786:apsides 6747:is the 6573:L-point 6502:trojans 6440:ellipse 6310:in situ 6299:primary 6241:orbital 6214:or the 6094:Ptolemy 6071:Mercury 6035:in the 6033:Neptune 5954:(often 5812:to the 5763:horizon 5655:versus 5533:photons 5274:in the 5271:equator 5148:of the 5108:in the 5102:Jupiter 4989:Jupiter 4806:of the 4670:quasars 4562:of the 4525:of the 4472:planets 4385:in the 3954:Sample 3819:equator 3811:equinox 3803:equinox 3765:equator 3711:equator 3665:in the 3599:ellipse 3489:planets 3419:equator 3254:Antares 3242:evolved 3202:system. 3091:Neptune 2950:nebulae 2850:In the 2776:horizon 2644:of the 2626:or the 2596:protons 2287:Jupiter 2005:centaur 1905:natural 1899:planets 1882:motions 1803:equator 1574:baryons 1534:of the 1509:systems 1464:azimuth 1442:seasons 1397:in the 1300:density 1282:physics 1227:of the 1157:of the 1154:planets 837:Jupiter 825:in the 771:Jupiter 588:to its 582:body's 532:primary 517:In the 502:appulse 470:perigee 433:primary 373:Am star 215:parsecs 172:In the 16845:Botany 16719:Zodiac 16659:French 16364:Indian 16357:Hebrew 16096:Manner 15876: 15851: 15798: 15743: 15718:, A27. 15714: 15684:: 16, 15659: 15632: 15574: 15547: 15519:, NASA 15496:, NASA 15474: 15419: 15394: 15320: 15293: 15267: 15202: 15106: 15055: 15045: 14992: 14776: 14739: 14692: 14646: 14623: 14566: 14460: 14433: 14403: 14281:zodiac 14252:(ZAMS) 14234:zenith 14208:X-rays 14183:galaxy 13959:entire 13947:energy 13943:matter 13861:, and 13728:trojan 13611:, and 13584:planet 13516:galaxy 13346:planet 13210:syzygy 13196:aspect 13190:planet 12977:object 12910:galaxy 12885:(SMBH) 12855:Saturn 12793:fusion 12680:plasma 12449:merger 12443:galaxy 12427:comets 12328:helium 12306:plasma 12284:32.174 12035:comets 12023:aurora 12017:corona 12004:, and 11916:, and 11913:comets 11803:corona 11708:facula 11547:(SSSB) 11344:zenith 11242:, the 11149:galaxy 11109:RS CVn 11033:of an 10981:, and 10905:planet 10792:réseau 10583:X-rays 10555:. Its 10536:quasar 10427:pulsar 10370:planet 10103:planet 10061:, and 9981:, and 9943:planet 9889:planet 9883:planet 9848:planet 9793:planet 9768:, and 9756:. The 9590:apogee 9580:or an 9504:second 9466:parsec 9457:parsec 9333:orbits 9246:(e.g. 9202:. The 9190:of an 9091:of an 9025:. The 8911:planet 8905:object 8785:object 8702:comets 8610:minus 8363:helium 8334:nebula 8263:planet 8257:orbits 8196:zenith 8167:Quasar 8127:, and 7950:planet 7911:phases 7758:planet 7694:center 7641:galaxy 7543:helium 7468:meteor 7403:meteor 7385:comets 7357:zenith 7331:zenith 7257:period 7208:zenith 7083:planet 6983:waning 6977:waxing 6891:joules 6876:galaxy 6750:parsec 6582:bodies 6505:, and 6175:helium 6166:galaxy 6155:matter 6029:Uranus 6019:sulfur 6017:, and 6011:carbon 6007:oxygen 6003:helium 5964:. 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