Asteroid - Knowledge

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lower uncertainty than measurements of the reflected sunlight in the visible-light spectral region. If the two measurements can be combined, both the effective diameter and the geometric albedo—the latter being a measure of the brightness at zero phase angle, that is, when illumination comes from directly behind the observer—can be derived. In addition, thermal measurements at two or more wavelengths, plus the brightness in the visible-light region, give information on the thermal properties. The thermal inertia, which is a measure of how fast a material heats up or cools off, of most observed asteroids is lower than the bare-rock reference value but greater than that of the lunar regolith; this observation indicates the presence of an insulating layer of granular material on their surface. Moreover, there seems to be a trend, perhaps related to the gravitational environment, that smaller objects (with lower gravity) have a small regolith layer consisting of coarse grains, while larger objects have a thicker regolith layer consisting of fine grains. However, the detailed properties of this regolith layer are poorly known from remote observations. Moreover, the relation between thermal inertia and surface roughness is not straightforward, so one needs to interpret the thermal inertia with caution.

11149: 3294: 61: 15959: 11745: 16483: 917:. Sometimes asteroids were discovered and not seen again. So, starting in 1892, new asteroids were listed by the year and a capital letter indicating the order in which the asteroid's orbit was calculated and registered within that specific year. For example, the first two asteroids discovered in 1892 were labeled 1892A and 1892B. However, there were not enough letters in the alphabet for all of the asteroids discovered in 1893, so 1893Z was followed by 1893AA. A number of variations of these methods were tried, including designations that included year plus a Greek letter in 1914. A simple chronological numbering system was established in 1925. 2681: 3204: 1678: 2754: 70: 3359: 2102: 2864: 2464: 1699: 365: 16471: 2875: 41: 1070: 2830:

size. Light-curve measurements can also be made by GBO; when collected over a long period of time it allows an estimate of the rotational period, the pole orientation (sometimes), and a rough estimate of the asteroid's shape. Spectral data (both visible-light and near-infrared spectroscopy) gives information about the object's composition, used to classify the observed asteroids. Such observations are limited as they provide information about only the thin layer on the surface (up to several micrometers). As planetologist

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enough by the asteroid's gravity to allow an estimate of the asteroid's mass. The volume is then estimated using a model of the asteroid's shape. Mass and volume allow the derivation of the bulk density, whose uncertainty is usually dominated by the errors made on the volume estimate. The internal porosity of asteroids can be inferred by comparing their bulk density with that of their assumed meteorite analogues, dark asteroids seem to be more porous (>40%) than bright ones. The nature of this porosity is unclear.

1482: 16465: 11514: 3172: 747: 3144: 50: 2805: 1078: 11155: 895: 14320: 11739: 10934: 1378: 2813: 3158: 2269:, none of them have moons. The fact that such large asteroids as Sylvia may be rubble piles, presumably due to disruptive impacts, has important consequences for the formation of the Solar System: computer simulations of collisions involving solid bodies show them destroying each other as often as merging, but colliding rubble piles are more likely to merge. This means that the cores of the planets could have formed relatively quickly. 1498: 17627: 315: 3463:) cameras and computers directly connected to telescopes. As of 2011, it was estimated that 89% to 96% of near-Earth asteroids one kilometer or larger in diameter had been discovered. As of 29 October 2018, the LINEAR system alone had discovered 147,132 asteroids. Among the surveys, 19,266 near-Earth asteroids have been discovered including almost 900 more than 1 km (0.6 mi) in diameter. 17651: 15935: 3498: 945:). The formal naming convention uses parentheses around the number—e.g. (433) Eros—but dropping the parentheses is quite common. Informally, it is also common to drop the number altogether, or to drop it after the first mention when a name is repeated in running text. In addition, names can be proposed by the asteroid's discoverer, within guidelines established by the International Astronomical Union. 2649:, and was based on data collected from an eight-color asteroid survey performed in the 1980s. This resulted in 14 asteroid categories. In 2002, the Small Main-Belt Asteroid Spectroscopic Survey resulted in a modified version of the Tholen taxonomy with 24 different types. Both systems have three broad categories of C, S, and X asteroids, where X consists of mostly metallic asteroids, such as the 831: 17615: 15947: 16477: 1390: 17639: 8932: 8899: 8306: 4613: 3820: 3788: 3186: 615:

Mars 4 + 12 = 16. Now comes a gap in this so orderly progression. After Mars there follows a space of 4 + 24 = 28 parts, in which no planet has yet been seen. Can one believe that the Founder of the universe had left this space empty? Certainly not. From here we come to the distance of Jupiter by 4 + 48 = 52 parts, and finally to that of Saturn by 4 + 96 = 100 parts.

2257:, surface spectrum, and density. The last can only be determined accurately by observing the orbits of moons the asteroid might have. So far, every asteroid with moons has turned out to be a rubble pile, a loose conglomeration of rock and metal that may be half empty space by volume. The investigated asteroids are as large as 280 km in diameter, and include 2202:, but it may actually be a differentiated asteroid that was globally disrupted by an impact and then reassembled. Other asteroids appear to be the remnant cores or mantles of proto-planets, high in rock and metal. Most small asteroids are believed to be piles of rubble held together loosely by gravity, although the largest are probably solid. Some asteroids have 858:. A body in orbit around the Sun would move slightly between the pair of films. Under the stereoscope, the image of the body would seem to float slightly above the background of stars. Third, once a moving body was identified, its location would be measured precisely using a digitizing microscope. The location would be measured relative to known star locations. 1658:, where more asteroids than expected from such a curve are found. Most asteroids larger than approximately 120 km in diameter are primordial (surviving from the accretion epoch), whereas most smaller asteroids are products of fragmentation of primordial asteroids. The primordial population of the main belt was probably 200 times what it is today. 687:. Therefore I had no doubt of its being any other than a fixed star. The evening of the third, my suspicion was converted into certainty, being assured it was not a fixed star. Nevertheless before I made it known, I waited till the evening of the fourth, when I had the satisfaction to see it had moved at the same rate as on the preceding days. 876:, where computer programs determine whether an apparition ties together earlier apparitions into a single orbit. If so, the object receives a catalogue number and the observer of the first apparition with a calculated orbit is declared the discoverer, and granted the honor of naming the object subject to the approval of the 419:, was at first considered a new planet. It was followed by the discovery of other similar bodies, which with the equipment of the time appeared to be points of light like stars, showing little or no planetary disc, though readily distinguishable from stars due to their apparent motions. This prompted the astronomer Sir 9763: 1134:

Contrary to popular imagery, the asteroid belt is mostly empty. The asteroids are spread over such a large volume that reaching an asteroid without aiming carefully would be improbable. Nonetheless, hundreds of thousands of asteroids are currently known, and the total number ranges in the millions or

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This latter point seems in particular to follow from the astonishing relation which the known six planets observe in their distances from the Sun. Let the distance from the Sun to Saturn be taken as 100, then Mercury is separated by 4 such parts from the Sun. Venus is 4 + 3 = 7. The Earth 4 + 6 = 10.

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Strategies fall into two basic sets: fragmentation and delay. Fragmentation concentrates on rendering the impactor harmless by fragmenting it and scattering the fragments so that they miss the Earth or are small enough to burn up in the atmosphere. Delay exploits the fact that both the Earth and the

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bodies are called "objects" partly to avoid the need to classify them as asteroids or comets. They are thought to be predominantly comet-like in composition, though some may be more akin to asteroids. Most do not have the highly eccentric orbits associated with comets, and the ones so far discovered

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Asteroids and the asteroid belt are a staple of science fiction stories. Asteroids play several potential roles in science fiction: as places human beings might colonize, resources for extracting minerals, hazards encountered by spacecraft traveling between two other points, and as a threat to life

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The internal structure of asteroids is inferred only from indirect evidence: bulk densities measured by spacecraft, the orbits of natural satellites in the case of asteroid binaries, and the drift of an asteroid's orbit due to the Yarkovsky thermal effect. A spacecraft near an asteroid is perturbed

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of asteroids. Because there is no sufficiently large crater on the surface to be the source of that family, as there is on Vesta, it is thought that Hygiea may have been completely disrupted in the collision that formed the Hygiean family and recoalesced after losing a bit less than 2% of its mass.

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The concept of asteroid mining was proposed in 1970s. Matt Anderson defines successful asteroid mining as "the development of a mining program that is both financially self-sustaining and profitable to its investors". It has been suggested that asteroids might be used as a source of materials that

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Many asteroids have been placed in groups and families based on their orbital characteristics. Apart from the broadest divisions, it is customary to name a group of asteroids after the first member of that group to be discovered. Groups are relatively loose dynamical associations, whereas families

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Measurements of the rotation rates of large asteroids in the asteroid belt show that there is an upper limit. Very few asteroids with a diameter larger than 100 meters have a rotation period less than 2.2 hours. For asteroids rotating faster than approximately this rate, the inertial force at

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Daly, Luke; Lee, Martin R.; Hallis, Lydia J.; Ishii, Hope A.; Bradley, John P.; Bland, Phillip A.; Saxey, David W.; Fougerouse, Denis; Rickard, William D. A.; Forman, Lucy V.; Timms, Nicholas E.; Jourdan, Fred; Reddy, Steven M.; Salge, Tobias; Quadir, Zakaria; Christou, Evangelos; Cox, Morgan A.;

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Examination of the physical properties of the 41 largest and most massive main belt asteroids suggests that large asteroids without satellites are intact and their interiors have internal strength. This is consistent with results from the Dawn mission at both Vesta and Ceres. Ceres' volatile-rich

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is approximately 12,750 km in diameter and moves at approx. 30 km per second in its orbit, it travels a distance of one planetary diameter in about 425 seconds, or slightly over seven minutes. Delaying, or advancing the impactor's arrival by times of this magnitude can, depending on the

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As asteroids are rather small and faint objects, the data that can be obtained from ground-based observations (GBO) are limited. By means of ground-based optical telescopes the visual magnitude can be obtained; when converted into the absolute magnitude it gives a rough estimate of the asteroid's

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found Ceres near the predicted position and thus recovered it. At 2.8 AU from the Sun, Ceres appeared to fit the Titius–Bode law almost perfectly; however, Neptune, once discovered in 1846, was 8 AU closer than predicted, leading most astronomers to conclude that the law was a coincidence. Piazzi

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for guidance to the target. The warheads would be detonated 30 meters from the surface, deflecting or partially destroying the asteroid. Depending on the subsequent impacts on the course or the destruction of the asteroid, later missions would be modified or cancelled as needed. The "last-ditch"

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Various collision avoidance techniques have different trade-offs with respect to metrics such as overall performance, cost, failure risks, operations, and technology readiness. There are various methods for changing the course of an asteroid/comet. These can be differentiated by various types of

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Mid- to thermal-infrared observations, along with polarimetry measurements, are probably the only data that give some indication of actual physical properties. Measuring the heat flux of an asteroid at a single wavelength gives an estimate of the dimensions of the object; these measurements have

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detailed study of the formation of an active asteroid for the first time. Observations show that Dimorphos lost approximately 1 million kilograms after the collision. Impact produced a dust plume that temporarily brightened the Didymos system and developed a 10,000-kilometer (6,200 mi)-long

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spacecraft made it an active asteroid. Scientists had proposed that some active asteroids are the result of impact events, but no one had ever observed the activation of an asteroid. The DART mission activated Dimorphos under precisely known and carefully observed impact conditions, enabling the

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Originally, spectral designations were based on inferences of an asteroid's composition. However, the correspondence between spectral class and composition is not always very good, and a variety of classifications are in use. This has led to significant confusion. Although asteroids of different

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revealed that Ceres has a heavily cratered surface, but with fewer large craters than expected. Models based on the formation of the current asteroid belt had suggested Ceres should possess 10 to 15 craters larger than 400 km (250 mi) in diameter. The largest confirmed crater on Ceres,

981:). He introduced a disk (circle), a traditional symbol for a star, as the generic symbol for an asteroid. The circle was then numbered in order of discovery to indicate a specific asteroid. The numbered-circle convention was quickly adopted by astronomers, and the next asteroid to be discovered ( 708:

By this time, the apparent position of Ceres had changed (mostly due to Earth's motion around the Sun), and was too close to the Sun's glare for other astronomers to confirm Piazzi's observations. Toward the end of the year, Ceres should have been visible again, but after such a long time it was

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We include Trojans (bodies captured in Jupiter's 4th and 5th Lagrange points), Centaurs (bodies in orbit between Jupiter and Neptune), and trans-Neptunian objects (orbiting beyond Neptune) in our definition of "asteroid" as used on this site, even though they may more correctly be called "minor

537:, hypothesized to be the main reservoir of dormant comets. They inhabit the cold outer reaches of the Solar System where ices remain solid and comet-like bodies exhibit little cometary activity; if centaurs or trans-Neptunian objects were to venture close to the Sun, their volatile ices would 9408:

Marchis, Franck; Hestroffer, Daniel; Descamps, Pascal; Berthier, Jerome; Bouchez, Antonin H; Campbell, Randall D; Chin, Jason C. Y; van Dam, Marcos A; Hartman, Scott K; Johansson, Erik M; Lafon, Robert E; David Le Mignant; Imke de Pater; Stomski, Paul J; Summers, Doug M; Vachier, Frederic;

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that have lost their volatile surface materials, although having a faint or intermittent comet-like tail does not necessarily result in a classification as a near-Earth comet, making the boundaries somewhat fuzzy. The rest of the near-Earth asteroids are driven out of the asteroid belt by

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imaging can yield good information about asteroid shapes and orbital and rotational parameters, especially for near-Earth asteroids. Spacecraft flybys can provide much more data than any ground or space-based observations; sample-return missions gives insights about regolith composition.

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never officially defined, but can be informally used to mean "an irregularly shaped rocky body orbiting the Sun that does not qualify as a planet or a dwarf planet under the IAU definitions". The main difference between an asteroid and a comet is that a comet shows a coma (tail) due to

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of Milan and Bode in Berlin. He reported it as a comet but "since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet". In April, Piazzi sent his complete observations to Oriani, Bode, and French astronomer

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can react with the oxygen in the upper layer of the asteroids and create water. It has been estimated that "every cubic metre of irradiated rock could contain up to 20 litres"; study was conducted using an atom probe tomography, numbers are given for the Itokawa S-type asteroid.

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composition also is a likely contributor to both the absence of satellites at Ceres and of Ceres meteorites at Earth. These results suggest that collisional disruption creating rubble pile structure is a necessary condition for formation of satellites around main belt asteroids.

4585: 1588:, both with diameters of just over 500 km (300 mi). Vesta is the brightest of the four main-belt asteroids that can, on occasion, be visible to the naked eye. On some rare occasions, a near-Earth asteroid may briefly become visible without technical aid; see 1135:

more, depending on the lower size cutoff. Over 200 asteroids are known to be larger than 100 km, and a survey in the infrared wavelengths has shown that the asteroid belt has between 700,000 and 1.7 million asteroids with a diameter of 1 km or more. The

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asteroids, with albedos over 0.15 and densities greater than 2.7. Within these populations, larger asteroids are denser, presumably due to compression. There appears to be minimal macro-porosity (interstitial vacuum) in the score of asteroids with masses greater than

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kg, which is just 3% of the mass of the Moon; the mass of the Kuiper Belt and Scattered Disk is over 100 times as large. The four largest objects, Ceres, Vesta, Pallas, and Hygiea, account for maybe 62% of the belt's total mass, with 39% accounted for by Ceres alone.

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for stony (silicaceous) objects (17% of known asteroids) and U for those that did not fit into either C or S. This classification has since been expanded to include many other asteroid types. The number of types continues to grow as more asteroids are studied.

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observed more than 700 near-Earth asteroids. These observations determined rough sizes of the majority of observed objects, but provided limited detail about surface properties (such as regolith depth and composition, angle of repose, cohesion, and porosity).

8139:"The Asteroid Was Shooting Rocks Into Space. 'Were We Safe in Orbit?' – NASA's Osiris-Rex and Japan's Hayabusa2 spacecraft reached the space rocks they are surveying last year, and scientists from both teams announced early findings on Tuesday (03/19/2019)" 3108:

in September 2022 to assess the potential of a spacecraft impact to deflect an asteroid from a collision course with Earth. In October, NASA declared DART a success, confirming it had shortened Dimorphos' orbital period around Didymos by about 32 minutes.

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rocket, which did not make its first flight until after the report had been completed. Six Saturn V rockets would be used, each launched at variable intervals from months to hours away from impact. Each rocket was to be fitted with a single 100-megaton

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Acfer 049, a meteorite discovered in Algeria in 1990, was shown in 2019 to have an ultraporous lithology (UPL): porous texture that could be formed by removal of ice that filled these pores, this suggests that UPL "represent fossils of primordial ice".

1265:, one of the largest potentially hazardous asteroids with a diameter of 4.5 km (2.8 mi), has two moons measuring 100–300 m (330–980 ft) across, which were discovered by radar imaging during the asteroid's 2017 approach to Earth. 3231:, planned for launch in 2024, is intended study the results of the DART impact. It is expected to measure the size and morphology of the crater, and momentum transmitted by the impact, to determine the efficiency of the deflection produced by DART. 6824:

Marchi, S.; Ermakov, A. I.; Raymond, C. A.; Fu, R. R.; O'Brien, D. P.; Bland, M. T.; Ammannito, E.; De Sanctis, M. C.; Bowling, T.; Schenk, P.; Scully, J. E. C.; Buczkowski, D. L.; Williams, D. A.; Hiesinger, H.; Russell, C. T. (26 July 2016).

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All other objects (These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.), except satellites, orbiting the Sun shall be referred to collectively as "Small Solar System

3090:. In 2021, the probe departed the asteroid with a sample from its surface. Sample was delivered to Earth in September 2023. The spacecraft continues its extended mission, designated OSIRIS-APEX, to explore near-Earth asteroid Apophis in 2029. 2077:

the surface is greater than the gravitational force, so any loose surface material would be flung out. However, a solid object should be able to rotate much more rapidly. This suggests that most asteroids with a diameter over 100 meters are

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Both space and ground-based observatories conducted asteroid search programs; the space-based searches are expected to detect more objects because there is no atmosphere to interfere and because they can observe larger portions of the sky.

1777:, it rotates on its side, with its axis of rotation tilted at high angles to its orbital plane. Its composition is similar to that of Ceres: high in carbon and silicon, and perhaps partially differentiated. Pallas is the parent body of the 1430:, although it is not clear whether sufficient time was available for this to occur for Deimos. Capture also requires dissipation of energy. The current Martian atmosphere is too thin to capture a Phobos-sized object by atmospheric braking. 2503:

are tighter and result from the catastrophic break-up of a large parent asteroid sometime in the past. Families are more common and easier to identify within the main asteroid belt, but several small families have been reported among the

814:, whereas only slightly more than 300 had been discovered up to that point. It was known that there were many more, but most astronomers did not bother with them, some calling them "vermin of the skies", a phrase variously attributed to 809:

to detect asteroids, which appeared as short streaks on long-exposure photographic plates. This dramatically increased the rate of detection compared with earlier visual methods: Wolf alone discovered 248 asteroids, beginning with

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Matsumoto, Megumi; Tsuchiyama, Akira; Nakato, Aiko; Matsuno, Junya; Miyake, Akira; Kataoka, Akimasa; Ito, Motoo; Tomioka, Naotaka; Kodama, Yu; Uesugi, Kentaro; Takeuchi, Akihisa; Nakano, Tsukasa; Vaccaro, Epifanio (November 2019).

1115:(i.e. not very elongated) orbits. This belt is estimated to contain between 1.1 and 1.9 million asteroids larger than 1 km (0.6 mi) in diameter, and millions of smaller ones. These asteroids may be remnants of the 3470:

warned that the United States is unprepared for an asteroid impact event, and has developed and released the "National Near-Earth Object Preparedness Strategy Action Plan" to better prepare. According to expert testimony in the

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attributes such as the type of mitigation (deflection or fragmentation), energy source (kinetic, electromagnetic, gravitational, solar/thermal, or nuclear), and approach strategy (interception, rendezvous, or remote station).

2333:. The finding is unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids." 470:

of its near-surface ices by solar radiation. A few objects were first classified as minor planets but later showed evidence of cometary activity. Conversely, some (perhaps all) comets are eventually depleted of their surface

1452:. The high porosity of the interior of Phobos (based on the density of 1.88 g/cm, voids are estimated to comprise 25 to 35 percent of Phobos's volume) is inconsistent with an asteroidal origin. Observations of Phobos in the 2656:

The proportion of known asteroids falling into the various spectral types does not necessarily reflect the proportion of all asteroids that are of that type; some types are easier to detect than others, biasing the totals.

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almost 1000 km in diameter. A body is classified as a comet, not an asteroid, if it shows a coma (tail) when warmed by solar radiation, although recent observations suggest a continuum between these types of bodies.

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impactor are in orbit. An impact occurs when both reach the same point in space at the same time, or more correctly when some point on Earth's surface intersects the impactor's orbit when the impactor arrives. Since the

2186:(stony) compositions, respectively. The physical composition of asteroids is varied and in most cases poorly understood. Ceres appears to be composed of a rocky core covered by an icy mantle; Vesta is thought to have a 9363: 1426:, and hence a capture origin requires a mechanism for circularizing the initially highly eccentric orbit, and adjusting its inclination into the equatorial plane, most probably by a combination of atmospheric drag and 691:

Piazzi observed Ceres a total of 24 times, the final time on 11 February 1801, when illness interrupted his work. He announced his discovery on 24 January 1801 in letters to only two fellow astronomers, his compatriot

610:(now discredited). Except for an unexplained gap between Mars and Jupiter, Bode's formula seemed to predict the orbits of the known planets. He wrote the following explanation for the existence of a "missing planet": 2782:

Until the age of space travel, objects in the asteroid belt could only be observed with large telescopes, their shapes and terrain remaining a mystery. The best modern ground-based telescopes and the Earth-orbiting

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with Jupiter ejected over 99% of planetesimals in the belt. Simulations and a discontinuity in spin rate and spectral properties suggest that asteroids larger than approximately 120 km (75 mi) in diameter

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The first asteroids to be discovered were assigned iconic symbols like the ones traditionally used to designate the planets. By 1852 there were two dozen asteroid symbols, which often occurred in multiple variants.

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than the other asteroids, of around 3.32, and may possess a surface layer of ice. Like the planets, Ceres is differentiated: it has a crust, a mantle and a core. No meteorites from Ceres have been found on Earth.

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and other organic compounds, and some speculate that asteroid impacts may have seeded the early Earth with the chemicals necessary to initiate life, or may have even brought life itself to Earth (an event called

7732: 3652:(No. 110), discovered by M. Borelly at the Marseilles Observatory M. Borelly had previously discovered two planets bearing the numbers 91 and 99 in the system of asteroids revolving between Mars and Jupiter". 2518:

About 30–35% of the bodies in the asteroid belt belong to dynamical families, each thought to have a common origin in a past collision between asteroids. A family has also been associated with the plutoid

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at the Academy of Palermo, Sicily. Before receiving his invitation to join the group, Piazzi discovered Ceres on 1 January 1801. He was searching for "the 87th of the Catalogue of the Zodiacal stars of

985:, in 1852) was the first to be designated in that way at the time of its discovery. However, Psyche was given an iconic symbol as well, as were a few other asteroids discovered over the next few years. 1643:(3–4%), brings this figure up to a bit over 60%, whereas the next seven most-massive asteroids bring the total up to 70%. The number of asteroids increases rapidly as their individual masses decrease. 1464:

meteorites, again pointing away from an asteroidal origin. Both sets of findings support an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the

586:, is normally visible to the naked eye in dark skies when it is favorably positioned. Rarely, small asteroids passing close to Earth may be briefly visible to the naked eye. As of April 2022, the 191:. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to complete a full circuit of the Sun. 412:; this includes asteroids, comets, and more recently discovered classes. According to IAU, "the term 'minor planet' may still be used, but generally, 'Small Solar System Body' will be preferred." 13111: 2666:

spectral classifications are likely to be composed of different materials, there are no assurances that asteroids within the same taxonomic class are composed of the same (or similar) materials.

2303:, it may be getting replenished by a reservoir of ice under the surface. Organic compounds were also detected on the surface. The presence of ice on 24 Themis makes the initial theory plausible. 909:

decided that asteroids were being discovered at such a rapid rate that a different system was needed to categorize or name asteroids. In 1852, when de Gasparis discovered the twentieth asteroid,

2791:(variation in brightness during rotation) and their spectral properties. Sizes can be estimated by timing the lengths of star occultations (when an asteroid passes directly in front of a star). 8648: 6619: 6434:

Torppa, J.; Kaasalainen, M.; Michałowski, T.; Kwiatkowski, T.; Kryszczyńska, A.; Denchev, P.; Kowalski, R. (1996). "Shapes and rotational properties of thirty asteroids from photometric data".

2093:. However evidence suggests most of the color change occurs rapidly, in the first hundred thousand years, limiting the usefulness of spectral measurement for determining the age of asteroids. 1341:

have orbits strictly outside Earth's orbit: an Amor asteroid's perihelion distance (q) is greater than Earth's aphelion distance (1.017 AU). Amor asteroids are also near-earth objects so

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Descamps, P.; Marchis, F.; Berthier, J.; Emery, J.P.; Duchêne, G.; de Pater, I.; et al. (February 2011). "Triplicity and physical characteristics of asteroid (216) Kleopatra".

1200:(trailing Jupiter). More than a million Jupiter trojans larger than one kilometer are thought to exist, of which more than 7,000 are currently catalogued. In other planetary orbits only nine 2121:, one of the largest asteroids after the big four, reveal a similarly angular profile, suggesting it is also saturated with radius-size craters. Medium-sized asteroids such as Mathilde and 475:

and become asteroid-like. A further distinction is that comets typically have more eccentric orbits than most asteroids; highly eccentric asteroids are probably dormant or extinct comets.

8515: 1731:, appears nearly spherical although it may have an undifferentiated interior, like the majority of asteroids. The four largest asteroids constitute half the mass of the asteroid belt. 1085:

Various dynamical groups of asteroids have been discovered orbiting in the inner Solar System. Their orbits are perturbed by the gravity of other bodies in the Solar System and by the

1019:. It is thought that planetesimals in the asteroid belt evolved much like the rest of objects in the solar nebula until Jupiter neared its current mass, at which point excitation from 3648:: "Professor J. Watson has been awarded by the Paris Academy of Sciences, the astronomical prize, Lalande foundation, for the discovery of eight new asteroids in one year. The planet 2129:

covering the surface. Of the big four, Pallas and Hygiea are practically unknown. Vesta has compression fractures encircling a radius-size crater at its south pole but is otherwise a

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Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschlé, C. (1995). "Asteroid families: Search of a 12,487 asteroid sample using two different clustering techniques".

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It is unclear whether Martian moons Phobos and Deimos are captured asteroids or were formed due to impact event on Mars. Phobos and Deimos both have much in common with carbonaceous

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for the largest minor planets—those massive enough to have become ellipsoidal under their own gravity. Only the largest object in the asteroid belt has been placed in this category:

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during that early era, whereas smaller bodies are fragments from collisions between asteroids during or after the Jovian disruption. Ceres and Vesta grew large enough to melt and

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can only resolve a small amount of detail on the surfaces of the largest asteroids. Limited information about the shapes and compositions of asteroids can be inferred from their

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Aguiar, Jeffrey A.; Hattar, Khalid; Monterrosa, Anthony; Keller, Lindsay P.; Christoffersen, Roy; Dukes, Catherine A.; Loeffler, Mark J.; Thompson, Michelle S. (December 2021).

3344:). Some astrophysicists have suggested that if advanced extraterrestrial civilizations employed asteroid mining long ago, the hallmarks of these activities might be detectable. 865:, made up of the year of discovery, a letter representing the half-month of discovery, and finally a letter and a number indicating the discovery's sequential number (example: 14249: 13441: 9351: 2467:

A complex horseshoe orbit (the vertical looping is due to inclination of the smaller body's orbit to that of the Earth, and would be absent if both orbited in the same plane)

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The minor planets beyond Jupiter's orbit are sometimes also called "asteroids", especially in popular presentations. However, it is becoming increasingly common for the term

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for more than a year and took samples that were delivered to Earth in 2020. The spacecraft is now on an extended mission and expected to arrive at a new target in 2031.

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Morbidelli, Alessandro; Bottke, William F. Jr.; Froeschlé, Christiane; Michel, Patrick (January 2002). W. F. Bottke Jr.; A. Cellino; P. Paolicchi; R. P. Binzel (eds.).

3031:, finally landing on its surface in 2001. It was the first spacecraft to successfully orbit and land on an asteroid. From September to November 2005, the Japanese 559:

probe, are increasingly blurring the distinction between comets and asteroids, suggesting "a continuum between asteroids and comets" rather than a sharp dividing line.

2720: 647:"), asking that they combine their efforts and begin a methodical search for the expected planet. Although they did not discover Ceres, they later found the asteroids 482:

to be restricted to minor planets of the inner Solar System. Therefore, this article will restrict itself for the most part to the classical asteroids: objects of the

15633: 9984: 9283:

Didier Massonnet; Benoît Meyssignac (2006). "A captured asteroid : Our David's stone for shielding earth and providing the cheapest extraterrestrial material".

3933: 1562:. The three largest are very much like miniature planets: they are roughly spherical, have at least partly differentiated interiors, and are thought to be surviving 6268:

McFadden, Lucy A.; Skillman, David R.; Memarsadeghi, N (December 2018). "Dawn mission's search for satellites of Ceres: Intact protoplanets don't have satellites".

7212: 5483:

D.F. Lupishko; M. di Martino & T.A. Lupishko (September 2000). "What the physical properties of near-Earth asteroids tell us about sources of their origin?".

939:

of discovery and the sequence within that half-month. Once an asteroid's orbit has been confirmed, it is given a number, and later may also be given a name (e.g.

16407: 9105: 7181: 5458: 2847:; it provides information about the surface of the asteroid (for example can show the presence of craters and boulders). Such observations were conducted by the 6921: 1234:

Near-Earth asteroids, or NEAs, are asteroids that have orbits that pass close to that of Earth. Asteroids that actually cross Earth's orbital path are known as

16402: 11148: 10821: 2920: 79: 9636:(Report). Hearing before the Committee on Science, Space, and Technology. Vol. Part I and Part II. House of Representatives. 19 March 2013. p. 147. 6694: 3769: 1448:

Another hypothesis is that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a large

2625:. These properties are thought to correspond to the composition of the asteroid's surface material. The original classification system had three categories: 3662:, along with the definition "one of the recently-discovered planets." At this time it was common to anglicize the spellings of the names, e.g. "Aglaia" for 9386: 5983:

Schmidt, B.; Russell, C.T.; Bauer, J.M.; Li, J.; McFadden, L.A.; Mutchler, M.; et al. (2007). "Hubble Space Telescope Observations of 2 Pallas".

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that share many characteristics common to planets, and are atypical compared to the majority of irregularly shaped asteroids. The fourth-largest asteroid,

1294:

have orbits strictly inside Earth's orbit: an Atira asteroid's aphelion distance (Q) is smaller than Earth's perihelion distance (0.983 AU). That is,

2855:

in California (70 meter dish). Radar observations can also be used for accurate determination of the orbital and rotational dynamics of observed objects.

590:

had data on 1,199,224 minor planets in the inner and outer Solar System, of which about 614,690 had enough information to be given numbered designations.

16097: 9760: 8967: 7559: 1754:, and so is devoid of water; its composition is mainly of basaltic rock with minerals such as olivine. Aside from the large crater at its southern pole, 766:) were discovered by von Zach's group over the next few years, with Vesta found in 1807. No new asteroids were discovered until 1845. Amateur astronomer 7536: 6342: 14207: 13544: 8617: 6570: 1043:

are captured in the outer asteroid belt, at distances greater than 2.6 AU. Most were later ejected by Jupiter, but those that remained may be the

4854: 10854: 9637: 5595: 3723:

The definition in the 1995 paper (Beech and Steel) has been updated by a 2010 paper (Rubin and Grossman) and the discovery of 1 meter asteroids.

578:

Despite their large numbers, asteroids are a relatively recent discovery, with the first one—Ceres—only being identified in 1801. Only one asteroid,

5668: 3635:

In an oral presentation, Clifford Cunningham presented his finding that the word was coined by Charles Burney, Jr., the son of a friend of Herschel.

15869: 9865: 6513: 675:", but found that "it was preceded by another". Instead of a star, Piazzi had found a moving star-like object, which he first thought was a comet: 9326: 6771: 6131: 11886: 7646: 6477:

Larson, H.P.; Feierberg, M.A. & Lebofsky, L.A. (1983). "The composition of asteroid 2 Pallas and its relation to primitive meteorites".

6243: 2117:

is a rubble pile saturated with craters with diameters the size of the asteroid's radius. Earth-based observations of 300 km (190 mi)

721:. In a few weeks, he predicted the path of Ceres and sent his results to von Zach. On 31 December 1801, von Zach and fellow celestial policeman 7860: 2113:" (Ceres, Pallas, Vesta, and Hygiea), asteroids are likely to be broadly similar in appearance, if irregular in shape. 50 km (31 mi) 8582: 7305:; Zakharov, Vladimir; Lee, Seungwon; von Allmen, Paul; et al. (2014). "Localized sources of water vapour on the dwarf planet (1) Ceres". 5007:

Bottke, William F. Jr.; Durda, Daniel D.; Nesvorny, David; Jedicke, Robert; Morbidelli, Alessandro; Vokrouhlicky, David; Levison, Hal (2005).

4652: 1349:. (This implies that the asteroid's semi-major axis (a) is also larger than 1.017 AU.) Some Amor asteroid orbits cross the orbit of Mars. 17400: 16374: 15421: 7885: 5930: 5327: 2622: 2283:

Scientists hypothesize that some of the first water brought to Earth was delivered by asteroid impacts after the collision that produced the

1220:

is also known. Numerical orbital dynamics stability simulations indicate that Saturn and Uranus probably do not have any primordial trojans.

9261: 778:

was given the honor of naming the asteroid. After this, other astronomers joined; 15 asteroids were found by the end of 1851. In 1868, when

7453: 3861: 850:. Pairs of photographs were taken, typically one hour apart. Multiple pairs could be taken over a series of days. Second, the two films or 1165:

Trojans are populations that share an orbit with a larger planet or moon, but do not collide with it because they orbit in one of the two

17415: 17123: 16895: 15566: 14005: 8873: 4773: 4622: 12382: 9079: 4955: 17234: 16927: 12065: 10869: 10283: 10251: 7287: 3590: 2221:

In the main asteroid belt, there appear to be two primary populations of asteroid: a dark, volatile-rich population, consisting of the

14387: 8847: 8514:

Li, Jian-Yang; Hirabayashi, Masatoshi; Farnham, Tony; Knight, Matthew; Tancredi, Gonzalo; Moreno, Fernando; et al. (March 2022).

4152: 2746:

revealed that it had six comet-like tails. The tails are suspected to be streams of material ejected by the asteroid as a result of a

1261:). As of October 2021, there were 85 NEAs known to have at least one moon, including three known to have two moons. The asteroid 15332: 8288: 4454: 3437: 2441:

Asteroids are commonly categorized according to two criteria: the characteristics of their orbits, and features of their reflectance

290: 8941: 4569: 320:

A composite image, to the same scale, of the asteroids imaged at high resolution prior to 2012. They are, from largest to smallest:

17435: 14227: 10320: 10298: 8112: 7019: 3904: 770:

started his searches of new asteroids in 1830, and fifteen years later, while looking for Vesta, he found the asteroid later named

9409:

Wizinovich, Peter L; Wong, Michael H (2011). "Extrasolar Asteroid Mining as Forensic Evidence for Extraterrestrial Intelligence".

8232:

Jewitt, D.; Agarwal, J.; Weaver, H.; Mutchler, M.; Larson, S. (2013). "The Extraordinary Multi-Tailed Main-Belt Comet P/2013 P5".

6645: 17065: 16090: 11818: 4480: 3467: 3097:(DART), a mission to test technology for defending Earth against potential hazardous objects. DART deliberately crashed into the 1238:. As of April 2022, a total of 28,772 near-Earth asteroids were known; 878 have a diameter of one kilometer or larger. 9222: 7584:

Callahan, M.P.; Smith, K.E.; Cleaves, H.J.; Ruzica, J.; Stern, J.C.; Glavin, D.P.; House, C.H.; Dworkin, J.P. (11 August 2011).

4824: 4546: 4094: 3941: 155:). The size and shape of asteroids vary significantly, ranging from small rubble piles under a kilometer across and larger than 16957: 16789: 15487: 15132: 15117: 15097: 14409: 14356: 10475: 10460: 10383: 10059:; Sykes, Mark V.; Stern, Alan; Runyon, Kirby (February 2019). "The Reclassification of Asteroids from Planets to Non-Planets". 5739:; Dobrovolskis, Anthony R.; Lago, Bernard (1980). "Orbital history of the Martian satellites with inferences on their origin". 5039: 3401:

had been discovered as long ago as 1898, and the 1930s brought a flurry of similar objects. In order of discovery, these were:

802: 14405: 14390: 12362: 8699: 4175: 1418:

very similar to those of C- or D-type asteroids. Based on their similarity, one hypothesis is that both moons may be captured

989:

was the first asteroid that was not assigned an iconic symbol, and no iconic symbols were created after the 1855 discovery of

17526: 17521: 17247: 15431: 15164: 15127: 15122: 14399: 10525: 10470: 10465: 10141: 10122: 10046: 10024: 9996: 9966: 9947: 8098: 8001: 6021: 5069: 4579: 4448: 4345: 4260: 4070: 4027: 2110: 2071: 2067: 285:

Near-Earth asteroids have the potential for catastrophic consequences if they strike Earth, with a notable example being the

8192: 6743: 4266: 17586: 17455: 17410: 17239: 15857: 15794: 15448: 15169: 15107: 15102: 14398: 13978: 12950: 12442: 11929: 11421: 11021: 10420: 10388: 10278: 3353: 921: 862: 14396: 14393: 14389: 14385: 7360: 5837: 5541: 4683: 17475: 16011: 15112: 13864: 13374: 13010: 10430: 10223: 9529: 2867: 2266: 14403: 14395: 6183:

Parker, J.W.; Stern, S.A.; Thomas, P.C.; Festou, M.C.; Merline, W.J.; Young, E.F.; Binzel, R.P.; Lebofsky, L.A. (2002).

5085:

McKinnon, William; McKinnon, B. (2008). "On The Possibility of Large KBOs Being Injected into The Outer Asteroid Belt".

2417:, suggesting that chemical processes on asteroids can produce some fundamentally essential bio-ingredients important to 722: 16083: 14392: 10545: 7204: 5724: 17506: 14410: 14406: 11876: 10656: 7173: 3293: 1801:

imager in 2017 and 2018, revealed that Hygiea has a nearly spherical shape, which is consistent both with it being in

1081:

A map of planets and asteroid groups of the inner solar system. Distances from sun are to scale, object sizes are not.

861:

These first three steps do not constitute asteroid discovery: the observer has only found an apparition, which gets a

17581: 16383: 16367: 16214: 15260: 15233: 14401: 14266: 13458: 12537: 11960: 11513: 11388: 10874: 10482: 7119:; Kelley, M.S.; Licandro, J.; et al. (2010). "Water ice and organics on the surface of the asteroid 24 Themis". 7043:

P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis.

3459:

All of these considerations helped spur the launch of highly efficient surveys, consisting of charge-coupled device (

2924: 795: 6016:. Practical Astronomy Handbooks. Vol. 1. Translated by Dunlop, Storm. Cambridge University Press. p. 297. 5431: 1646:

The number of asteroids decreases markedly with increasing size. Although the size distribution generally follows a

194:

Asteroids have historically been observed from Earth. The first close-up observation of an asteroid was made by the

17299: 16732: 16649: 15648: 14411: 11676: 11535: 11237: 6698: 6185:"Analysis of the First Disk-resolved Images of Ceres from Ultraviolet Observations with the Hubble Space Telescope" 4198: 3501: 3094: 2766: 1127:

into planets during the formative period of the Solar System was prevented by large gravitational perturbations by

973: 877: 389: 294: 8909: 3746: 3340:

perspective, asteroid prospecting could provide scientific data for the search for extraterrestrial intelligence (

2878:

Asteroid 6481 Tenzing, center, is seen moving against a background of stars in this series of images taken by the

1784:

Hygiea is the largest carbonaceous asteroid and, unlike the other largest asteroids, lies relatively close to the

1566:. The vast majority, however, are much smaller and are irregularly shaped; they are thought to be either battered 17116: 16962: 16902: 16578: 14254: 13916: 13478: 13446: 12920: 12212: 11871: 10983: 9603: 7949:

Bus, S.J. (2002). "Phase II of the Small Main-belt Asteroid Spectroscopy Survey: A feature-based taxonomy".

7881: 4119: 2723:, but this name implies they are necessarily icy in composition like a comet and that they only exist within the 2618: 735: 15176: 9378: 9227:

Space Resources and Space Settlements, 1977 Summer Study at NASA Ames Research Center, Moffett Field, California

4379: 3797: 16851: 16146: 15827: 15243: 15077: 14197: 13797: 13483: 13364: 12940: 12890: 12427: 11881: 11222: 10900: 6886:"The geology of the Kerwan quadrangle of dwarf planet Ceres: Investigating Ceres' oldest, largest impact basin" 3600: 3488: 3306:. Materials that are heavy and expensive to launch from Earth may someday be mined from asteroids and used for 2300: 1743: 538: 501:

in 1801, all known asteroids spent most of their time at or within the orbit of Jupiter, though a few, such as

6720: 3479:

would require at least five years of preparation before a mission to intercept an asteroid could be launched.

17028: 16305: 15352: 15248: 14276: 13404: 13184: 13169: 12492: 11808: 10836: 10246: 8990: 7544: 6334: 5955: 3585: 3288: 1684: 15765: 9630: 6770:

Conrad, A.R.; Dumas, C.; Merline, W.J.; Drummonf, J.D.; Campbell, R.D.; Goodrich, R.W.; et al. (2007).

6571:"A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea, Supplementary Information" 17496: 17420: 17196: 16360: 15852: 15407: 15387: 15282: 14202: 14086: 13493: 13339: 12522: 12312: 12302: 10268: 6569:

Vernazza, P.; Jorda, L.; Ševeček, P.; Brož, M.; Viikinkoski, M.; Hanuš, J.; et al. (28 October 2019).

5881: 5232:(2018). "Masses of the Main Asteroid Belt and the Kuiper Belt from the Motions of Planets and Spacecraft". 4880: 3964: 3317:

on Earth becomes more real, the idea of extracting valuable elements from asteroids and returning these to

1812:, as satellites of main belt asteroids are mostly believed to form from collisional disruption, creating a 798:, the three most successful asteroid-hunters at that time, on a commemorative medallion marking the event. 15770: 14408: 7888:(1975). "Surface properties of asteroids: A synthesis of polarimetry, radiometry, and spectrophotometry". 7302: 6885: 6239: 5863:

Abstracts of the 25th Annual Lunar and Planetary Science Conference, held in Houston, TX, 14–18 March 1994

5678: 4977: 2738:

and Guido Pizarro in 1996 and given the cometary designation 133P/Elst-Pizarro. Another notable object is

2306:

In October 2013, water was detected on an extrasolar body for the first time, on an asteroid orbiting the

1229: 16598: 16131: 15927: 15453: 15382: 15347: 14386: 14380: 13349: 11893: 11803: 10846: 10514: 9891: 9816: 9196: 2296: 1056: 1002: 15367: 10905: 8138: 6544: 17605: 17465: 17440: 17109: 16295: 16285: 15842: 15643: 15526: 15509: 15475: 14407: 14349: 14212: 14076: 13519: 13379: 13041: 13015: 12975: 12970: 12816: 12660: 12625: 12615: 11924: 11791: 11781: 11776: 10196: 9352:"Evidence of asteroid mining in our galaxy may lead to the discovery of extraterrestrial civilizations" 8799: 8774: 8749: 8724: 8673: 7788: 7701: 6802: 6139: 6037:

Bottkejr, W; Durda, D; Nesvorny, D; Jedicke, R; Morbidelli, A; Vokrouhlicky, D; Levison, H (May 2005).

4220: 2879: 2330: 1460:, which are well known from the surface of Mars. The spectra are distinct from those of all classes of 906: 787: 783: 60: 11738: 11003: 8492: 8168:. Space Telescope Science Institute (STScI), official YouTube channel for the Hubble Space Telescope. 7650: 7234:

Rivkin, Andrew S.; Emery, Joshua P. (2010). "Detection of ice and organics on an asteroidal surface".

6721:"University of Hawaii astronomer and colleagues find evidence that asteroids change color as they age" 3456:, had detected hundreds of upper-atmosphere impacts by objects ranging from one to ten meters across. 2911:

with six comet-like tails, and observing asteroids that were chosen as targets of dedicated missions.

17516: 17341: 17212: 17132: 16932: 16588: 16290: 15685: 15660: 15470: 14190: 14185: 14180: 13684: 13629: 13005: 12527: 12437: 12332: 11813: 10315: 10263: 10178: 7849: 4123: 3505: 3492: 3453: 3256: 2843:

Near-Earth asteroids that come into close vicinity of the planet can be studied in more details with

1751: 1060: 1029: 672: 393: 20: 16482: 14404: 11744: 9836: 5700: 4954:. U.S. Naval Observatory. Washington, DC: Naval Meteorology and Oceanography Command. Archived from 4731:"Address of the Retiring President of the Society in Awarding the Bruce Medal to Professor Max Wolf" 2680: 1510: 509:, astronomers discovered small bodies that permanently resided further out than Jupiter, now called 17460: 17278: 16967: 16727: 16524: 16126: 15976: 15581: 13946: 13133: 13121: 12960: 12517: 12417: 12392: 12287: 12262: 12130: 11975: 11196: 10783: 9631:

Threats from Space: A review of U.S. Government efforts to track and mitigate asteroids and meteors

9325:. Keck Institute for Space Studies, California Institute of Technology, Jet Propulsion Laboratory. 9319: 8234: 6943: 6772:"Direct measurement of the size, shape, and pole of 511 Davida with Keck AO in a single night" 6364:

Russel, C.; Raymond, C.; Fraschetti, T.; Rayman, M.; Polanskey, C.; Schimmels, K.; Joy, S. (2005).

5919: 4660: 3445: 3203: 2907:, such as tracking the colliding asteroids in the main belt, break-up of an asteroid, observing an 2568:

for a few decades or a few hundred years, before returning to their earlier status. Both Earth and

1580:

is by far the largest asteroid, with a diameter of 940 km (580 mi). The next largest are

1442: 1407: 1120: 1025: 16352: 10553: 8218: 7288:"Watery Asteroid Discovered in Dying Star Points to Habitable Exoplanets – W. M. Keck Observatory" 5875:

Andert, Thomas P.; Rosenblatt, Pascal; Pätzold, Martin; Häusler, Bernd; et al. (7 May 2010).

5374: 4799: 1445:

in orbit after Mars formed, rather than forming concurrently out of the same birth cloud as Mars.

434: 171:

Of the roughly one million known asteroids, the greatest number are located between the orbits of

17217: 17072: 17050: 16987: 16514: 16310: 16194: 16106: 15665: 15492: 15139: 15043: 14956: 14656: 14506: 14397: 14388: 14148: 13719: 12765: 12670: 12552: 12462: 12447: 12372: 12272: 12143: 12060: 11903: 11766: 11761: 11350: 10664: 10536: 10338: 10216: 9359: 9257: 9253: 8824: 8169: 7672: 6078:"The Origin and Evolution of the Asteroid Belt – Implications for Vesta and Ceres" 6038: 5204: 3854: 3623: 3529:" was one of the first projects designed in 1967 as a contingency plan in case of collision with 3358: 3322: 3045:

of its surface to Earth on 13 June 2010, the first asteroid sample-return mission. In 2007,

2896: 2592: 1802: 1677: 1558:

for the largest down to rocks just 1 meter across, below which an object is classified as a

1465: 1160: 731: 472: 11566: 3566:

on Earth or other inhabited planets, dwarf planets, and natural satellites by potential impact.

17681: 17576: 17156: 17060: 16231: 15670: 15608: 15556: 15546: 15531: 15482: 15342: 15272: 14694: 14382: 14217: 14175: 14113: 13802: 13699: 13694: 13514: 13416: 13389: 12965: 12635: 12557: 12347: 11355: 9831: 6950:(Press release). News Center / Release Images. Space Telescope Science Institute. 19 April 1995 4902: 4708:. Address at the semi-centennial of the Dearborn Observatory. Vol. 24. pp. 550–558 . 3472: 3441: 2904: 2784: 2743: 2326: 2199: 2101: 1069: 522: 510: 15591: 14402: 14394: 14391: 9817:"Gravitational Effects of Earth in Optimizing Delta-V for Deflecting Earth-Crossing Asteroids" 9068: 6011: 4777: 4630: 4019: 4013: 3989: 3374:'s, and that could, given enough time, collide with Earth. The three most important groups of 2753: 838:

In the past, asteroids were discovered by a four-step process. First, a region of the sky was

128: 17671: 17380: 16942: 16758: 16613: 16136: 16036: 15963: 15837: 15690: 15653: 15541: 15536: 14342: 14143: 14108: 13837: 13779: 13729: 13709: 13589: 13067: 12945: 12822: 12740: 12675: 12477: 12432: 12247: 12079: 12040: 11970: 11945: 11381: 11345: 11134: 10859: 10273: 9220: 8064: 6831: 3580: 3547: 3543: 3460: 3042: 3033: 2985: 2852: 2731: 2727:, whereas the growing population of active asteroids shows that this is not always the case. 2638: 2314: 1785: 1064: 554: 530: 15705: 10166: 9722: 9462: 8090: 3264: 2214:

are thought to be the results of collisions that disrupted a parent asteroid, or possibly a

17501: 17364: 17294: 17043: 17033: 16864: 16844: 16783: 16672: 16644: 16618: 16608: 16204: 15598: 15551: 15208: 14666: 14631: 14626: 14520: 14471: 14444: 14400: 14379: 14069: 13911: 13852: 13822: 13644: 13634: 13549: 13436: 13304: 12665: 12402: 12192: 11786: 11669: 11540: 11227: 11217: 11181: 10992: 10895: 10455: 10078: 9927: 9921: 9797: 9734: 9675: 9574: 9428: 9292: 9120: 8632: 8540: 8419: 8346: 8253: 8078: 7958: 7931: 7897: 7822: 7741: 7599: 7492: 7396: 7314: 7245: 7130: 7076: 6995: 6897: 6840: 6786: 6585: 6528: 6486: 6443: 6414: 6377: 6277: 6206: 6089: 6050: 5992: 5890: 5790: 5748: 5614: 5510: 5492: 5442: 5342: 5298: 5251: 5175: 5094: 5023: 4918: 4742: 4709: 4522: 4436: 4425: 4391: 4160: 3829: 3560: 3227: 3171: 3143: 3131: 3060: 2998: 2959: 2642: 2322: 1904: 1855: 1794: 1735: 1712: 1688: 1620: 1577: 1112: 954: 822:. Even a century later, only a few thousand asteroids were identified, numbered and named. 775: 710: 643:(Monthly Correspondence), sent requests to 24 experienced astronomers (whom he dubbed the " 636: 603: 567: 498: 416: 374: 195: 160: 95: 14383: 14381: 10158: 3329:, becomes more attractive. Hypothetically, water processed from ice could refuel orbiting 1805:, or formerly being in hydrostatic equilibrium, or with being disrupted and recoalescing. 8: 17655: 17405: 17371: 17284: 16937: 16883: 16877: 16857: 16837: 16711: 16561: 16551: 16504: 16451: 16050: 15939: 15777: 15750: 15700: 15504: 14968: 14661: 14513: 14288: 14042: 14032: 14027: 13988: 13968: 13936: 13931: 13926: 13879: 13847: 13769: 13759: 13739: 13724: 13714: 13704: 13659: 13614: 13559: 13534: 13524: 13344: 13334: 13289: 13284: 13279: 13274: 13254: 13238: 13228: 13223: 13218: 13213: 12895: 12452: 12217: 12074: 12050: 12045: 12025: 11980: 11850: 11242: 10976: 8945: 8053: 6970: 3375: 3307: 3214: 2874: 2848: 2817: 2757:

Dimorphos and the tail created after the DART impact, photo by the Hubble Space Telescope

1419: 1116: 1032:, with heavy metallic elements sinking to the core, leaving rocky minerals in the crust. 873: 718: 698: 607: 587: 274: 16470: 14864: 14743: 12357: 10082: 9931: 9801: 9738: 9679: 9578: 9484: 9432: 9296: 9169: 9124: 8636: 8561: 8544: 8423: 8375: 8350: 8324: 8257: 8082: 7962: 7935: 7901: 7826: 7745: 7603: 7496: 7400: 7318: 7249: 7134: 7080: 6999: 6901: 6844: 6790: 6589: 6532: 6490: 6447: 6419: 6381: 6281: 6211: 6161: 6093: 6054: 5996: 5920:"Compositional Interpretation of PFS/MEx and TES/MGS Thermal Infrared Spectra of Phobos" 5894: 5794: 5752: 5654:

Burns, Joseph A. (1992). "Contradictory Clues as to the Origin of the Martian Moons" in

5618: 5496: 5446: 5346: 5302: 5255: 5179: 5098: 5027: 4923: 4747: 4714: 4526: 4440: 4395: 3910: 3526: 3207:

Asteroids and comets visited by spacecraft as of 2019 (except Ceres and Vesta), to scale

2463: 1698: 553:. Other recent observations, such as the analysis of the cometary dust collected by the 364: 17676: 17643: 17631: 16997: 16977: 16831: 16437: 16030: 15900: 15847: 15725: 15695: 15603: 15416: 14553: 14384: 14059: 13993: 13983: 13961: 13956: 13951: 13874: 13832: 13807: 13749: 13669: 13649: 13564: 13554: 13488: 13473: 12780: 12680: 12422: 12055: 12030: 12020: 12010: 11990: 11950: 11622: 11322: 11271: 10937: 10209: 10094: 10068: 9857: 9608: 9444: 9418: 9136: 9042: 8574: 8530: 8443: 8388: 8336: 8269: 8243: 8143: 8104: 8068: 7974: 7764: 7727: 7622: 7585: 7513: 7480: 7428: 7338: 7269: 7154: 7092: 7066: 7011: 6985: 6913: 6861: 6826: 6611: 6459: 6293: 6196: 6113: 5918:

Giuranna, Marco; Roush, Ted L.; Duxbury, Thomas; Hogan, Robert C.; et al. (2010).

5813: 5778: 5632: 5604: 5366: 5267: 5241: 4701: 4538: 4289: 3449: 3429: 3314: 2969:. Other asteroids briefly visited by spacecraft en route to other destinations include 2863: 2707:, or other visual evidence of mass-loss (like a comet), but their orbit remains within 2598: 2508: 2495: 1431: 1324:

have a semi-major axis of more than 1 AU and cross Earth's orbit. Mathematically,

1307:

have a semi-major axis of less than 1 AU and cross Earth's orbit. Mathematically,

1136: 968: 851: 779: 767: 684: 619:

Bode's formula predicted another planet would be found with an orbital radius near 2.8

14837: 14800: 14165: 13599: 8265: 6455: 5143:. NASA JPL. Search for asteroids in the main belt regions with a diameter >100 4087: 2299:. The surface of the asteroid appears completely covered in ice. As this ice layer is 1750:

Vesta, too, has a differentiated interior, though it formed inside the Solar System's

623:(AU), or 420 million km, from the Sun. The Titius–Bode law got a boost with 17391: 17271: 17227: 17191: 17171: 17055: 16814: 16634: 16443: 16189: 16141: 15890: 15460: 15402: 15193: 15082: 15008: 14949: 14678: 14283: 14081: 13904: 13899: 13754: 13639: 13431: 13421: 13394: 13369: 13203: 13127: 13057: 12700: 12685: 12162: 12102: 12005: 12000: 11955: 11753: 11643: 11594: 11478: 11452: 11314: 11288: 11247: 11042: 10864: 10395: 10293: 10137: 10118: 10110: 10098: 10056: 10042: 10020: 10010: 10006: 9992: 9976: 9962: 9943: 9861: 9683: 9663: 9448: 9140: 9046: 9034: 9016: 8578: 8566: 8447: 8435: 8407: 8392: 8380: 8362: 8323:

Li, Jian-Yang; Hirabayashi, Masatoshi; Farnham, Tony L.; et al. (1 March 2023).

8108: 8094: 7997: 7909: 7769: 7627: 7518: 7432: 7420: 7412: 7384: 7330: 7261: 7146: 7096: 6866: 6615: 6498: 6463: 6297: 6117: 6105: 6077: 6017: 5818: 5760: 5636: 5358: 5271: 5065: 5058: 5008: 4832: 4575: 4542: 4510: 4472: 4444: 4256: 4066: 4023: 4009: 4005: 3595: 3418: 3394: 3114: 3098: 3050: 2955: 2557: 2512: 2391: 2159: 2137: 1833: 1809: 1667: 1258: 1254: 1103:

The majority of known asteroids orbit within the asteroid belt between the orbits of

1020: 791: 714: 620: 599: 491: 409: 337: 260: 218: 180: 14920: 12317: 9304: 9230: 8273: 7015: 6917: 5779:"Origin of Phobos and Deimos by the impact of a Vesta-to-Ceres sized body with Mars" 5531: 5370: 5117: 4774:"Carolyn Shoemaker, planetary astronomer and most successful 'comet hunter' to date" 17619: 17166: 17018: 16315: 15951: 15755: 15745: 15638: 15613: 15023: 14993: 14844: 14718: 14558: 14423: 14242: 14237: 14232: 14222: 14096: 14091: 13973: 13764: 13664: 13604: 13584: 13574: 13539: 13509: 13036: 12172: 12097: 11985: 11866: 11834: 11830: 11494: 11457: 11447: 11437: 11374: 11328: 11087: 11077: 11062: 11057: 11008: 10831: 10086: 10034: 9935: 9849: 9841: 9742: 9582: 9565: 9436: 9300: 9128: 9026: 9021: 8640: 8556: 8548: 8427: 8370: 8354: 8261: 8086: 7978: 7966: 7905: 7877: 7830: 7759: 7749: 7617: 7607: 7508: 7500: 7404: 7342: 7322: 7273: 7253: 7236: 7158: 7138: 7121: 7084: 7003: 6905: 6856: 6848: 6794: 6601: 6593: 6536: 6494: 6451: 6385: 6285: 6216: 6097: 6058: 5898: 5808: 5798: 5756: 5622: 5450: 5350: 5306: 5259: 5229: 5183: 5031: 4928: 4752: 4530: 4058: 3330: 3127: 2735: 2614: 2576: 2442: 2278: 2215: 2090: 1778: 1453: 1423: 1166: 1139:

of most of the known asteroids are between 11 and 19, with the median at about 16.

1086: 839: 806: 644: 624: 420: 286: 69: 9132: 6315: 5719:

Landis, Geoffrey A.; "Origin of Martian Moons from Binary Asteroid Dissociation",

4341: 4062: 3428:

Two events in later decades increased the alarm: the increasing acceptance of the

3274:. The spacecraft is tasked with collecting samples of the regolith of Kamo'oalewa. 2734:. It was discovered (as an asteroid) in 1979 but then was found to have a tail by 1506: 889: 264:, launched in 2021, is tasked with studying ten different asteroids, two from the 17542: 17491: 17222: 17023: 16541: 16464: 16236: 16179: 16164: 15822: 15720: 15628: 15519: 15497: 15294: 15238: 15228: 15018: 14998: 14973: 14961: 14915: 14903: 14807: 14790: 14750: 14728: 14723: 14323: 14293: 13889: 13774: 13529: 12467: 12457: 12126: 11965: 11796: 11708: 11662: 11232: 11102: 11097: 11072: 11067: 11037: 10826: 10793: 10788: 10778: 10773: 10752: 10747: 10723: 10718: 10713: 10708: 10703: 10698: 10693: 10674: 10669: 10644: 10639: 10634: 10629: 10624: 10619: 10614: 10600: 10595: 10590: 10585: 10580: 10573: 10568: 10563: 10558: 10519: 10447: 10410: 10305: 10288: 10090: 10014: 9785: 9767: 9704: 9587: 9560: 9556: 8196: 7923: 7088: 6909: 6798: 6289: 6062: 5035: 4948: 4250: 4179: 3539: 3379: 3366:, small asteroids roughly 1 to 20 meters in diameter impacting Earth's atmosphere 3284: 3268: 2908: 2700: 2675: 2650: 2646: 2630: 2626: 2565: 2530: 2458: 2238: 2234: 2226: 2222: 2211: 2207: 2194:

mantle, and basaltic crust. Thought to be the largest undifferentiated asteroid,

2171: 2167: 2163: 2147: 2143: 1808:

Internal differentiation of large asteroids is possibly related to their lack of

1763: 1457: 1435: 1403: 1320: 1269: 1044: 663: 461:, with anything smaller than one meter across being called a meteoroid. The term 148: 140: 132: 17092:

Probes are listed in chronological order of launch. indicates mission failures.

16699: 16694: 16689: 12630: 10948: 9530:"America isn't ready to handle a catastrophic asteroid impact, new report warns" 8470:"SOAR Telescope Catches Dimorphos's Expanding Comet-like Tail After DART Impact" 6405:

Burbine, T.H. (July 1994). "Where are the olivine asteroids in the main belt?".

6322:(Press release). Space Telescope Science Institute. 19 April 1995. STScI-1995-20 2552:. The first instance of this type of orbital arrangement was discovered between 1434:

has pointed out that the capture could have occurred if the original body was a

1077: 834:

Cumulative discoveries of just the near-Earth asteroids known by size, 1980–2024

258:, collecting a sample in 2020 which was delivered back to Earth in 2023. NASA's 17335: 17289: 16992: 16706: 16639: 16593: 16251: 16219: 16184: 15806: 15586: 15576: 15377: 15304: 15265: 15186: 15159: 15013: 14883: 14854: 14832: 14822: 14812: 14765: 14138: 14064: 14054: 13941: 13609: 13594: 13463: 13157: 13000: 12885: 12865: 12843: 12785: 12750: 12705: 12412: 12277: 12187: 12107: 11499: 11473: 11212: 11052: 11047: 10969: 10415: 10368: 10358: 10256: 10185: 10106: 9506: 9030: 8644: 8552: 8469: 8431: 8358: 7733:

Proceedings of the National Academy of Sciences of the United States of America

7408: 5533: 5532:

Lance Benner; Shantanu Naidu; Marina Brozovic; Paul Chodas (1 September 2017).

5402: 4534: 3326: 3271: 3157: 3123: 3119: 3019: 2980: 2930: 2831: 2739: 2504: 2454: 2325:, the largest object in the asteroid belt. The detection was made by using the 1839: 1789: 1759: 1538: 1481: 1298:, which implies that the asteroid's semi-major axis is also less than 0.983 AU. 1286: 1242: 1205: 1181: 693: 487: 269: 208: 10190: 9939: 9440: 8165: 7586:"Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases" 6646:"It's an asteroid! No, it's the new smallest dwarf planet in our solar system" 6597: 6390: 6365: 6101: 5705:

One idea is that Phobos and Deimos, Mars's other moon, are captured asteroids.

5263: 3658:(John Craig, 1869) lists the asteroids (and gives their pronunciations) up to 3118:, launched in 2021, is a multiple-asteroid flyby probe focused on flying by 7 2990: 2081:

formed through the accumulation of debris after collisions between asteroids.

935:) consisting of the year of discovery and an alphanumeric code indicating the 349: 17665: 17560: 17308: 17176: 17013: 16922: 16546: 16275: 16174: 16169: 15905: 15885: 15465: 15198: 15181: 15002: 14925: 14888: 14859: 14849: 14817: 14795: 14775: 14738: 14711: 14706: 14701: 14160: 14103: 14022: 13884: 13817: 13453: 13426: 13411: 13249: 13020: 12980: 12935: 12870: 12849: 12745: 12650: 12292: 11995: 11840: 11728: 11703: 11616: 11611: 11556: 11282: 11092: 10437: 10405: 10400: 10363: 10310: 9687: 9221:

Brian O'Leary; Michael J. Gaffey; David J. Ross & Robert Salkeld (1979).

8936: 8903: 8366: 8310: 7416: 6748: 6109: 5736: 4617: 3824: 3792: 3707: 3387: 3383: 3303: 3243: 3218:, launched in October 2023, is intended to study the large metallic asteroid 3105: 3038: 3005: 2724: 2610: 2580: 2538: 2203: 1767: 1596: 1589: 1367: 1363: 1359: 1337: 1303: 1262: 1209: 1098: 913:

gave it a name and a number designating its rank among asteroid discoveries,

910: 746: 550: 483: 353: 265: 243: 184: 91: 17327: 16684: 16075: 8026: 7754: 7612: 6723:. Institute for Astronomy (Press release). University of Hawaii. 19 May 2005 5627: 5586: 5563: 5454: 5354: 2583:. However, such objects could be associated with the outer planets as well. 131:. They are rocky, metallic, or icy bodies with no atmosphere, classified as 17547: 17430: 17347: 17252: 17161: 16972: 16952: 16947: 16808: 16536: 16509: 16424: 16387: 16341: 16114: 15983: 15969: 15760: 15715: 15372: 15255: 15149: 15089: 15072: 14898: 14876: 14827: 14785: 14770: 14755: 14621: 14580: 14545: 14365: 14010: 13569: 13299: 13163: 13139: 13087: 13072: 12995: 12990: 12985: 12930: 12860: 12695: 12655: 12640: 12620: 12610: 12542: 12532: 12387: 12377: 12307: 12257: 12252: 12242: 11561: 11252: 11186: 11082: 10925: 10890: 10442: 10348: 9707:, "Dynamics and Control Problems in the Deflection of Near-Earth Objects", 9038: 8570: 8439: 8384: 8022: 7970: 7834: 7773: 7677: 7631: 7522: 7504: 7334: 7265: 7150: 7116: 6870: 6540: 5822: 5803: 5362: 4307: 4193: 3619: 3433: 3414: 3337: 3087: 3076: 3024: 3010: 2975: 2970: 2716: 2685: 2561: 2520: 2317:(ESA) scientists reported the detection, for the first definitive time, of 2258: 2114: 1739: 1574: 1567: 1449: 1213: 1124: 1012: 1008: 819: 815: 563: 514: 405: 397: 329: 255: 247: 164: 116: 99: 14118: 13734: 9604:"Asteroids and adversaries: Challenging what NASA knows about space rocks" 8775:"Hubble Images of Asteroids Help Astronomers Prepare for Spacecraft Visit" 7300: 5658:, H. H. Kieffer et al., eds., Tucson: University of Arizona Press, Tucson 3890: 2146:, is 284 km (176 mi) across. The most likely reason for this is 1422:. Both moons have very circular orbits which lie almost exactly in Mars's 872:). The last step is sending the locations and time of observations to the 297:

spacecraft successfully altered the orbit of the non-threatening asteroid

40: 16331: 16280: 16241: 16024: 16018: 15801: 15789: 15784: 15735: 15710: 15680: 15675: 15623: 15618: 15443: 15357: 15316: 15277: 15154: 14985: 14908: 14871: 14760: 14170: 14049: 13894: 13857: 13624: 13097: 13092: 13077: 12880: 12838: 12828: 12810: 12805: 12775: 12770: 12730: 12725: 12710: 12605: 12582: 12572: 12567: 12547: 12497: 12487: 12397: 12367: 12337: 12297: 12282: 12167: 11825: 11408: 10487: 10353: 10174: 9980: 9774:, Geherels, T., ed. (University of Arizona Press, Tucson), pp. 1013–1034. 9509:. Jet Propulsion Laboratory. Discovery Statistics. NASA. 20 December 2018 7700:

Steigerwald, Bill; Jones, Nancy; Furukawa, Yoshihiro (18 November 2019).

6990: 6201: 6162:"The final IAU resolution on the definition of "planet" ready for voting" 5903: 5876: 5774: 5140: 3711: 3667: 3659: 3575: 3530: 3425:

in 1937. Astronomers began to realize the possibilities of Earth impact.

3410: 3406: 3370:

There is increasing interest in identifying asteroids whose orbits cross

2788: 2747: 2426: 2399: 2318: 2307: 2187: 2078: 1848: 1813: 1724: 1631:, about 40% of the total. Adding in the next three most massive objects, 1563: 1427: 1201: 1193: 1040: 986: 914: 855: 709:

difficult to predict its exact position. To recover Ceres, mathematician

545: 526: 517:

was discovered, the first object beyond the orbit of Neptune (other than

506: 502: 11154: 9561:"An empirical examination of WISE/NEOWISE asteroid analysis and results" 8408:"Asteroid lost 1 million kilograms after collision with DART spacecraft" 7560:"Harvard study suggests asteroids might play key role in spreading life" 7326: 7257: 7142: 6852: 6606: 5585:

de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (1 August 2019).

3185: 2804: 894: 683:, but similar to many others which generally are reckoned of the eighth 442:'star, planet'. In the early second half of the 19th century, the terms 198:. Several dedicated missions to asteroids were subsequently launched by 17511: 17470: 17450: 17445: 17353: 16763: 16431: 16300: 16246: 16043: 15990: 15730: 15309: 14893: 14261: 14123: 13921: 13827: 13744: 13679: 13468: 13062: 12955: 12925: 12905: 12875: 12600: 12577: 12507: 12502: 12352: 12342: 12322: 12237: 12232: 12222: 12207: 12182: 12015: 11898: 11771: 11723: 11713: 11442: 11118: 9853: 9786:"Deflection and disruption of asteroids on collision course with Earth" 9318:

John Brophy; Fred Culick; Louis Friedman; et al. (12 April 2012).

8289:"NASA's DART Data Validates Kinetic Impact as Planetary Defense Method" 7702:"First detection of sugars in meteorites gives clues to origin of life" 6433: 5482: 4086:

Weissman, Paul R.; Bottke, William F. Jr.; Levinson, Harold F. (2002).

3260: 3083: 2994: 2947: 2771: 2704: 2689: 2575:

Such objects, if associated with Earth or Venus or even hypothetically

2430: 2359: 2354: 2337: 2118: 1798: 1758:, Vesta also has an ellipsoidal shape. Vesta is the parent body of the 1755: 1542: 1185: 1036: 964: 936: 847: 811: 534: 467: 431:, meaning 'star-like, star-shaped', and derived from the Ancient Greek 345: 325: 251: 9254:"A Space Roadmap: Mine the Sky, Defend the Earth, Settle the Universe" 8874:"NASA Confirms DART Mission Impact Changed Asteroid's Motion in Space" 8674:"Suspected Asteroid Collision Leaves Odd X-Pattern of Trailing Debris" 7855:. In Bagenal, Fran; Dowling, Timothy E.; McKinnon, William B. (eds.). 7537:"Life is sweet: Sugar-packing asteroids may have seeded life on Earth" 7424: 5584: 4431:. In W. F. Bottke Jr.; A. Cellino; P. Paolicchi; R. P. Binzel (eds.). 4127: 3893:. Questions and Answers on Planets. International Astrophysical Union. 1505:

Graphs are unavailable due to technical issues. There is more info on

17552: 17321: 17186: 17181: 16802: 16796: 16753: 16679: 16583: 16336: 16226: 16004: 15997: 15426: 15392: 15223: 15144: 15067: 15062: 15033: 14780: 14733: 14602: 14585: 14153: 14133: 14128: 14037: 14015: 13998: 13869: 13842: 13812: 13689: 13674: 13654: 13619: 13579: 13384: 13359: 13354: 13329: 13324: 13319: 13314: 13309: 13294: 13269: 13264: 13259: 13244: 13233: 13208: 12855: 12833: 12760: 12755: 12735: 12720: 12715: 12690: 12645: 12512: 12407: 12267: 12197: 12035: 10378: 10343: 9723:"Interception of comets and asteroids on collision course with Earth" 9104:

Anderson, Scot W; Christensen, Korey; LaManna, Julia (3 April 2019).

8848:"NASA, SpaceX Launch DART: First Test Mission to Defend Planet Earth" 7481:"Discovery of fossil asteroidal ice in primitive meteorite Acfer 094" 5960: 5591:, a major step towards the future discovery of the Vatira population" 3663: 3649: 3626:

along with comets, centaurs, and the smaller trans-Neptunian objects.

3402: 3251: 3235: 3219: 3101: 3067: 2812: 2762: 2711:'s orbit (like an asteroid). These bodies were originally designated 2695:

Active asteroids are objects that have asteroid-like orbits but show

2543: 2422: 2414: 2405:

In November 2019, scientists reported detecting, for the first time,

2367: 2292: 2262: 2195: 2021: 1728: 1647: 1640: 1559: 1534: 1461: 1377: 1217: 982: 843: 771: 458: 298: 279: 238: 156: 17101: 15028: 9746: 9317: 8700:"Discoveries | Highlights – Tracking Evolution in the Asteroid Belt" 3122:

of varying types. While not yet set to reach its first main target,

17314: 16748: 16667: 16556: 16382: 16057: 15895: 15362: 15218: 14944: 14651: 14499: 13151: 13145: 13082: 12562: 12482: 12472: 12327: 12227: 12202: 11845: 11718: 10073: 9845: 8535: 8341: 8073: 7114: 7007: 6944:"Asteroid or mini-planet? Hubble maps the ancient surface of Vesta" 6341:(Press release). Space Telescope Science Institute. 19 April 1995. 6316:"Asteroid or mini-planet? Hubble maps the ancient surface of Vesta" 6221: 6184: 5609: 5311: 5286: 5246: 5188: 5163: 4985: 4933: 4906: 4757: 4730: 3710:

and, in the astrological community, for a few outer bodies such as

3534: 3504:

in 2022 demonstrated that spacecraft impact is a viable option for

3398: 3239: 3028: 2130: 2126: 1982: 1720: 1636: 1585: 1530: 990: 941: 926: 755: 701:. The information was published in the September 1801 issue of the 648: 521:); soon large numbers of similar objects were observed, now called 450:(not always qualified as "minor") were still used interchangeably. 341: 232: 213: 83: 9423: 8248: 7728:"Extraterrestrial ribose and other sugars in primitive meteorites" 7673:"DNA building blocks can be made in space, NASA evidence suggests" 7071: 5721:

American Association for the Advancement of Science Annual Meeting

5114:"New study reveals twice as many asteroids as previously believed" 4571:

The Titius-Bode Law of Planetary Distances: Its History and Theory

3255:

is planned to launch in 2025. If all goes as planned, it will use

3246:, as well as various minor bodies. Its launch is planned for 2024. 505:, ventured farther for part of their orbit. Starting in 1977 with 187:. The total mass of all the asteroids combined is only 3% that of 17358: 17079: 16889: 16603: 16519: 15299: 15287: 15213: 14612: 14590: 14465: 14450: 12177: 11397: 9534: 9407: 9282: 8935: