Mars - Knowledge

2193: 1566: 3360: 2895: 23729: 1986: 53: 2709:, based on spectrometer readings of the darkened areas of slopes. These streaks flow downhill in Martian summer, when the temperature is above −23 °C, and freeze at lower temperatures. These observations supported earlier hypotheses, based on timing of formation and their rate of growth, that these dark streaks resulted from water flowing just below the surface. However, later work suggested that the lineae may be dry, granular flows instead, with at most a limited role for water in initiating the process. A definitive conclusion about the presence, extent, and role of liquid water on the Martian surface remains elusive. 2324: 2443: 2779: 2174:. The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters". Cave entrances measure from 100 to 252 metres (328 to 827 ft) wide and they are estimated to be at least 73 to 96 metres (240 to 315 ft) deep. Because light does not reach the floor of most of the caves, they may extend much deeper than these lower estimates and widen below the surface. "Dena" is the only exception; its floor is visible and was measured to be 130 metres (430 ft) deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, 4036: 2427: 3275: 20750: 20742: 2571:. The gullies tend to be in the highlands of the Southern Hemisphere and face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process involves liquid water, probably from melting ice, although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust. No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly still active. Other geological features, such as 1872: 1341: 2481: 1417: 2864: 2489: 4193: 2891:) is second only to Venus in apparent brightness. Mars usually appears distinctly yellow, orange, or red. When farthest away from Earth, it is more than seven times farther away than when it is closest. Mars is usually close enough for particularly good viewing once or twice at 15-year or 17-year intervals. Optical ground-based telescopes are typically limited to resolving features about 300 kilometres (190 mi) across when Earth and Mars are closest because of Earth's atmosphere. 4077:, which for the Sun is estimated to extend from within the orbit of Earth to about that of Mars. During perihelion, Mars dips inside this region, but Mars's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life. 103: 24011: 20734: 2108: 16949: 1215:. About 60% of the surface of Mars shows a record of impacts from that era, whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. However, more recent modeling has disputed the existence of the Late Heavy Bombardment. There is evidence of an enormous impact basin in the Northern Hemisphere of Mars, spanning 10,600 by 8,500 kilometres (6,600 by 5,300 mi), or roughly four times the size of the Moon's 4347:'s books on the subject put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works. Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever". High-resolution mapping of the surface of Mars revealed no artifacts of habitation, but pseudoscientific speculation about intelligent life on Mars still continues. Reminiscent of the 2943: 3115: 23909: 23977: 2899: 4279: 2898: 2902: 2901: 2896: 3611: 23994: 23960: 2903: 23943: 23869: 23705: 16961: 21833: 23926: 3645: 2900: 23717: 2967: 23881: 15060: 14119: 14084: 12318: 12281: 11729: 11662: 11513: 11380: 11344: 11208: 11146: 10960: 10739: 10703: 10442: 10327: 10257: 10091: 10054: 9847: 9188: 7934: 7394: 7357: 6257: 5247: 4643: 23857: 2737:, though not significantly high enough to suggest the former presence of an ocean. Other scientists caution that these results have not been confirmed, and point out that Martian climate models have not yet shown that the planet was warm enough in the past to support bodies of liquid water. Near the northern polar cap is the 81.4 kilometres (50.6 mi) wide 1425: 2549:, is 700 kilometres (430 mi) long, much greater than the Grand Canyon, with a width of 20 kilometres (12 mi) and a depth of 2 kilometres (1.2 mi) in places. It is thought to have been carved by flowing water early in Mars's history. The youngest of these channels is thought to have formed only a few million years ago. 2008:. The edifice is over 600 km (370 mi) wide. Because the mountain is so large, with complex structure at its edges, giving a definite height to it is difficult. Its local relief, from the foot of the cliffs which form its northwest margin to its peak, is over 21 km (13 mi), a little over twice the height of 22146: 1714:

are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other

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have been proposed throughout the 20th and 21st centuries, but none have come to fruition. The NASA Authorization Act of 2017 directed NASA to study the feasibility of a crewed Mars mission in the early 2030s; the resulting report eventually concluded that this would be unfeasible. In addition, in

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Valleys", also known as Agathodaemon in the old canal maps), has a length of 4,000 kilometres (2,500 mi) and a depth of up to 7 kilometres (4.3 mi). The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison,

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are named for classical mythology. Craters larger than roughly 50 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Smaller craters are named for towns and villages of the world with populations of less than 100,000. Large valleys are named

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The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summers) in combination with the canals led to speculation about life on Mars, and it was a long-held belief that Mars contained vast seas and vegetation. As bigger telescopes were used,

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have been detected on Mars. Because Mars lacks a global magnetic field, the types and distribution of auroras there differ from those on Earth; rather than being mostly restricted to polar regions as is the case on Earth, a Martian aurora can encompass the planet. In September 2017, NASA reported

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of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. It is possible that, four billion years ago, the Northern Hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's

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when it is winter in its southern hemisphere and summer in its northern. As a result, the seasons in its southern hemisphere are more extreme and the seasons in its northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer

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near the equator, which is unusual for captured objects, and the required capture dynamics are complex. Accretion early in the history of Mars is plausible, but would not account for a composition resembling asteroids rather than Mars itself, if that is confirmed. Mars may have yet-undiscovered

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which had 30- and 45-centimetre (12- and 18-in) telescopes. The observatory was used for the exploration of Mars during the last good opportunity in 1894, and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the

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Martian surface temperatures vary from lows of about −110 °C (−166 °F) to highs of up to 35 °C (95 °F) in equatorial summer. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure (about 1% that of the

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on Earth is only 446 kilometres (277 mi) long and nearly 2 kilometres (1.2 mi) deep. Valles Marineris was formed due to the swelling of the Tharsis area, which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a

2545:, cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava. One of the larger examples, 2260:, with a mean pressure at the surface level of 600 Pa (0.087 psi). The highest atmospheric density on Mars is equal to that found 35 kilometres (22 mi) above Earth's surface. The resulting mean surface pressure is only 0.6% of Earth's 101.3 kPa (14.69 psi). The 4056:

observed the planet and found that "if water vapor or oxygen occur in the atmosphere of Mars it is in quantities too small to be detected by spectroscopes then available". That observation contradicted many of the measurements of the time and was not widely accepted. Campbell and

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in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase global temperature.

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Water in its liquid form cannot prevail on the surface of Mars due to the low atmospheric pressure on Mars, which is less than 1% that of Earth, only at the lowest of elevations pressure and temperature is high enough for water being able to be liquid for short periods.

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in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium (D/H = 9.3 ± 1.7 10) is five to seven times the amount on Earth (D/H = 1.56 10), suggesting that ancient Mars had significantly higher levels of water. Results from the

1879:-based topographic map showing highlands (light colors) dominating the Southern Hemisphere of Mars, lowlands (dark colors) the northern. Volcanic plateaus delimit regions of the northern plains, whereas the highlands are punctuated by several large impact basins. 2897: 1428: 2583:

across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence. Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as

1431: 1430: 1426: 10832:'conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water'... 'Liquid water is typically stable at the lowest elevations and at low latitudes on the planet because the atmospheric pressure is greater than the 4168:, formed by the impact of meteors, which on Earth can preserve signs of life, has also been found on the surface of the impact craters on Mars. Likewise, the glass in impact craters on Mars could have preserved signs of life, if life existed at the site. 1806:

were the first areographers. They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars.

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during the northern winter to about 0.65 ppb during the summer. Estimates of its lifetime range from 0.6 to 4 years, so its presence indicates that an active source of the gas must be present. Methane could be produced by non-biological process such as

1832:(Mount Olympus). The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian "continents" and given names like 4073: – the ability of a world to develop environmental conditions favorable to the emergence of life – favors planets that have liquid water on their surface. Most often this requires the orbit of a planet to lie within the 4988: 3063:

A third possibility for their origin as satellites of Mars is the involvement of a third body or a type of impact disruption. More-recent lines of evidence for Phobos having a highly porous interior, and suggesting a composition containing mainly

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has a larger orbital eccentricity. It is known that in the past, Mars has had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today. Mars's

1785: 2848:, is 780 days; but the number of days between successive oppositions can range from 764 to 812. The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' 1784: 3575:

mission, designed to search for evidence of past life, which was intended to be launched in 2018 but has been repeatedly delayed, with a launch date pushed to 2028 at the earliest. The project was restarted in 2024 with additional

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in 1925 that the myth of the Earth-like habitability of Mars was finally broken. However, even in the 1960s, articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars.

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The depiction of Mars in fiction has been stimulated by its dramatic red color and by nineteenth-century scientific speculations that its surface conditions might support not just life but intelligent life. This gave way to many

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In April 2024, NASA selected several companies to begin studies on providing commercial services to further enable robotic science on Mars. Key areas include establishing telecommunications, payload delivery and surface imaging.

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The Mariner 4 mission, the second of two Mars flyby attempts launched in 1964 by NASA, was one of the great early successes of the agency, and indeed the Space Age, returning the very first photos of another planet from deep

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spacecraft had returned pictures of Mars as a lifeless and canal-less world, these ideas about Mars were abandoned; for many science-fiction authors, the new discoveries initially seemed like a constraint, but eventually the

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mission, which launched in 1996 and operated until late 2006, produced complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals. These maps are available online at websites including

2080:, which is around 1,500 kilometres (930 mi) in diameter. Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the 1519:

compared to Earth. Below this the mantle gradually becomes more ductile, and the seismic wave velocity starts to grow again. The Martian mantle does not appear to have a thermally insulating layer analogous to Earth's

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rover for possible return to Earth and further examination. Although highly intriguing, no definitive final determination on a biological or abiotic origin of this rock can be made with the data currently available.

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to a gaseous state). Mars is nearly, or perhaps totally, geologically dead; the end of volcanic activity has apparently stopped the recycling of chemicals and minerals between the surface and interior of the planet.

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Mars is approximately half the diameter of Earth, with a surface area only slightly less than the total area of Earth's dry land. Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's

3169:. Commonly, the Greek name for the planet now referred to as Mars, was Ares. It was the Romans who named the planet Mars, for their god of war, often represented by the sword and shield of the planet's namesake. 2856:. At their furthest Mars and Earth can be as far as 401 million km (249 million mi) apart. Mars comes into opposition from Earth every 2.1 years. The planets come into opposition near Mars's 4328:, a circle with a spear pointing out to the upper right, is also used as a symbol for the male gender. The symbol dates from at least the 11th century, though a possible predecessor has been found in the Greek 3310:

were supposedly long, straight lines on the surface of Mars, to which he gave names of famous rivers on Earth. His term, which means "channels" or "grooves", was popularly mistranslated in English as "canals".

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contained within Martian minerals, is equal to or greater than that of Earth at 50–300 parts per million of water, which is enough to cover the entire planet to a depth of 200–1,000 metres (660–3,280 ft).

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launch vehicle with the goal of Mars colonization. In plans shared with the company in April 2024, Elon Musk envisions the beginning of a Mars colony within the next twenty years. This enabled by the planned

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Mariner 4...represented the first successful flyby of the planet Mars, returning the first pictures of the martian surface. These represented the first images of another planet ever returned from deep space.

2994:(about 12 kilometres (7.5 mi) in diameter), which orbit close to the planet. The origin of both moons is unclear, although a popular theory states that they were asteroids captured into Martian orbit. 7569: 3480:

continued exploring with new instruments and supporting lander missions. NASA provides two online tools: Mars Trek, which provides visualizations of the planet using data from 50 years of exploration, and

2756:(which is 12,100 cubic kilometers). During observations from 2018 through 2021, the ExoMars Trace Gas Orbiter spotted indications of water, probably subsurface ice, in the Valles Marineris canyon system. 10238: 1787: 3290:

By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. On 5 September 1877, a perihelic opposition to Mars occurred. The Italian astronomer

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The history of observations of Mars is marked by oppositions of Mars when the planet is closest to Earth and hence is most easily visible, which occur every couple of years. Even more notable are the

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of any class. It is also possible that Phobos and Deimos were fragments of an older moon, formed by debris from a large impact on Mars, and then destroyed by a more recent impact upon the satellite.

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overlaid by less dense rocky layers. The outermost layer is the crust, which is on average about 42–56 kilometres (26–35 mi) thick, with a minimum thickness of 6 kilometres (3.7 mi) in

9377: 3854: 14287: 3910: 3734: 3931: 3137:. In Mesopotamian texts, Mars is referred to as the "star of judgement of the fate of the dead". The existence of Mars as a wandering object in the night sky was also recorded by the ancient 3802: 3786: 3770: 15391: 14186: 3969: 3836: 2626:, which also forms in the presence of water, was found on the surface by NASA's Mars rover Opportunity. It is estimated that the amount of water in the upper mantle of Mars, represented by 2579:

preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history. Such conditions necessarily require the widespread presence of

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used to make a preliminary calculation of the relative distance to the planet. From Brahe's observations of Mars, Kepler deduced that the planet orbited the Sun not in a circle, but in an

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Mars is scarred by a number of impact craters: a total of 43,000 observed craters with a diameter of 5 kilometres (3.1 mi) or greater have been found. The largest exposed crater is

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During the late 19th century, it was widely accepted in the astronomical community that Mars had life-supporting qualities, including the presence of oxygen and water. However, in 1894

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composition have been regarded as similar to asteroids, supporting a capture theory. The unstable orbit of Phobos would seem to point toward a relatively recent capture. But both have

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of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase in

3188:, attempted to address the problem of the orbital motion of Mars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection later called the 15355: 14372: 12599: 12183: 3602:

As of February 2024, debris from these types of missions has reached over seven tons. Most of it consists of crashed and inactive spacecraft as well as discarded components.

1427: 3282:, showing canals snaking through the Martian landscape. At the time, the existence of canals was still highly controversial as no close-up pictures of Mars had been taken (until 2844:, where the Earth and Mars are at opposite sides of the Solar System and form a straight line crossing the Sun. The average time between the successive oppositions of Mars, its 7018: 14562: 11714: 10009: 1646:, observations show that parts of the planet's crust have been magnetized, suggesting that alternating polarity reversals of its dipole field have occurred in the past. This 23632: 23206: 15647: 15174: 1515:, where the velocity of seismic waves is lower than surrounding depth intervals. The mantle appears to be rigid down to the depth of about 250 km, giving Mars a very thick 10757: 6332: 3048:

from Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet.

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ions in sufficiently high concentrations to suggest that they are widespread on Mars. UV and X-ray radiation would turn chlorate and perchlorate ions into other, highly

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and lower surface pressure may be why sound is attenuated more on Mars, where natural sources are rare apart from the wind. Using acoustic recordings collected by the

11643: 8320:"New Mars Map Lets You 'See the Whole Planet at Once' - Scientists assembled 3,000 images from an Emirati orbiter to create the prettiest atlas yet of the red planet" 4903:

Konopliv AS, Asmar SW, Folkner WM, et al. (January 2011). "Mars high resolution gravity fields from MRO, Mars seasonal gravity, and other dynamical parameters".

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provided evidence of subsurface water, amounting to as much as 4% water content, down to a depth of 60 centimetres (24 in), during the rover's traverse from the

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Mars without (on left) and with a global dust storm in July 2001 (on right), including different visible water ice cloud covers, as seen by the Hubble Space Telescope

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that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as

23403: 14633: 13470: 4682: 3236:. When the telescope became available, the diurnal parallax of Mars was again measured in an effort to determine the Sun-Earth distance. This was first performed by 2508:. The volume of water ice in the south polar ice cap, if melted, would be enough to cover most of the surface of the planet with a depth of 11 metres (36 ft). 3133:, the god of war and plague. During Sumerian times, Nergal was a minor deity of little significance, but, during later times, his main cult center was the city of 2786:

Mars's average distance from the Sun is roughly 230 million km (143 million mi), and its orbital period is 687 (Earth) days. The solar day (or

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Mars has seasons, alternating between its northern and southern hemispheres, similar to on Earth. Additionally the orbit of Mars has, compared to Earth's, a large

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and other minerals known from Mars, point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the

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period: Formation of the oldest extant surfaces of Mars, 4.5 to 3.5 billion years ago. Noachian age surfaces are scarred by many large impact craters. The

1693:. These nutrients are found in soils on Earth. They are necessary for growth of plants. Experiments performed by the lander showed that the Martian soil has a 1539:

core is completely molten, with no solid inner core. It is around half of Mars's radius, approximately 1650–1675 km, and is enriched in light elements such as

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rover, researchers concluded that the speed of sound there is approximately 240 m/s for frequencies below 240 Hz, and 250 m/s for those above.

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would quickly break down in the Martian atmosphere. Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as

3620: 10039: 3157:, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets. In 6840: 5804: 4564:

Simon J, Bretagnon P, Chapront J, et al. (February 1994). "Numerical expressions for precession formulae and mean elements for the Moon and planets".

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hundreds of meters deep, though this theory remains controversial. In March 2015, scientists stated that such an ocean might have been the size of Earth's

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obstacles in their path. The commonly accepted hypotheses include that they are dark underlying layers of soil revealed after avalanches of bright dust or

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Bagheri A, Khan A, Efroimsky M, et al. (22 February 2021). "Dynamical evidence for Phobos and Deimos as remnants of a disrupted common progenitor".

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production on exposure to water and nutrients. This sign of life was later disputed by scientists, resulting in a continuing debate, with NASA scientist

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were making regular records of the positions of the planets and systematic observations of their behavior. For Mars, they knew that the planet made 37

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Huang Y, Chubakov V, Mantovani F, et al. (June 2013). "A reference Earth model for the heat-producing elements and associated geoneutrino flux".

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are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by

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Kounaves SP (2014). "Evidence of martian perchlorate, chlorate, and nitrate in Mars meteorite EETA79001: implications for oxidants and organics".

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detected the weak Martian radiation belt, measured at about 0.1% that of Earth, and captured the first images of another planet from deep space.

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period: 3.5 to between 3.3 and 2.9 billion years ago. The Hesperian period is marked by the formation of extensive lava plains. Named after

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Krasnopolsky, Vladimir A., Maillard, Jean-Pierre, Owen, Tobias C. (2004). "Detection of methane in the Martian atmosphere: evidence for life?".

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bulge, a volcanic upland, is thought to have formed during this period, with extensive flooding by liquid water late in the period. Named after

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probe in 1976. As of 2023, there are at least 11 active probes orbiting Mars or on the Martian surface. Mars is an attractive target for future

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stories before the mid-sixties. Since then, depictions of Martians have also extended to animation. A comic figure of an intelligent Martian,

23191: 10720: 3256:, who was first to see it via telescope. The first person to draw a map of Mars that displayed any terrain features was the Dutch astronomer 2021: 12889: 12744: 10072: 8288: 6206: 5932: 12859: 11127: 9557: 8942: 8713: 6063: 4623: 992: 12498: 11494: 11193: 9214: 23336: 21491: 16998: 15308: 15259: 14484: 13352: 12401: 10459: 10305: 7312: 2564:

may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.

2016:, over 1,000 km (620 mi) to the northwest, to the summit approaches 26 km (16 mi), roughly three times the height of 1181: 14065: 13285: 12635: 12173: 7952: 3060:

moons, smaller than 50 to 100 metres (160 to 330 ft) in diameter, and a dust ring is predicted to exist between Phobos and Deimos.

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visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as

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of the atmosphere is about 10.8 kilometres (6.7 mi), which is higher than Earth's 6 kilometres (3.7 mi), because the surface

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Fernando B, Daubar IJ, Charalambous C, et al. (October 2023). "A Tectonic Origin for the Largest Marsquake Observed by InSight".

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10,600 by 8,500 kilometres (6,600 by 5,300 mi) in size, or roughly the area of Europe, Asia, and Australia combined, surpassing

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Murray JB (17 March 2005). "Evidence from the Mars Express High Resolution Stereo Camera for a frozen sea close to Mars' equator".

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observations, these speculations are based on small scale features perceived in the spacecraft images, such as "pyramids" and the "

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have detected ionized atmospheric particles trailing off into space behind Mars, and this atmospheric loss is being studied by the

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features retain many of the older names but are often updated to reflect new knowledge of the nature of the features. For example,

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Wieczorek MA, Broquet A, McLennan SM, et al. (May 2022). "InSight Constraints on the Global Character of the Martian Crust".

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was the first spacecraft to visit Mars; launched on 28 November 1964, it made its closest approach to the planet on 15 July 1965.

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Ardalan AA, Karimi R, Grafarend EW (2009). "A New Reference Equipotential Surface, and Reference Ellipsoid for the Planet Mars".

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due to the absence of a magnetosphere and has insufficient atmospheric pressure to retain water in a liquid form (water instead

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repeated the study in 1909 using better instruments, but with the same results. It was not until the findings were confirmed by

2084:, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period 23257: 22902: 22887: 22867: 22179: 22126: 21946: 21934: 21929: 16279: 15105: 12566: 11975: 10153: 7853: 6278: 5224: 4238:

on Mars, until the Mars colony reaches full self sustainability.Any future human mission to Mars will likely take place within

1891:), by choice of an arbitrary point; Mädler and Beer selected a line for their first maps of Mars in 1830. After the spacecraft 22175: 22160: 15166: 15082: 12657: 11777:

Ojha L, Wilhelm MB, Murchie SL, et al. (2015). "Spectral evidence for hydrated salts in recurring slope lineae on Mars".

5544:

Halliday, A. N., Wänke, H., Birck, J.-L., et al. (2001). "The Accretion, Composition and Early Differentiation of Mars".

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system concept for autonomous robotic excavation and processing of Mars soil to extract water for use in exploration missions.

2192: 23201: 22934: 22897: 22892: 22169: 21321: 17755: 17490: 16418: 16403: 15924: 15903: 15867: 15840: 15815: 15784: 15751: 15622: 15443: 14808: 14394: 14170: 14145: 13839: 13806: 13630: 13591: 13557: 13503: 13437: 13410: 13385: 13239: 13206: 13124: 12805: 12423:

Petropoulos AE, Longuski JM, Bonfiglio EP (2000). "Trajectories to Jupiter via Gravity Assists from Venus, Earth, and Mars".

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Mahaffy PR (19 July 2013). "Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover".

9408: 9356: 8707: 8469: 8272: 8157: 7972: 5612: 5498: 5470: 4884: 4843: 4676: 16877: 15956: 15414: 15041: 14225: 12695: 6137: 24051: 23627: 23564: 23218: 22939: 22877: 22872: 22168: 21695: 16134: 11647: 7600: 5750: 5433: 2347: 22166: 22163: 22159: 22155: 14624: 11325: 23897: 23781: 22882: 21326: 20698: 17894: 16632: 16219: 11442: 9432: 7741: 7342: 6510:

Kim D, Duran C, Giardini D, et al. (June 2023). "Global Crustal Thickness Revealed by Surface Waves Orbiting Mars".

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of Martian soil. The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.

22173: 22165: 8993:"Structural analysis of the Valles Marineris fault zone: Possible evidence for large-scale strike-slip faulting on Mars" 1719:. Several other explanations have been put forward, including those that involve water or even the growth of organisms. 22162: 20595: 16872: 10662: 8015: 5632: 4751:(Perihelion occurs when rdot flips from negative to positive). Solar System Dynamics Group, Jet Propulsion Laboratory. 1753:

with potentially levels as low as 0.064 millisieverts per day, comparable to radiation levels during flights on Earth.

1204:, are much more common on Mars than on Earth; these elements were probably pushed outward by the young Sun's energetic 22180: 22176: 14719:

Kopparapu RK, Ramirez R, Kasting JF, et al. (2013). "Habitable Zones Around Main-Sequence Stars: New Estimates".

13856: 11821: 2682: 23030: 23003: 22171: 21898: 21726: 21608: 21452: 17600: 16501: 15718: 12236: 11854: 11464: 9905: 1811: 1776: 1565: 1250:

3.5 billion years to 4 billion years ago. This ring system may have been formed from a moon, 20 times more

914: 14985:

Schultz PH, Harris RS, Clemett SJ, et al. (June 2014). "Preserved flora and organics in impact melt breccias".

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From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Earth's satellite, the

23418: 22181: 20455: 19305: 15670: 14248: 10758:"Formation of Martian gullies by the action of liquid water flowing under current Martian environmental conditions" 9591: 8659: 4831: 4218: 3419: 3233: 14455: 10388: 10031: 9667:(6 August 2009). "Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics". 8969: 6244: 2879:

from the Sun can range from about −3.0 to −1.4. The minimum brightness is magnitude +1.86 when the planet is near

2454:(not water ice) coverage on the north (left) and south (right) poles of Mars between northern and southern summer. 21688: 21467: 21296: 19310: 17332: 16991: 16154: 10765: 9296:

Lundin, R (2004). "Solar Wind-Induced Atmospheric Erosion at Mars: First Results from ASPERA-3 on Mars Express".

9139: 5960: 2373: 2159: 2020:, which in comparison stands at just over 8.8 kilometres (5.5 mi). Consequently, Olympus Mons is either the 1950: 342: 24017: 22946: 21803: 6793: 3040:. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside 1261:

The geological history of Mars can be split into many periods, but the following are the three primary periods:

23597: 23013: 22847: 21772: 21673:

Missions are ordered by launch date. Sign indicates failure en route or before intended mission data returned.

18759: 18746: 17007: 16194: 16031: 15988: 8735: 8597: 6159: 5985: 4093: 862: 177: 19913: 15282: 14035: 5197: 1011:'s planets with a diameter of 6,779 km (4,212 mi). In terms of orbital motion, a Martian solar day ( 23122: 23018: 21893: 21422: 20554: 20218: 17252: 14825: 12919: 8628: 8088:

Archinal, B. A., Caplinger, M. (Fall 2002). "Mars, the Meridian, and Mert: The Quest for Martian Longitude".

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Mallama A, Hilton JL (October 2018). "Computing apparent planetary magnitudes for The Astronomical Almanac".

4100:

Evidence suggests that the planet was once significantly more habitable than it is today, but whether living

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of Mars is +0.71 with a standard deviation of 1.05. Because the orbit of Mars is eccentric, the magnitude at

1456:

For comparison, Earth's crust averages 27.3 ± 4.8 km in thickness. The most abundant elements in the Martian

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Wetherill GW (1999). "Problems Associated with Estimating the Relative Impact Rates on Mars and the Moon".

4640:; Mean Anomaly (deg) 19.412 = (Mean Longitude (deg) 355.45332) – (Longitude of perihelion (deg) 336.04084) 4514:

The light filters are 635 nm, 546 nm, and 437 nm, roughly corresponding to red, green and blue respectively

4235: 4074: 1876: 23540: 22178: 22066: 17843: 17804: 15803:

The science fiction and fantasy readers' advisory: the librarian's guide to cyborgs, aliens, and sorcerers

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Malin MC, Edgett KS (30 June 2000). "Evidence for Recent Groundwater Seepage and Surface Runoff on Mars".

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wrote: "Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears."

2515:

Water in the atmosphere is small, but enough to produce larger clouds of water ice and different cases of

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Paris A, Davies E, Tognetti L, et al. (27 April 2020). "Prospective Lava Tubes at Hellas Planitia".

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orbiter found to be filled with approximately 2,200 cubic kilometres (530 cu mi) of water ice.

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of radiation per day, and significantly less than the radiation of 1.84 millisieverts per day or 22

1722: 1322: 1216: 17: 23137: 14514: 14343: 12055: 8686: 6230: 4239: 2068:, which is 2,300 kilometres (1,400 mi) wide and 7,000 metres (23,000 ft) deep, and is a light 23847: 23612: 23413: 23296: 23279: 23245: 22177: 22119: 21562: 20368: 20088: 20058: 19983: 19808: 19573: 19558: 19357: 19325: 19230: 19100: 19080: 19030: 19010: 18827: 18265: 18088: 17848: 17557: 17277: 16984: 16769: 16602: 16473: 16359: 16246: 15485: 12121:

Head, J.W. (1999). "Possible Ancient Oceans on Mars: Evidence from Mars Orbiter Laser Altimeter Data".

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Byrne, Shane, Ingersoll, Andrew P. (2003). "A Sublimation Model for Martian South Polar Ice Features".

8319: 5773: 4080:

The environmental conditions on Mars are a challenge to sustaining organic life: the planet has little

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in the 1960s and 1970s, many previous concepts of Mars were radically broken. After the results of the

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in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition.

2678: 2674: 2662: 1175: 19958: 19833: 17740: 7764: 7623: 5591:. Washington DC American Geophysical Union Geophysical Monograph Series. Vol. 74. pp. 7–17. 3106:

of Mars, which are distinguished because Mars is close to perihelion, making it even closer to Earth.

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A City on Mars: Can we settle space, should we settle space, and have we really thought this through?

15460: 12337:"The evidence for unusually high hydrogen abundances in the central part of Valles Marineris on Mars" 10283: 8226:

Zeitler, W., Ohlhof, T., Ebner, H. (2000). "Recomputation of the global Mars control-point network".

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Temperatures taken are the average mean daily minimum and maximum on per year basis, data taken from

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An animation to explain the (apparent) retrograde motion of Mars, using actual 2020 planet positions

1211:

After the formation of the planets, the inner Solar System may have been subjected to the so-called

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Planetary Astronomy from the Renaissance to the Rise of Astrophysics, Part A, Tycho Brahe to Newton

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in 1672. The early parallax measurements were hampered by the quality of the instruments. The only

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region. The volume of water detected has been estimated to be equivalent to the volume of water in

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Along craters and canyon walls, there are thousands of features that appear similar to terrestrial

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Martian craters can have a morphology that suggests the ground became wet after the meteor impact.

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life-detection experiments, the hypothesis of a dead planet was generally accepted. The data from

1914: 1677:

lander returned data showing Martian soil to be slightly alkaline and containing elements such as

23435: 23262: 22909: 22813: 22726: 22426: 22276: 22167: 22158: 21856: 21088: 20693: 20505: 20408: 20348: 20298: 20293: 20228: 20078: 20048: 19973: 19963: 19903: 19818: 19743: 19728: 19693: 19688: 19683: 19653: 19623: 19618: 19593: 19543: 19270: 19255: 19050: 18962: 17287: 16189: 16046: 13581: 12946: 8353:"Welcome to Mars! Caltech's Jaw-Dropping, 5.7 Terapixel Virtual Expedition Across the Red Planet" 5924: 5300:"Mars' Surface Radiation Environment Measured with the Mars Science Laboratory's Curiosity Rover" 3540: 3069: 2884: 2841: 2791: 2484:

Mars contains water, though mostly as dust covered polar layers of ice, as mapped in this image.

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occurred less than 20 million years ago, indicating equally recent volcanic intrusions. The

638: 412: 286: 155: 127: 52: 12881: 12851: 12736: 11189: 11131: 8914: 8264: 6190: 6055: 6007:

Hartmann, William K., Neukum, Gerhard (2001). "Cratering Chronology and the Evolution of Mars".

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to help produce the first detailed map of Mars. These maps notably contained features he called

2614:. This forms only in the presence of acidic water, showing that water once existed on Mars. The 23440: 23378: 23326: 23316: 23301: 23252: 23112: 23042: 22464: 22152: 22088: 21547: 21503: 21239: 21117: 21062: 20450: 20303: 20288: 20273: 20268: 19868: 19823: 19803: 19678: 19658: 19603: 19578: 19477: 19467: 19462: 19427: 19392: 19265: 19240: 19195: 19155: 18985: 18395: 18190: 18115: 17784: 17594: 17470: 17392: 17367: 17272: 17242: 17227: 16579: 16554: 16391: 16294: 16236: 16168: 16056: 15807: 15801: 14620: 13831: 13823: 13526: 13430:

The Shorter Science and Civilisation in China: An Abridgement of Joseph Needham's Original Text

13194: 12506: 11045: 10782: 8235: 7236: 7175: 4783:"Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006" 4488: 4389: 4070: 3374: 3198:

for the next fourteen centuries. Literature from ancient China confirms that Mars was known by

3052: 2833: 2706: 2553: 2505: 2463: 1654:. One hypothesis, published in 1999 and re-examined in October 2005 (with the help of the 1643: 1212: 23361: 22172: 22164: 22161: 15776: 15223: 14476: 13461:. American Lectures on the History of Religions, volume 10. G. P. Putnam's Sons. p. 300. 13454: 13231: 13141: 12385: 11498: 10836:

of water and surface temperatures in equatorial regions can reach 273 K for parts of the day '

10724: 10463: 10312: 8459: 8289:"ESA Science & Technology - Using iMars: Viewing Mars Express data of the MC11 quadrangle" 7880:

International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)

7265: 4835: 4666: 4145:, indicating that any organic molecules would have to be buried under the surface to survive. 1312:

is home to sheet-like lava flows created about 200 million years ago. Water flows in the

1292:

period: between 3.3 and 2.9 billion years ago to the present. Amazonian regions have few

24036: 23806: 23733: 23607: 23460: 23423: 23311: 23306: 22112: 22078: 22020: 21977: 21711: 21567: 21537: 20717: 20658: 20612: 20590: 20413: 20173: 20163: 20003: 19848: 19828: 19538: 19504: 19447: 19300: 19185: 19085: 19025: 18995: 18570: 17779: 17650: 17630: 17612: 17530: 17510: 17460: 17455: 17352: 17267: 16774: 16754: 16627: 16438: 16386: 16381: 16364: 16241: 16226: 15710:

Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing 'Hoax'

14889: 14319: 13493: 13308: 13277: 13114: 8115: 7624:"Slope streaks on Mars: Correlations with surface properties and the potential role of water" 4541: 4379: 4340: 4283: 4251: 4205: 4035: 3891: 3584: 3528: 3379: 3328: 3291: 3146: 2713: 2381: 2249: 2217: 1536: 1348: 1163: 774: 372: 58: 37: 23475: 15768: 15552: 15136:"S.442 - National Aeronautics and Space Administration Transition Authorization Act of 2017" 14318: 14057: 13659: 13375: 13223: 12627: 12467: 11226: 10239:"Large Solar Storm Sparks Global Aurora and Doubles Radiation Levels on the Martian Surface" 9787: 9065: 8880: 8867:

Costard FM (1989). "The spatial distribution of volatiles in the Martian hydrolithosphere".

7439:"Wet Chemistry Experiments on the 2007 Phoenix Mars Scout Lander: Data Analysis and Results" 6104: 5723: 5395: 4958: 4868: 4721: 4577: 2492:

As top surface layer water appears readily visible at some places on Mars, as in this polar

2012:

as measured from its base on the ocean floor. The total elevation change from the plains of

23368: 23321: 22978: 22436: 22401: 22396: 22290: 22241: 22214: 22170: 22149: 22083: 22046: 21915: 21613: 21582: 21577: 21253: 21009: 20946: 20934: 20928: 20914: 20806: 20705: 20435: 20343: 20208: 20168: 19521: 19387: 19110: 18942: 17485: 17439: 17297: 16789: 16784: 16571: 15548: 15323: 15235: 14996: 14901: 14864: 14738: 14669: 13940: 13733: 13725: 13682: 13655: 13320: 13176: 13079: 13000: 12955: 12432: 12348: 12130: 12067: 12010: 11933: 11922:"Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water" 11866: 11786: 11605: 11297: 11241: 11082: 11037: 10986: 10898: 10774: 10612: 10525: 10357: 10345: 10191: 10121: 9940: 9879: 9783: 9734: 9676: 9606: 9514: 9463: 9305: 9252: 9004: 8926: 8876: 8833: 8551: 8540:, Banerdt WB (2008). "The Borealis basin and the origin of the Martian crustal dichotomy". 8494: 8430: 8131: 8097: 8050: 7690: 7638: 7495: 7450: 7280: 7228: 7167: 7112: 7053: 6945: 6878: 6808: 6764: 6705: 6654: 6619: 6564: 6519: 6455: 6443: 6372: 6290: 6100: 6016: 5969: 5857: 5719: 5682: 5679:

MEVTV Workshop on Early Tectonic and Volcanic Evolution of Mars. LPI Technical Report 89-04

5644: 5592: 5553: 5391: 5311: 5163: 5120: 5109:"Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015" 5011: 4954: 4912: 4794: 4717: 4573: 4453: 4394: 4307: 4242:, which occurs every 26 months. The moon Phobos has been proposed as an anchor point for a 4222: 4180: 3878: 3860: 3637: 3550: 3482: 3459: 3403: 3368: 3150: 3103: 2876: 2817: 2701:

terrain. In September 2015, NASA announced that they had found strong evidence of hydrated

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Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic

2426: 2399: 2241: 2222: 1730: 1673: 1656: 1620: 1368: 895: 209: 24000: 22153: 22151: 11680: 11227:"Stratigraphic analysis of the distributary fan in Eberswalde crater using stereo imagery" 10945: 10427: 9723:"Have olivine, will gas: Serpentinization and the abiogenic production of methane on Mars" 8792: 7158:

McSween HY, Taylor GJ, Wyatt MB (May 2009). "Elemental Composition of the Martian Crust".

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for the word "Mars" or "star" in various languages; smaller valleys are named for rivers.

8: 23820: 23709: 23547: 23520: 23470: 23274: 22738: 22431: 22283: 22051: 21910: 21756: 21517: 21341: 21267: 21081: 20921: 20824: 20500: 20430: 19948: 19943: 19315: 19125: 19105: 19065: 18897: 18717: 18460: 18220: 18036: 17445: 17414: 17362: 17257: 17207: 17192: 17187: 17162: 17157: 16965: 16921: 16734: 16344: 16324: 16289: 16041: 15283:"SpaceX's giant Starship will be 500 feet tall for Mars missions, Elon Musk says (video)" 14538:"Mars is littered with 15,694 pounds of human trash from 50 years of robotic exploration" 12262: 11826: 9828: 9033: 5074: 4869: 4357: 4210: 4062: 3840: 3274: 3093: 2826: 2771: 2561: 2416: 1857: 1508: 1404:; other common surface colors include golden, brown, tan, and greenish, depending on the 1235: 1189: 1141: 1071: 1016: 297: 246: 22634: 22513: 15327: 15239: 15000: 14905: 14868: 14773: 14742: 14673: 14425: 13944: 13729: 13686: 13324: 13180: 13083: 13004: 12959: 12436: 12352: 12134: 12079: 12071: 12014: 11937: 11870: 11790: 11609: 11594:"Hydrous melting of the martian mantle produced both depleted and enriched shergottites" 11301: 11245: 11163: 11086: 11041: 11028:

Craddock, R.A., Howard, A.D. (2002). "The case for rainfall on a warm, wet early Mars".

10990: 10902: 10778: 10616: 10529: 10361: 10195: 10125: 9944: 9883: 9738: 9680: 9610: 9518: 9467: 9309: 9256: 9103: 9031: 9008: 8930: 8837: 8555: 8498: 8434: 8384: 8135: 8101: 8054: 7694: 7642: 7499: 7454: 7411: 7284: 7232: 7171: 7116: 7057: 6949: 6909: 6882: 6866: 6812: 6768: 6709: 6658: 6623: 6568: 6523: 6447: 6411: 6376: 6360: 6294: 6020: 5973: 5861: 5731: 5686: 5648: 5596: 5557: 5315: 5167: 5124: 4916: 4798: 1924:", a zero-elevation surface had to be selected as a reference level; this is called the 1871: 1340: 23885: 23873: 23800: 23670: 23617: 23495: 23465: 23373: 23186: 22323: 22154: 21598: 21497: 21462: 21361: 21351: 21074: 20108: 20028: 20018: 19918: 19638: 19548: 19472: 19347: 19335: 19330: 19250: 19140: 19120: 19045: 18947: 18927: 17745: 17695: 17357: 17347: 17292: 17262: 17217: 17202: 17197: 17172: 16662: 16371: 16284: 16274: 16023: 15981: 15498: 15435:

Mesopotamian Astrology: An Introduction to Babylonian and Assyrian Celestial Divination

15347: 15022: 14940: 14754: 14728: 14701: 14685: 14537: 14005: 13956: 13913: 13861: 13698: 13344: 13166: 13095: 12954:. Concepts and Approaches for Mars Exploration. 12–14 June 2012. Houston, Texas. 4337. 12579: 12366: 12178: 12154: 12091: 12036: 11967: 11890: 11802: 11434: 11365: 11106: 11010: 10922: 10889:

Jaeger WL (21 September 2007). "Athabasca Valles, Mars: A Lava-Draped Channel System".

10871: 10808: 10636: 10573: 10557: 10219: 10145: 9982: 9969: 9928: 9897: 9870: 9809: 9752: 9700: 9630: 9538: 9487: 9329: 9278: 8892: 8849: 8766: 8575: 8518: 8357: 8324: 8257: 8208: 7978: 7916: 7825: 7714: 7511: 7486:

Kounaves SP (2010). "Soluble Sulfate in the Martian Soil at the Phoenix Landing Site".

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with an 84-centimetre (33 in) telescope, irregular patterns were observed, but no

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of water, and it is about 0.6% of the sea level surface pressure on Earth (0.006 atm).

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beside the Sun, arranged by the order of their orbits outward from the Sun (from left:

1345: 1185: 1087: 1004: 980: 850: 22607: 22570: 21279: 20283: 14959: 14750: 13034:

Compositional Interpretation of PFS/MEx and TES/MGS Thermal Infrared Spectra of Phobos

11898: 10513: 9664: 8485:

Schenk P (2012). "The Geologically Recent Giant Impact Basins at Vesta's South Pole".

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detected by Mars orbiters are both claimed to be possible evidence for life, as these

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in 2007 that indicated wet conditions in the past, and in December 2011, the mineral

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C. S. Lewis on the Final Frontier: Science and the Supernatural in the Space Trilogy

15078: 15026: 14758: 14705: 14154: 14009: 13917: 13798: 12562: 12299: 12158: 11971: 11921: 11894: 11806: 11438: 11110: 10875: 10577: 9772:"Day-night differences in Mars methane suggest nighttime containment at Gale crater" 9756: 9634: 9374:"The Mars Landing Approach: Getting Large Payloads to the Surface of the Red Planet" 9333: 7718: 7515: 7472: 7338: 7308: 7205: 6463: 5573: 5465:. Cambridge planetary science. Vol. 8. Cambridge University Press. p. 21. 5411: 5351: 5232: 4246:. Besides national space agencies and space companies, there are groups such as the 2778: 1705: 1223:-sized body about four billion years ago. The event, thought to be the cause of the 23721: 23525: 23515: 23408: 23383: 22793: 22763: 22614: 22488: 22328: 22193: 21850: 21798: 21630: 21016: 20490: 20388: 20363: 19993: 19988: 19923: 19898: 19893: 19863: 19853: 19843: 19698: 19628: 19563: 19497: 19412: 19295: 19225: 19180: 19170: 19135: 19095: 19060: 19055: 19040: 19015: 18990: 18975: 18862: 18772: 18667: 18565: 18485: 18465: 18420: 18388: 18195: 18160: 18140: 18098: 17919: 17799: 17789: 17565: 17547: 17475: 17465: 17409: 17387: 16899: 16824: 16481: 16463: 16448: 16408: 16319: 16231: 15891: 15480: 15472: 15351: 15339: 15331: 15243: 15012: 15004: 14932: 14909: 14892: 14872: 14746: 14677: 14280:"As new probes reach Mars, here's what we know so far from trips to the red planet" 13987: 13948: 13897: 13690: 13573: 13328: 13087: 13008: 12440: 12356: 12138: 12075: 12018: 11949: 11941: 11874: 11794: 11613: 11410: 11305: 11249: 11090: 11055: 11014: 10994: 10906: 10859: 10855: 10812: 10800: 10792: 10640: 10620: 10541: 10533: 10514:"Radar Sounding Evidence for Buried Glaciers in the Southern Mid-Latitudes of Mars" 10209: 10199: 10129: 10109: 9964: 9948: 9887: 9791: 9742: 9704: 9684: 9614: 9587: 9542: 9522: 9471: 9313: 9260: 9206: 9012: 8934: 8884: 8841: 8695: 8579: 8559: 8542: 8502: 8438: 8192: 8139: 8058: 7960: 7698: 7646: 7621: 7503: 7458: 7288: 7246: 7185: 7120: 7061: 6953: 6904: 6894: 6886: 6816: 6772: 6723: 6713: 6670: 6662: 6627: 6580: 6572: 6535: 6527: 6451: 6406: 6388: 6380: 6358: 6306: 6298: 6198: 6108: 6036: 6024: 5977: 5865: 5727: 5670: 5652: 5600: 5561: 5458: 5399: 5329: 5319: 5171: 5128: 5033: 4970: 4962: 4920: 4802: 4725: 4393:, in which human explorers accidentally destroy a Martian civilization; as well as 4303: 4085: 4053: 3916: 3909: 3853: 3303: 3245: 3221: 3077: 3018: 2821: 2687: 2670: 2542: 2125: 2111: 1906: 1733:

per day during the flight to and from Mars. For comparison the radiation levels in

1694: 1500: 1381: 1352: 1309: 1289: 1258:, orbiting Mars billions of years ago; and Phobos would be a remnant of that ring. 1126: 1122: 1059: 877: 752: 585: 331: 110: 72: 33: 18622: 12687: 12142: 11094: 10846:

Kerr RA (4 March 2005). "Ice or Lava Sea on Mars? A Transatlantic Debate Erupts".

10486: 9796: 9771: 8161: 7562:"Mars covered in toxic chemicals that can wipe out living organisms, tests reveal" 5543: 4730: 4705: 4314:, deity of war and destruction. It persisted into modern times, as exemplified by 1038:

in northern parts of Mars strongly contrast with the cratered terrain in southern

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rock discovered on Mars in June 2024 has been designated by NASA as a "potential

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In November 2016, NASA reported finding a large amount of underground ice in the

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has the lowest surface radiation at about 0.342 millisieverts per day, featuring

1742: 1734: 1661: 1636: 1524:; instead, below 1050 km in depth, it becomes mineralogically similar to Earth's 1457: 1449: 1416: 1393: 1335: 1317: 1283: 1063: 984: 947: 836: 714: 617: 578: 16976: 14681: 12416: 7592: 7266:"Morphology and Composition of the Surface of Mars: Mars Odyssey THEMIS Results" 5425: 5403: 4192: 3076:(VNIR) spectra of the moons of Mars resemble those of outer-belt asteroids, the 2863: 2208:

4 billion years ago, possibly because of numerous asteroid strikes, so the

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The Japanese Numbers Game: The Use and Understanding of Numbers in Modern Japan

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Hassler DM, Zeitlin C, Wimmer-Schweingruber RF, et al. (24 January 2014).

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25 times brighter than any observed earlier, due to a massive, and unexpected,

2364: 2272: 2147: 2069: 2049:. If this is the case, the Northern Hemisphere of Mars would be the site of an 2002: 1884: 1750: 1647: 1597: 1445: 1228: 1079: 996: 923: 255: 222: 102: 96: 64: 20539: 11945: 10133: 8699: 8196: 7964: 7795:"Comparison of Martian Radiation Environment with International Space Station" 7733: 7702: 6777: 6752: 6361:"Geophysical evidence for an enriched molten silicate layer above Mars's core" 6028: 5565: 5132: 4975: 4966: 4807: 4782: 3873: 3051:

The origin of the two satellites is not well understood. Their low albedo and

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resulting from precipitation in early Mars history. Subsurface water flow and

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for the definition of 0.0° longitude to coincide with the original selection.

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Religion in China – Universism: A Key to the Study of Taoism and Confucianism

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Samuel H, Drilleau, Mélanie, Rivoldini, Attilio, et al. (October 2023).

6261: 5879: 5251: 5140: 5047: 4984: 4647: 4172: 4119: 4105: 4081: 4058: 3930: 3363: 3332: 3194:(from the Arabic for "greatest"), which became the authoritative treatise on 2991: 2987: 2973: 2949: 2932: 2928: 2924: 2802: 2765: 2753: 2697: 2576: 2538: 2475: 2406:

when it is summer in its southern hemisphere and winter in its northern, and

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clearly visible from Earth. There are other notable impact features, such as

2050: 2017: 1935: 1861: 1853: 1738: 1665: 1385: 1273: 1255: 1239: 1083: 1028: 1024: 1020: 902: 822: 398: 394: 390: 274: 15728: 15343: 15017: 13952: 13534: 12390:(illustrated ed.). Springer Science & Business Media. p. 600. 11878: 10910: 10804: 10654: 10624: 10537: 9618: 9526: 9475: 9317: 8506: 8143: 8062: 8007: 7765:"Radiation on Mars 'Manageable' for Manned Mission, Curiosity Rover Reveals" 7292: 7189: 6934:"Spin state and deep interior structure of Mars from InSight radio tracking" 6820: 6302: 6087:"Mars: recent geological activity : Mars: a geologically active planet" 5981: 5324: 5299: 5038: 3640:. Coloring of the base map indicates relative elevations of Martian surface. 3206:

cultures, Mars is traditionally referred to as the "fire star" based on the

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and water. The atmosphere is quite dusty, containing particulates about 1.5

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Peplow M (25 February 2005). "Formaldehyde claim inflames Martian debate".

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Civilized Life in the Universe: Scientists on Intelligent Extraterrestrials

13791: 13030: 12150: 11886: 11430: 11102: 11006: 10918: 10867: 10632: 10569: 9978: 9696: 9626: 9534: 9483: 9325: 8571: 8514: 7876:"Planetary Names: Categories for Naming Features on Planets and Satellites" 7710: 7300: 7197: 7132: 7073: 7013: 6973: 6918: 6828: 6737: 6420: 6320: 5343: 5297: 4457: 4428: 4384: 4315: 4300: 4278: 4247: 4176: 4161: 4153: 4030: 3740: 3733: 3505: 3476: 2953: 2853: 2742: 2717: 2627: 2313: 2261: 2253: 2228: 2134: 2005: 1990: 1943: 1833: 1828: 1803: 1560: 1521: 1488:. Mars is confirmed to be seismically active; in 2019 it was reported that 1401: 1297: 1293: 1134: 1117:

period (3.5 to 3.3–2.9 billion years ago) was dominated by widespread

1106: 1075: 1051: 1008: 68: 20733: 15950: 15382:"To Prepare For Mars Settlement, Simulated Missions Explore Utah's Desert" 14936: 13466: 12984: 12240: 9892: 9865: 5895:"Researchers Find New Evidence that Mars Once Had Massive Ring | Sci.News" 4126:

may have found life. A 2014 analysis of Martian meteorite EETA79001 found

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formed during this period, with lava flows elsewhere on Mars. Named after

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Swerdlow NM (1998). "Periodicity and Variability of Synodic Phenomenon".

13013: 12986: 12431:(6). American Institute of Aeronautics and Astronautics (AIAA): 776–783. 11310: 11285: 11254: 11059: 10796: 10204: 10179: 9747: 9722: 9099: 8537: 8443: 8418: 7787: 7651: 7507: 7463: 7438: 7250: 6666: 6576: 6531: 6202: 5836:"Evidence for a Past Martian Ring from the Orbital Inclination of Deimos" 5700:

Nesvorný D (June 2018). "Dynamical Evolution of the Early Solar System".

4435:, and has continued as part of popular culture to the present. After the 4404: 4383:, in which Martians seek to escape their dying planet by invading Earth; 4374: 4320: 4288: 4131: 3465: 3395: 3241: 3217: 3177: 3045: 2734: 2595: 2572: 2175: 2107: 1897:

provided extensive imagery of Mars in 1972, a small crater (later called

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have been found. Much of the surface is deeply covered by finely grained

1529: 1516: 1452:, and a maximum thickness of 117 kilometres (73 mi) in the southern 1247: 1105:

period (4.5 to 3.5 billion years ago), Mars's surface was marked by

953: 787: 768: 758: 730: 21680: 15682: 14589:"NASA Selects Commercial Service Studies to Enable Mars Robotic Science" 11954: 11414: 10998: 10561: 10214: 9688: 8663: 8563: 6585: 1957:, each named for a classical albedo feature it contains. In April 2023, 23813: 23760: 23500: 23079: 22663: 22093: 22030: 21552: 21532: 21447: 21391: 21386: 21356: 21198: 20767: 20678: 18842: 18702: 18545: 18440: 18368: 18358: 18323: 18273: 18066: 17665: 16764: 16749: 16084: 16014: 15704: 14826:"Gilbert V. Levin, Who Said He Found Signs of Life on Mars, Dies at 97" 14689: 13432:. Vol. 2 (3rd ed.). Cambridge University Press. p. 187. 12531: 11399:"Jarosite as an indicator of water-limited chemical weathering on Mars" 11283: 10545: 9135: 8910: 8888: 8845: 6631: 5604: 5334: 4452:

knowledge of Mars became itself a source of inspiration for works like

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Researchers suspect much of the low northern plains of the planet were

2435: 2300: 2213: 2209: 2171: 2025: 1939: 1934:. Zero altitude was defined by the height at which there is 610.5 1716: 1205: 1197: 1133:. Due to Mars's geological history, the possibility of past or present 1095: 697: 483: 15335: 15167:"Independent report concludes 2033 human Mars mission is not feasible" 12948:

Use of MRO Optical Navigation Camera to Prepare for Mars Sample Return

10073:"NASA Spacecraft Detects Aurora and Mysterious Dust Cloud around Mars" 9265: 9240: 7681:

Gánti, Tibor (2003). "Dark Dune Spots: Possible Biomarkers on Mars?".

5587:

Zharkov VN (1993). "The role of Jupiter in the formation of planets".

5012:"Constraints on the pre-impact orbits of Solar system giant impactors" 4780: 23932: 23774: 23767: 23196: 23162: 22993: 22914: 22837: 22832: 22803: 22550: 22503: 22372: 22355: 22015: 21658: 21472: 21432: 21212: 21193: 21178: 21130: 21031: 20853: 20780: 20712: 18318: 17909: 17715: 17570: 16916: 16852: 16486: 16349: 15008: 13992: 13975: 11798: 11617: 10180:"Global Aurora on Mars During the September 2017 Space Weather Event" 7830: 7531:"Toxic Mars: Astronauts Must Deal with Perchlorate on the Red Planet" 4529: 4165: 3968: 3625: 3595: 3535: 3344: 3283: 3173: 3114: 3081: 2942: 2725: 2369: 2009: 1967:. A related, but much more detailed, global Mars map was released by 1921: 1893: 1888: 1746: 1686: 1678: 1624: 1612: 1578: 1493: 1485: 1477: 1473: 1279: 1146: 1118: 1114: 1101:

Mars was formed approximately 4.5 billion years ago. During the

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of about 0.09; of the seven other planets in the Solar System, only

2076:, which is around 1,800 kilometres (1,100 mi) in diameter, and 23827: 23665: 23132: 22988: 22973: 22714: 22421: 22269: 21924: 21808: 21457: 21437: 21427: 21304: 21261: 21004: 20981: 20974: 20899: 20894: 20881: 20874: 19788: 17833: 17575: 16926: 16638: 16619: 16491: 15960: 14187:"New Online Tools Bring NASA's Journey to Mars to a New Generation" 14135: 13901: 12444: 10237:

Webster G, Neal-Jones N, Scott J, et al. (29 September 2017).

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Brown D, Neal-Jones N, Steigerwald B, et al. (18 March 2015).

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Le Maistre S, Rivoldini A, Caldiero A, et al. (14 June 2023).

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Mars has two relatively small (compared to Earth's) natural moons,

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to transfer between Mars and Earth is the second lowest for Earth.

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Mars's equator is defined by its rotation, but the location of its

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Andert TP, Rosenblatt, P., Pätzold, M., et al. (7 May 2010).

12334: 9829:"NASA Mission Provides Its First Look at Martian Upper Atmosphere" 9505:

Lemmon MT (2004). "Atmospheric Imaging Results from Mars Rovers".

8122:, Sturms FM Jr (1973), "Mariner 9 Areographic Coordinate System", 7219:

Bandfield JL (June 2002). "Global mineral distributions on Mars".

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is 96,000 Earth years compared to Earth's cycle of 100,000 years.

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