From HandWiki
Short description: Planet

Mars ♂
Mars appears as a red-orange globe with darker blotches and white icecaps visible on both of its poles.
Pictured in natural color in 2007[lower-alpha 1]
Orbital characteristics[5]
Epoch J2000
|{{{apsis}}}|helion}}249261000 km
(154884000 mi; 1.66621 AU)[1]
|{{{apsis}}}|helion}}206650000 km
(128410000 mi; 1.3814 AU)[1]
227939366 km
(141634956 mi; 1.52368055 AU)[2]
Orbital period686.980 d
(1.88085 yr; 668.5991 sols)[1]
Synodic period779.94 d
(2.1354 yr)[2]
Average Orbital speed24.07 km/s
(86700 km/h; 53800 mph)[1]
Mean anomaly19.412°[1]
Longitude of ascending node49.57854°[1]
Physical characteristics
Mean radius3389.5 ± 0.2 km[lower-alpha 2][6]
(2106.1 ± 0.1 mi)
equatorial radius]]3396.2 ± 0.1 km[lower-alpha 2][6]
(2110.3 ± 0.1 mi; 0.533 Earths)
Polar radius3376.2 ± 0.1 km[lower-alpha 2][6]
(2097.9 ± 0.1 mi; 0.531 Earths)
Surface area144.37×106 km2[7]
(5.574×107 sq mi; 0.284 Earths)
Volume1.63118×1011 km3[8]
(0.151 Earths)
Mass6.4171×1023 kg[9]
(0.107 Earths)
Mean density3.9335 g/cm3[8]
(0.1421 lb/cu in)
3.72076 m/s2[10]
(12.2072 ft/s2; 0.3794 g)
inertia factor0.3644±0.0005[9]
5.027 km/s
(18100 km/h; 11250 mph)[11]
Rotation period1.02749125 d[12]
 24h 39m 36s
Sidereal rotation period1.025957 d
 24h 37m 22.7s[8]
Equatorial rotation velocity241 m/s
(870 km/h; 540 mph)[1]
Axial tilt25.19° to its orbital plane[1]
North pole right ascension317.68143°[6]
 21h 10m 44s
North pole declination52.88650°[6]
Surface temp. min mean max
Celsius −110 °C[15] −60 °C[16] 35 °C[15]
Fahrenheit −166 °F[15] −80 °F[16] 95 °F[15]
Apparent magnitude−2.94 to +1.86[14]
Angular diameter3.5–25.1″[1]
Surface pressure0.636 (0.4–0.87) kPa
0.00628 atm

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being larger than only Mercury. In English, Mars carries the name of the Roman god of war. Mars is a terrestrial planet with a thin atmosphere, and has a crust primarily composed of elements similar to Earth's crust, as well as a core made of iron and nickel. Mars has surface features such as impact craters, valleys, dunes, and polar ice caps. It also has two small and irregularly shaped moons, Phobos and Deimos.

Some of the most notable surface features on Mars include Olympus Mons, the largest volcano and highest known mountain on any Solar System planet, and Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the Northern Hemisphere covers 40% of the planet and may be a giant impact feature.[17] The days and seasons on Mars are comparable to those of Earth as the planets have a similar rotation period and tilt of the rotational axis relative to the ecliptic plane. Liquid water on the surface of Mars cannot exist due to low atmospheric pressure, which is less than 1% of the atmospheric pressure on Earth.[18][19] Both of Mars's polar ice caps appear to be made largely of water.[20][21] Multiple lines of evidence suggest that Mars was wetter in the distant past, and thus possibly more suited for life. However, whether life ever did exist there, and if it could have survived to the present day, remain unanswered questions.

Mars has been explored by several uncrewed spacecraft, beginning with Mariner 4 in 1965. NASA's Viking 1 lander transmitted the first images from the Martian surface in 1976. Two countries have successfully deployed rovers on Mars, the United States first doing so with Sojourner in 1997 and China with Zhurong in 2021.[22] There are also planned future missions to Mars, such as a Mars sample-return mission set to happen in 2026, and the Rosalind Franklin rover mission, which was intended to launch in 2018 but was delayed to 2024.

Mars can easily be seen from Earth with the naked eye, as can its striking reddish coloring. This appearance, due the iron oxide prevalent on its surface, has led to Mars often being called the Red Planet.[23][24] It is among the brightest objects in Earth's sky, with an apparent magnitude that reaches −2.94, comparable to that of Jupiter and surpassed only by Venus, the Moon and the Sun.[14] Historically, Mars has been observed since ancient times, and over the millennia, has been featured in culture and the arts in ways that have reflected humanity's growing knowledge of it.

Physical characteristics

Mars is approximately half the diameter of Earth, with a surface area only slightly less than the total area of Earth's dry land.[1] Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. The red-orange appearance of the Martian surface is caused by iron(III) oxide, or rust.[25] It can look like butterscotch;[26] other common surface colors include golden, brown, tan, and greenish, depending on the minerals present.[26]

Internal structure

Like Earth, Mars has differentiated into a dense metallic core overlaid by less dense materials.[27][28] Current models of its interior imply a core consisting primarily of iron and nickel with about 16–17% sulfur.[29] This iron(II) sulfide core is thought to be twice as rich in lighter elements as Earth's.[30] The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but it appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminium, calcium, and potassium. The average thickness of the planet's crust is about 50 kilometres (31 mi), with a maximum thickness of 125 kilometres (78 mi).[30] By comparison, Earth's crust averages 40 kilometres (25 mi) in thickness.[31]

Mars is seismically active, with InSight detecting and recording over 450 marsquakes and related events in 2019.[32][33] In 2021 it was reported that based on eleven low-frequency Marsquakes detected by the InSight lander the core of Mars is indeed liquid and has a radius of about 1830±40 km and a temperature around 1900–2000 K. The Martian core radius is more than half the radius of Mars and about half the size of the Earth's core. This is somewhat larger than models predicted, suggesting that the core contains some amount of lighter elements like oxygen and hydrogen in addition to the iron–nickel alloy and about 15% of sulfur.[34][35]

Comparison: Earth and Mars
Animation (00:40) showing major features of Mars
Video (01:28) showing how three NASA orbiters mapped the gravity field of Mars

The core of Mars is overlain by the rocky mantle, which, however, does not seem to have a layer analogous to the Earth's lower mantle. The Martian mantle appears to be solid down to the depth of about 500 km, where the low-velocity zone (partially melted asthenosphere) begins.[36] Below the asthenosphere the velocity of seismic waves starts to grow again and at the depth of about 1050 km there lies the boundary of the transition zone.[35] At the surface of Mars there lies a crust with the average thickness of about 24–72 km.[37]

Surface geology

Main page: Astronomy:Geology of Mars

Mars is a terrestrial planet whose surface consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The Martian surface is primarily composed of tholeiitic basalt,[38] although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth, or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found.[39] Much of the surface is deeply covered by finely grained iron(III) oxide dust.[40]

Geologic map of Mars (USGS, 2014)[41]

Although Mars has no evidence of a structured global magnetic field,[42] 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 paleomagnetism of magnetically susceptible minerals is similar to the alternating bands found on Earth's ocean floors. One theory, published in 1999 and re-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands suggest plate tectonic activity on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic field faded.[43]

It is thought that, during the Solar System's formation, Mars was created as the result of a random process of run-away accretion of material from the protoplanetary disk 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 chlorine, phosphorus, and sulfur, are much more common on Mars than Earth; these elements were probably pushed outward by the young Sun's energetic solar wind.[44]

After the formation of the planets, all were subjected to the so-called "Late Heavy Bombardment". About 60% of the surface of Mars shows a record of impacts from that era,[45][46][47] whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. 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 South Pole – Aitken basin, the largest impact basin yet discovered.[48] This theory suggests that Mars was struck by a Pluto-sized body about four billion years ago. The event, thought to be the cause of the Martian hemispheric dichotomy, created the smooth Borealis basin that covers 40% of the planet.[49][50]

The geological history of Mars can be split into many periods, but the following are the three primary periods:[51][52]

  • Noachian period (named after Noachis Terra): 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 Tharsis bulge, a volcanic upland, is thought to have formed during this period, with extensive flooding by liquid water late in the period.[53]
  • Hesperian period (named after Hesperia Planum): 3.5 to between 3.3 and 2.9 billion years ago. The Hesperian period is marked by the formation of extensive lava plains.[53]
  • Amazonian period (named after Amazonis Planitia): between 3.3 and 2.9 billion years ago to the present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Olympus Mons formed during this period, with lava flows elsewhere on Mars.[53]

Geological activity is still taking place on Mars. The Athabasca Valles is home to sheet-like lava flows created about 200 Mya. Water flows in the grabens called the Cerberus Fossae occurred less than 20 Mya, indicating equally recent volcanic intrusions.[54] The Mars Reconnaissance Orbiter has captured images of avalanches.[55][56]


Main page: Astronomy:Martian soil

The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in soils on Earth, and they are necessary for growth of plants.[57] Experiments performed by the lander showed that the Martian soil has a basic pH of 7.7, and contains 0.6% of the salt perchlorate,[58][59] concentrations that are toxic to humans.[60][61]

Streaks 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 obstacles in their path. The commonly accepted theories include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils.[62] Several other explanations have been put forward, including those that involve water or even the growth of organisms.[63][64]


Main page: Astronomy:Water on Mars

Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% that of Earth's,[18] except at the lowest elevations for short periods.[28][65] The two polar ice caps appear to be made largely of water.[20][21] The volume of water ice in the south polar ice cap, if melted, would be enough to cover the entire surface of the planet with a depth of 11 metres (36 ft).[66] Large quantities of ice are thought to be trapped within the thick cryosphere of Mars. Radar data from Mars Express and the Mars Reconnaissance Orbiter (MRO) show large quantities of ice at both poles,[67][68] and at middle latitudes.[69] The Phoenix lander directly sampled water ice in shallow Martian soil on 31 July 2008.[70]

Landforms visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as outflow channels, 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.[71][72] One of the larger examples, Ma'adim Vallis, 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.[73] The youngest of these channels are thought to have formed as recently as only a few million years ago.[74] Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from precipitation in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.[75]

Along crater and canyon walls, there are thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the Southern Hemisphere and to 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,[76][77] although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust.[78][79] 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.[77] Other geological features, such as deltas and alluvial fans preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history.[80] Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence.[81]

A cross-section of underground water ice is exposed at the steep slope that appears bright blue in this enhanced-color view from the MRO.[82] The scene is about 500 meters wide. The scarp drops about 128 meters from the level ground. The ice sheets extend from just below the surface to a depth of 100 meters or more.[83]

Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water.[84] In 2004, Opportunity detected the mineral jarosite. This forms only in the presence of acidic water, which demonstrates that water once existed on Mars.[85][86] The Spirit rover found concentrated deposits of silica in 2007 that were also indicative of wet conditions in the past.[87] More recent evidence for liquid water comes from the finding of the mineral gypsum on the surface by NASA's Mars rover Opportunity in December 2011.[88][89] It is estimated that the amount of water in the upper mantle of Mars, represented by hydroxyl ions 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).[90][91]

On 18 March 2013, NASA reported evidence from instruments on the Curiosity rover of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock and "Sutton Inlier" rock as well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock.[92][93] Analysis using the rover's DAN instrument 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 Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain.[92] In September 2015, NASA announced that they had found strong evidence of hydrated brine flows in recurring slope lineae, based on spectrometer readings of the darkened areas of slopes.[94][95][96] These streaks flow downhill in Martian summer, when the temperature is above −23° Celsius, and freeze at lower temperatures.[97] 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.[98] 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.[99] A definitive conclusion about the presence, extent, and role of liquid water on the Martian surface remains elusive.[100][101]

Researchers suspect that much of the low northern plains of the planet were covered with an ocean hundreds of meters deep, though this remains controversial.[102] In March 2015, scientists stated that such an ocean might have been the size of Earth's Arctic Ocean. This finding was derived from the ratio of water to deuterium in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium is eight times the amount that exists on Earth, suggesting that ancient Mars had significantly higher levels of water. Results from the Curiosity rover had previously found a high ratio of deuterium in Gale Crater, 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.[103] Near the northern polar cap is the 81.4 kilometres (50.6 mi) wide Korolev Crater, which the Mars Express orbiter found to be filled with approximately 2,200 cubic kilometres (530 cu mi) of water ice.[104]

In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior.[105][106] During observations from 2018 through 2021, the ExoMars Trace Gas Orbiter spotted indications of water, probably subsurface ice, in the Valles Marineris canyon system.[107]

Polar caps

Main page: Astronomy:Martian polar ice caps
North polar early summer water ice cap (1999); a seasonal layer of carbon dioxide ice forms in winter and disappears in summer.

Mars has two permanent polar ice caps. During a pole's winter, it lies in continuous darkness, chilling the surface and causing the deposition of 25–30% of the atmosphere into slabs of CO2 ice (dry ice).[108] When the poles are again exposed to sunlight, the frozen CO2 sublimes. These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds. Clouds of water-ice were photographed by the Opportunity rover in 2004.[109]

The caps at both poles consist primarily (70%) of water ice. Frozen carbon dioxide accumulates as a comparatively thin layer about one metre thick on the north cap in the northern winter only, whereas the south cap has a permanent dry ice cover about eight metres thick. This permanent dry ice cover at the south pole is peppered by flat floored, shallow, roughly circular pits, which repeat imaging shows are expanding by meters per year; this suggests that the permanent CO2 cover over the south pole water ice is degrading over time.[110] The northern polar cap has a diameter of about 1,000 kilometres (620 mi),[111] and contains about 1.6 million cubic kilometres (5.7×1016 cu ft) of ice, which, if spread evenly on the cap, would be 2 kilometres (1.2 mi) thick.[112] (This compares to a volume of 2.85 million cubic kilometres (1.01×1017 cu ft) for the Greenland ice sheet.) The southern polar cap has a diameter of 350 kilometres (220 mi) and a thickness of 3 kilometres (1.9 mi).[113] The total volume of ice in the south polar cap plus the adjacent layered deposits has been estimated at 1.6 million cubic km.[114] Both polar caps show spiral troughs, which recent analysis of SHARAD ice penetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis effect.[115][116]

The seasonal frosting of areas near the southern ice cap results in the formation of transparent 1-metre-thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming CO2 builds up under a slab, elevating and ultimately rupturing it. This leads to geyser-like eruptions of CO2 gas mixed with dark basaltic sand or dust. This process is rapid, observed happening in the space of a few days, weeks or months, a rate of change rather unusual in geology – especially for Mars. The gas rushing underneath a slab to the site of a geyser carves a spiderweb-like pattern of radial channels under the ice, the process being the inverted equivalent of an erosion network formed by water draining through a single plughole.[117][118]

Geography and names

A MOLA-based topographic map showing highlands (red and orange) dominating the Southern Hemisphere of Mars, lowlands (blue) the northern. Volcanic plateaus delimit regions of the northern plains, whereas the highlands are punctuated by several large impact basins.
Terminology of Martian geological features
Terminology of Martian geological features

Although better remembered for mapping the Moon, Johann Heinrich Mädler and Wilhelm Beer 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.[119]

Features on Mars are named from a variety of sources. Albedo features 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 for the word "Mars" or "star" in various languages; small valleys are named for rivers.[120]

Large albedo features retain many of the older names but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus).[121] 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 Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum.[122] The permanent northern polar ice cap is named Planum Boreum, whereas the southern cap is called Planum Australe.[123]

Mars's equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line for their first maps of Mars in 1830. After the spacecraft Mariner 9 provided extensive imagery of Mars in 1972, a small crater (later called Airy-0), located in the Sinus Meridiani ("Middle Bay" or "Meridian Bay"), was chosen by Merton Davies, Harold Masursky, and Gérard de Vaucouleurs for the definition of 0.0° longitude to coincide with the original selection.[124][125][126]

Because Mars has no oceans and hence no "sea level", a zero-elevation surface had to be selected as a reference level; this is called the areoid[127] of Mars, analogous to the terrestrial geoid.[128] Zero altitude was defined by the height at which there is 610.5 Pa (6.105 mbar) of atmospheric pressure.[129] This pressure corresponds to the triple point of water, and it is about 0.6% of the sea level surface pressure on Earth (0.006 atm).[130]

For mapping purposes, the United States Geological Survey divides the surface of Mars into thirty cartographic quadrangles, each named for a classical albedo feature it contains.[131]

Impact topography

Fresh asteroid impact on Mars at 3°20′N 219°23′E / 3.34°N 219.38°E / 3.34; 219.38. These before and after images of the same site were taken on the Martian afternoons of 27 and 28 March 2012 respectively (MRO).[132]

The dichotomy 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 Moon. If this is the case, the Northern Hemisphere of Mars would be the site of an impact crater 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 Utopia Planitia and the Moon's South Pole–Aitken basin as the largest impact crater in the Solar System.[133][134][135]

Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of 5 kilometres (3.1 mi) or greater have been found.[136] The largest exposed crater is Hellas, which is 2,300 kilometres (1,400 mi) wide and 7,000 metres (23,000 ft) deep, and is a light albedo feature clearly visible from Earth.[137][138] There are other notable impact features, such as Argyre, which is around 1,800 kilometres (1,100 mi) in diameter,[139] and Isidis, which is around 1,500 kilometres (930 mi) in diameter.[140] 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 asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter.[141]

Martian craters can have a morphology that suggests the ground became wet after the meteor impacted.[142]


Main page: Astronomy:Volcanology of Mars
Viking 1 image of Olympus Mons. The volcano and related terrain are approximately 550 km (340 mi) across.

The shield volcano Olympus Mons (Mount Olympus) is an extinct volcano in the vast upland region Tharsis, which contains several other large volcanoes. The edifice is over 600 km (370 mi) wide.[143][144] Because the mountain is so large, with complex structure at its edges, allocating a 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),[144] a little over twice the height of Mauna Kea as measured from its base on the ocean floor. The total elevation change from the plains of Amazonis Planitia, over 1,000 km (620 mi) to the northwest, to the summit approaches 26 km (16 mi),[145] roughly three times the height of Mount Everest, which in comparison stands at just over 8.8 kilometres (5.5 mi). Consequently, Olympus Mons is either the tallest or second-tallest mountain in the Solar System; the only known mountain which might be taller is the Rheasilvia peak on the asteroid Vesta, at 20–25 km (12–16 mi).[146]

Tectonic sites

Valles Marineris (2001 Mars Odyssey)

The large canyon, Valles Marineris (Latin for "Mariner Valleys", also known as Agathodaemon in the old canal maps[147]), 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, the Grand Canyon 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 graben, but a plate boundary where 150 kilometres (93 mi) of transverse motion has occurred, making Mars a planet with possibly a two-tectonic plate arrangement.[148][149]


Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the volcano Arsia Mons.[150] The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters".[151] 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, it is possible that they 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, solar flares and high energy particles that bombard the planet's surface.[152][153]


Main page: Astronomy:Atmosphere of Mars
Escaping atmosphere on Mars (carbon, oxygen, and hydrogen) by MAVEN in UV[154]

Mars lost its magnetosphere 4 billion years ago,[155] possibly because of numerous asteroid strikes,[156] so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer.[157] Both Mars Global Surveyor and Mars Express have detected ionised atmospheric particles trailing off into space behind Mars,[155][158] and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of 30 Pa (0.0044 psi) on Olympus Mons to over 1,155 Pa (0.1675 psi) in Hellas Planitia, with a mean pressure at the surface level of 600 Pa (0.087 psi).[159] The highest atmospheric density on Mars is equal to that found 35 kilometres (22 mi)[160] above Earth's surface. The resulting mean surface pressure is only 0.6% of that of Earth 101.3 kPa (14.69 psi). The scale height of the atmosphere is about 10.8 kilometres (6.7 mi),[161] which is higher than Earth's 6 kilometres (3.7 mi), because the surface gravity of Mars is only about 38% of Earth's.[162]

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water.[1][163][157] The atmosphere is quite dusty, containing particulates about 1.5 µm in diameter which give the Martian sky a tawny color when seen from the surface.[164] It may take on a pink hue due to iron oxide particles suspended in it.[23] The concentration of methane in the Martian atmosphere fluctuates from about 0.24 ppb during the northern winter to about 0.65 ppb during the summer.[165] Estimates of its lifetime range from 0.6 to 4 years,[166][167] so its presence indicates that an active source of the gas must be present. Methane could be produced by non-biological process such as serpentinization involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars,[168] or by Martian life.[169]

Compared to Earth, its higher concentration of atmospheric CO2 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 Perseverance 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.[170][171]

Auroras have been detected on Mars.[172][173][174] Because Mars lacks a global magnetic field, the types and distribution of auroras there differ from those on Earth;[175] rather than being mostly restricted to polar regions, a Martian aurora can encompass the planet.[176] In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25 times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month.[176][177]


Main page: Astronomy:Climate of Mars

Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to the similar tilts of the two planets' rotational axes. The lengths of the Martian seasons are about twice those of Earth's because Mars's greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about −110 °C (−166 °F) to highs of up to 35 °C (95 °F) in equatorial summer.[15] The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil.[178] The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.[179][180]

If Mars had an Earth-like orbit, its seasons would be similar to Earth's because its axial tilt is similar to Earth's. The comparatively large eccentricity of the Martian orbit has a significant effect. Mars is near perihelion when it is summer in the Southern Hemisphere and winter in the north, and near aphelion when it is winter in the Southern Hemisphere and summer in the north. As a result, the seasons in the Southern Hemisphere are more extreme and the seasons in the northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to 30 °C (54 °F).[181]

Mars has the largest dust storms 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 the global temperature.[182]

Dust storms on Mars
18 November 2012
25 November 2012
Locations of the Opportunity and Curiosity rovers are noted

Orbit and rotation

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 sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds.[184] A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours.[1]

The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth.[1] As a result, Mars has seasons like Earth, though on Mars they are nearly twice as long because its orbital period is that much longer. In the present day epoch, the orientation of the north pole of Mars is close to the star Deneb.[185]

Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planets in the Solar System, only Mercury 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.[186] Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years.[187]

Habitability and search for life

Viking 1 lander's sampling arm scooped up soil samples for tests (Chryse Planitia)

During the late nineteenth century, it was widely accepted in the astronomical community that Mars had life-supporting qualities, including oxygen and water. However, in 1894 W. W. Campbell at Lick Observatory 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 V. M. Slipher repeated the study in 1909 using better instruments, but with the same results. It wasn't until the findings were confirmed by W. S. Adams in 1925 that the myth of the Earth-like habitability of Mars was finally broken.[188] However, even in the 1960s, articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars. Detailed scenarios for the metabolism and chemical cycles for a functional ecosystem were being published as late as 1962.[189]

The current understanding of planetary habitability – 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 habitable zone, which for the Sun is estimated to extend from within the orbit of Earth to about that of Mars.[190] 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.[191]

The lack of a magnetosphere and the extremely thin atmosphere of Mars are a challenge: the planet has little heat transfer across its surface, poor insulation against bombardment of the solar wind and insufficient atmospheric pressure to retain water in a liquid form (water instead sublimes 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.[192]

In situ investigations have been performed on Mars by the Viking landers, Spirit and Opportunity rovers, Phoenix lander, and Curiosity rover. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. The Viking probes 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 of CO
production on exposure to water and nutrients. This sign of life was later disputed by scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life.[193] Tests conducted by the Phoenix Mars lander have shown that the soil has an alkaline pH and it contains magnesium, sodium, potassium and chloride.[194] The soil nutrients may be able to support life, but life would still have to be shielded from the intense ultraviolet light.[195] A 2014 analysis of Martian meteorite EETA79001 found chlorate, perchlorate, and nitrate ions in sufficiently high concentration to suggest that they are widespread on Mars. UV and X-ray radiation would turn chlorate and perchlorate ions into other, highly reactive oxychlorines, indicating that any organic molecules would have to be buried under the surface to survive.[196]

Scientists have proposed that carbonate globules found in meteorite ALH84001, which is thought to have originated from Mars, could be fossilized microbes extant on Mars when the meteorite was blasted from the Martian surface by a meteor strike some 15 million years ago. This proposal has been met with skepticism, and an exclusively inorganic origin for the shapes has been proposed.[197] Small quantities of methane and formaldehyde detected by Mars orbiters are both claimed to be possible evidence for life, as these chemical compounds would quickly break down in the Martian atmosphere.[198][199] Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinite.[168] Impact glass, 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.[200][201] Likewise, the glass in impact craters on Mars could have preserved signs of life, if life existed at the site.[202][203][204]


Main pages: Astronomy:Moons of Mars, Astronomy:Phobos (moon), and Astronomy:Deimos (moon)
Enhanced-color HiRISE image of Phobos, showing a series of mostly parallel grooves and crater chains, with Stickney crater at right
Enhanced-color HiRISE image of Deimos (not to scale), showing its smooth blanket of regolith

Mars has two relatively small (compared to Earth's) natural moons, Phobos (about 22 kilometres (14 mi) in diameter) and Deimos (about 12 kilometres (7.5 mi) in diameter), which orbit close to the planet. Asteroid capture is a long-favored theory, but their origin remains uncertain.[205] Both satellites were discovered in 1877 by Asaph Hall; they are named after the characters Phobos (panic/fear) and Deimos (terror/dread), who, in Greek mythology, accompanied their father Ares, god of war, into battle.[206] Mars was the Roman equivalent to Ares.[207] In modern Greek, the planet retains its ancient name Ares (Aris: Άρης).[134]

From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbit – where the orbital period would match the planet's period of rotation – rises as expected in the east but slowly.

Because the orbit of Phobos is below synchronous altitude, the tidal forces from the planet 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.[208]

The origin of the two moons is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as similar to asteroids, supporting the capture theory. The unstable orbit of Phobos would seem to point towards a relatively recent capture. But both have circular orbits, 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.[209]

A third possibility 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,[210] and suggesting a composition containing mainly phyllosilicates and other minerals known from Mars,[211] point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's moon. Although the visible and near-infrared (VNIR) spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class.[211] It is also possible that Phobos and Deimos are fragments of an older moon, formed by debris from a large impact on Mars, and then destroyed by a more recent impact upon itself.[212]

Mars may have 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.[213]


Main page: Astronomy:Exploration of Mars
The descent stage of the Mars Science Laboratory mission carrying the Curiosity rover deploys its parachutes to decelerate itself before landing, photographed by Mars Reconnaissance Orbiter.

Dozens of crewless spacecraft, including orbiters, landers, and rovers, have been sent to Mars by the Soviet Union, the United States, Europe, India, the United Arab Emirates, and China to study the planet's surface, climate, and geology.[214] NASA's Mariner 4 was the first spacecraft to visit Mars; launched on 28 November 1964, it made its closest approach to the planet on 15 July 1965. Mariner 4 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.[215]

Once spacecraft visited the planet during NASA's Mariner missions in the 1960s and 1970s, many previous concepts of Mars were radically broken. After the results of the Viking life-detection experiments, the hypothesis of a hostile, dead planet was generally accepted.[216] The data from Mariner 9 and Viking allowed better maps of Mars to be made, and the Mars Global Surveyor mission, which launched in 1996 and operated until late 2006, produced complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals.[217] These maps are available online at websites including Google Mars. Both the Mars Reconnaissance Orbiter and Mars Express 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 Experience Curiosity, which simulates traveling on Mars in 3-D with Curiosity.[218][219]

(As of 2021), Mars is host to fourteen functioning spacecraft. Eight are in orbit: 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN, Mars Orbiter Mission, ExoMars Trace Gas Orbiter, the Hope orbiter, and the Tianwen-1 orbiter.[220][221] Another six are on the surface: the InSight lander,[222] the Mars Science Laboratory Curiosity rover, the Perseverance rover, the Ingenuity helicopter, the Tianwen-1 lander, and the Zhurong rover.[223]

The Rosalind Franklin rover mission, designed to search for evidence of past life, was intended to be launched in 2018 but has been repeatedly delayed, with a launch date pushed to 2024 at the earliest.[224][225][226] The current concept for the Mars sample-return mission would launch in 2026 and feature hardware built by NASA and ESA.[227][228] Several plans for a human mission to Mars 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.[229][230] In addition, in 2021, China was planning to send a crewed Mars mission in 2033.[231]

Astronomy on Mars

Main page: Astronomy:Astronomy on Mars

With the presence of various orbiters, landers, and rovers, it is possible to practice astronomy from Mars. Although Mars's moon Phobos appears about one-third the angular diameter of the full moon on Earth, Deimos appears more or less star-like, looking only slightly brighter than Venus does from Earth.[232]

Various phenomena seen from Earth have also been observed from Mars, such as meteors and auroras.[233] The apparent sizes of the moons Phobos and Deimos are sufficiently smaller than that of the Sun; thus, their partial "eclipses" of the Sun are best considered transits (see transit of Deimos and Phobos from Mars).[234][235] Transits of Mercury and Venus have been observed from Mars. A transit of Earth will be seen from Mars on 10 November 2084.[236]

Earth and the Moon (MRO HiRISE, November 2016)[237]
Phobos transits the Sun (Opportunity, 10 March 2004)
Tracking sunspots from Mars


Animation of the apparent retrograde motion of Mars in 2003 as seen from Earth.

The mean apparent magnitude of Mars is +0.71 with a standard deviation of 1.05.[14] Because the orbit of Mars is eccentric, the magnitude at opposition from the Sun can range from about −3.0 to −1.4.[238] The minimum brightness is magnitude +1.86 when the planet is near aphelion and in conjunction with the Sun.[14] At its brightest, Mars (along with Jupiter) is second only to Venus in luminosity.[14] 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.[239] As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping curve with respect to the background stars. This retrograde motion lasts for about 72 days, and Mars reaches its peak luminosity in the middle of this interval.[240]

Mars distance from Earth in millions of km (Gm).

The point at which Mars's geocentric longitude is 180° different from the Sun's is known as opposition, which is near the time of closest approach to Earth. The time of opposition can occur as much as 8.5 days away from the closest approach. The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable variation in angular size.[241][242] The most recent Mars opposition occurred on 13 October 2020, at a distance of about 63 million km (39 million mi).[243] The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between the dates of successive oppositions can range from 764 to 812.[187]

Mars comes into opposition from Earth every 2.1 years. The planets come into opposition near Mars's perihelion in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition.[244][245] Mars made its closest approach to Earth and maximum apparent brightness in nearly 60,000 years, 55,758,006 km (0.37271925 AU; 34,646,419 mi), magnitude −2.88, on 27 August 2003, at 09:51:13 UTC. This occurred when Mars was one day from opposition and about three days from its perihelion, making it particularly easy to see from Earth. The last time it came so close is estimated to have been on 12 September 57,617 BC, the next time being in 2287.[246] This record approach was only slightly closer than other recent close approaches.[187]

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.[247]

Historical observations

Main page: Astronomy:History of Mars observation

The history of observations of Mars is marked by the 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 perihelic oppositions of Mars, which are distinguished because Mars is close to perihelion, making it even closer to Earth.[244]

Ancient and medieval observations

The ancient Sumerians believed that Mars was Nergal, 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 Nineveh.[248] In Mesopotamian texts, Mars is referred to as the "star of judgement of the fate of the dead."[249] The existence of Mars as a wandering object in the night sky was also recorded by the ancient Egyptian astronomers and, by 1534 BCE, they were familiar with the retrograde motion of the planet.[250] By the period of the Neo-Babylonian Empire, the Babylonian astronomers 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 synodic periods, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets.[251][252] In Ancient Greece , the planet was known as Ancient Greek:.[253]

In the fourth century BCE, Aristotle noted that Mars disappeared behind the Moon during an occultation, indicating that the planet was farther away.[254] Ptolemy, a Greek living in Alexandria,[255] 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 Almagest (from the Arabic for "greatest"), which became the authoritative treatise on Western astronomy for the next fourteen centuries.[256] Literature from ancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE.[257] In the East Asian cultures, Mars is traditionally referred to as the "fire star" (Chinese: 火星), based on the Wuxing system.[258][259][260]

During the seventeenth century, Tycho Brahe measured the diurnal parallax of Mars that Johannes Kepler used to make a preliminary calculation of the relative distance to the planet.[261] From Brahe's observations of Mars, Kepler deduced that the planet orbited the Sun not in a circle, but in an ellipse. Moreover, Kepler showed that Mars sped up as it approached the Sun and slowed down as it moved farther away, in a manner that later physicists would explain as a consequence of the conservation of angular momentum.[262](pp433–437) 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 Giovanni Domenico Cassini in 1672. The early parallax measurements were hampered by the quality of the instruments.[263] The only occultation of Mars by Venus observed was that of 13 October 1590, seen by Michael Maestlin at Heidelberg.[264] In 1610, Mars was viewed by Italian astronomer Galileo Galilei, who was first to see it via telescope.[265] The first person to draw a map of Mars that displayed any terrain features was the Dutch astronomer Christiaan Huygens.[266]

Martian "canals"

Main page: Astronomy:Martian canal
Map of Mars by Giovanni Schiaparelli
Mars sketched as observed by Lowell before 1914 (south on top)

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 of Mars occurred. During that day, the Italian astronomer Giovanni Schiaparelli used a 22-centimetre (8.7 in) telescope in Milan to help produce the first detailed map of Mars. These maps notably contained features he called canali, which were later shown to be an optical illusion. These canali 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".[267][268]

Influenced by the observations, the orientalist Percival Lowell founded an observatory 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 public.[269][270] The canali were independently observed by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time.[271][272]

The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summer) 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, fewer long, straight canali were observed. During observations in 1909 by Antoniadi with an 84-centimetre (33 in) telescope, irregular patterns were observed, but no canali were seen.[273]

In culture

Martian tripod illustration from the 1906 French edition of The War of the Worlds by H. G. Wells

Mars is named after the Roman god of war. This association between Mars and war dates back at least to Babylonian astronomy, in which the planet was named for the god Nergal, deity of war and destruction.[274][275] It persisted into modern times, as exemplified by Gustav Holst's orchestral suite The Planets, whose famous first movement labels Mars "the bringer of war".[276] The planet's symbol, a circle with a spear pointing out to the upper right, is also used as a symbol for the male gender.[277] The symbol dates from at latest the 11th century, though a possible predecessor has been found in the Greek Oxyrhynchus Papyri.[278]

The idea that Mars was populated by intelligent Martians became widespread in the late 19th century. Schiaparelli's "canali" observations combined with Percival Lowell'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.[279] Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever".[280] 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 canali observations, these speculations are based on small scale features perceived in the spacecraft images, such as "pyramids" and the "Face on Mars".[281] In his book Cosmos, planetary astronomer Carl Sagan wrote: "Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears."[268]

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.[282] This gave way to many science fiction stories involving these concepts, such as H. G. Wells' The War of the Worlds, in which Martians seek to escape their dying planet by invading Earth, Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization, as well as Edgar Rice Burroughs' Barsoom series, C. S. Lewis' novel Out of the Silent Planet (1938),[283] and a number of Robert A. Heinlein stories before the mid-sixties.[284] Since then, depictions of Martians have also extended to animation. A comic figure of an intelligent Martian, Marvin the Martian, appeared in Haredevil Hare (1948) as a character in the Looney Tunes animated cartoons of Warner Brothers, and has continued as part of popular culture to the present.[285] After the Mariner and Viking spacecraft had returned pictures of Mars as it really is, 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 post-Viking knowledge of Mars became itself a source of inspiration for works like Kim Stanley Robinson's Mars trilogy.[286]

See also


  1. This image was taken by the Rosetta spacecraft's Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), at a distance of ≈240,000 kilometres (150,000 mi) during its February 2007 encounter. The view is centered on the Aeolis quadrangle, with Gale crater, the landing site of the Curiosity rover, prominently visible just left of center. The darker, more heavily cratered terrain in the south, Terra Cimmeria, is composed of older terrain than the much smoother and brighter Elysium Planitia to the north. Geologically recent processes, such as the possible existence of a global ocean in Mars's past, could have helped lower-elevated areas, such as Elysium Planitia, retain a more youthful look.
  2. 2.0 2.1 2.2 Best-fit ellipsoid


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Williams, David (2018). "Mars Fact Sheet". NASA Goddard Space Flight Center. ; Mean Anomaly (deg) 19.412 = (Mean Longitude (deg) 355.45332) – (Longitude of perihelion (deg) 336.04084) This article incorporates text from this source, which is in the public domain.
  2. 2.0 2.1 2.2 Allen, Clabon Walter; Cox, Arthur N. (2000) (in en). Allen's Astrophysical Quantities. Springer Science & Business Media. pp. 294. ISBN 978-0-387-95189-8. 
  3. Souami, D.; Souchay, J. (July 2012). "The solar system's invariable plane". Astronomy & Astrophysics 543: 11. doi:10.1051/0004-6361/201219011. A133. Bibcode2012A&A...543A.133S. 
  4. 4.0 4.1 "HORIZONS Batch call for 2022 perihelion". Solar System Dynamics Group, Jet Propulsion Laboratory. 
  5. Simon, J.L.; Bretagnon, P.; Chapront, J.; Chapront-Touzé, M.; Francou, G.; Laskar, J. (February 1994). "Numerical expressions for precession formulae and mean elements for the Moon and planets". Astronomy and Astrophysics 282 (2): 663–683. Bibcode1994A&A...282..663S. 
  6. 6.0 6.1 6.2 6.3 6.4 6.5 Seidelmann, P. Kenneth; Archinal, Brent A.; A'Hearn, Michael F. et al. (2007). "Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006". Celestial Mechanics and Dynamical Astronomy 98 (3): 155–180. doi:10.1007/s10569-007-9072-y. Bibcode2007CeMDA..98..155S. 
  7. Grego, Peter (6 June 2012). Mars and How to Observe It. Springer Science+Business Media. p. 3. ISBN 978-1-4614-2302-7. 
  8. 8.0 8.1 8.2 Lodders, Katharina; Fegley, Bruce (1998). The Planetary Scientist's Companion. Oxford University Press. p. 190. ISBN 978-0-19-511694-6. 
  9. 9.0 9.1 Konopliv, Alex S.; Asmar, Sami W.; Folkner, William M.; Karatekin, Özgür; Nunes, Daniel C. et al. (January 2011). "Mars high resolution gravity fields from MRO, Mars seasonal gravity, and other dynamical parameters". Icarus 211 (1): 401–428. doi:10.1016/j.icarus.2010.10.004. Bibcode2011Icar..211..401K. 
  10. Hirt, C.; Claessens, S. J.; Kuhn, M.; Featherstone, W. E. (July 2012). "Kilometer-resolution gravity field of Mars: MGM2011". Planetary and Space Science 67 (1): 147–154. doi:10.1016/j.pss.2012.02.006. Bibcode2012P&SS...67..147H. 
  11. Jackson, Alan P.; Gabriel, Travis S. J.; Asphaug, Erik I. (2018-03-01). "Constraints on the pre-impact orbits of Solar system giant impactors" (in en). Monthly Notices of the Royal Astronomical Society 474 (3): 2924–2936. doi:10.1093/mnras/stx2901. ISSN 0035-8711. 
  12. Allison, Michael; Schmunk, Robert. "Mars24 Sunclock — Time on Mars". 
  13. Mallama, A. (2007). "The magnitude and albedo of Mars". Icarus 192 (2): 404–416. doi:10.1016/j.icarus.2007.07.011. Bibcode2007Icar..192..404M. 
  14. 14.0 14.1 14.2 14.3 14.4 Mallama, Anthony; Hilton, James L. (October 2018). "Computing apparent planetary magnitudes for The Astronomical Almanac". Astronomy and Computing 25: 10–24. doi:10.1016/j.ascom.2018.08.002. Bibcode2018A&C....25...10M. 
  15. 15.0 15.1 15.2 15.3 15.4 "Mars Exploration Rover Mission: Spotlight". 12 June 2007.  This article incorporates text from this source, which is in the public domain.
  16. 16.0 16.1 Sharp, Tim; Gordon, Jonathan; Tillman, Nola (2022-01-31). "What is the Temperature of Mars?" (in en). 
  17. Sample, Ian (26 June 2008). "Cataclysmic impact created north-south divide on Mars". The Guardian (London). 
  18. 18.0 18.1 "NASA – NASA Rover Finds Clues to Changes in Mars' Atmosphere". NASA.  This article incorporates text from this source, which is in the public domain.
  19. "Atmosphere". 
  20. 20.0 20.1 Byrne, Shane; Ingersoll, Andrew P. (2003). "A Sublimation Model for Martian South Polar Ice Features". Science 299 (5609): 1051–1053. doi:10.1126/science.1080148. PMID 12586939. Bibcode2003Sci...299.1051B. 
  21. 21.0 21.1 "Polar Caps". 
  22. Amos, Jonathan (2021-05-15). "China lands its Zhurong rover on Mars". BBC News. 
  23. 23.0 23.1 Rees, Martin J., ed (October 2012). Universe: The Definitive Visual Guide. New York: Dorling Kindersley. pp. 160–161. ISBN 978-0-7566-9841-6. 
  24. "The Lure of Hematite". Science@NASA. NASA. 28 March 2001. 
  25. Peplow, Mark (6 May 2004). "How Mars got its rust". Nature: news040503–6. doi:10.1038/news040503-6. Retrieved 10 March 2007. 
  26. 26.0 26.1 NASA – Mars in a Minute: Is Mars Really Red? (Transcript) This article incorporates text from this source, which is in the public domain.
  27. Nimmo, Francis; Tanaka, Ken (2005). "Early Crustal Evolution of Mars". Annual Review of Earth and Planetary Sciences 33 (1): 133–161. doi:10.1146/ Bibcode2005AREPS..33..133N. 
  28. 28.0 28.1 "In Depth | Mars". 
  29. Rivoldini, A.; Van Hoolst, T.; Verhoeven, O.; Mocquet, A.; Dehant, V. (June 2011). "Geodesy constraints on the interior structure and composition of Mars". Icarus 213 (2): 451–472. doi:10.1016/j.icarus.2011.03.024. Bibcode2011Icar..213..451R. 
  30. 30.0 30.1 Jacqué, Dave (26 September 2003). "APS X-rays reveal secrets of Mars' core". Argonne National Laboratory. 
  31. "crust" (in en). National Geographic Society. 2015-05-29. 
  32. Golombek, M.; Warner, N. H.; Grant, J. A.; Hauber, E.; Ansan, V.; Weitz, C. M. et al. (24 February 2020). "Geology of the InSight landing site on Mars". Nature Geoscience 11 (1014): 1014. doi:10.1038/s41467-020-14679-1. PMID 32094337. Bibcode2020NatCo..11.1014G. 
  33. Banerdt, W. Bruce; Smrekar, Suzanne E.; Banfield, Don; Giardini, Domenico; Golombek, Matthew; Johnson, Catherine L. et al. (2020). "Initial results from the in Sight mission on Mars". Nature Geoscience 13 (3): 183–189. doi:10.1038/s41561-020-0544-y. Bibcode2020NatGe..13..183B. 
  34. Yirka, Bob (19 March 2021). "Data from Insight reveals size of Mars's core". 
  35. 35.0 35.1 Stähler, Simon C.; Khan, Amir; Banerdt, W. Bruce; Lognonné, Philippe; Giardini, Domenico; Ceylan, Savas et al. (23 July 2021). "Seismic detection of the martian core". Science 373 (6553): 443–448. doi:10.1126/science.abi7730. PMID 34437118. Bibcode2021Sci...373..443S. 
  36. Khan, Amir; Ceylan, Savas; van Driel, Martin; Giardini, Domenico; Lognonné, Philippe; Samuel, Henri et al. (23 July 2021). "Upper mantle structure of Mars from InSight seismic data". Science 373 (6553): 434–438. doi:10.1126/science.abf2966. PMID 34437116. Bibcode2021Sci...373..434K. 
  37. Knapmeyer-Endrun, Brigitte; Panning, Mark P.; Bissig, Felix; Joshi, Rakshit; Khan, Amir; Kim, Doyeon et al. (23 July 2021). "Thickness and structure of the martian crust from InSight seismic data". Science 373 (6553): 438–443. doi:10.1126/science.abf8966. PMID 34437117. Bibcode2021Sci...373..438K. 
  38. McSween, Harry Y.; Taylor, G. Jeffrey; Wyatt, Michael B. (May 2009). "Elemental Composition of the Martian Crust". Science 324 (5928): 736–739. doi:10.1126/science.1165871. PMID 19423810. Bibcode2009Sci...324..736M. 
  39. Bandfield, Joshua L. (June 2002). "Global mineral distributions on Mars". Journal of Geophysical Research: Planets 107 (E6): 9–1–9–20. doi:10.1029/2001JE001510. Bibcode2002JGRE..107.5042B. 
  40. Christensen, Philip R. (27 June 2003). "Morphology and Composition of the Surface of Mars: Mars Odyssey THEMIS Results". Science 300 (5628): 2056–2061. doi:10.1126/science.1080885. PMID 12791998. Bibcode2003Sci...300.2056C. 
  41. Tanaka, Kenneth L.; Skinner, James A. Jr.; Dohm, James M.; Irwin, Rossman P. III; Kolb, Eric J.; Fortezzo, Corey M.; Platz, Thomas; Michael, Gregory G. et al. (14 July 2014). "Geologic Map of Mars – 2014". USGS.  This article incorporates text from this source, which is in the public domain.
  42. "Magnetic Fields and Mars". Mars Global Surveyor @ NASA. 9 November 2006.  This article incorporates text from this source, which is in the public domain.
  43. Neal-Jones, Nancy; O'Carroll, Cynthia. "New Map Provides More Evidence Mars Once Like Earth". NASA/Goddard Space Flight Center.  This article incorporates text from this source, which is in the public domain.
  44. Halliday, A. N.; Wänke, H.; Birck, J.-L.; Clayton, R. N. (2001). "The Accretion, Composition and Early Differentiation of Mars". Space Science Reviews 96 (1/4): 197–230. doi:10.1023/A:1011997206080. Bibcode2001SSRv...96..197H. 
  45. Zharkov, V. N. (1993). "The role of Jupiter in the formation of planets". Evolution of the Earth and Planets. Washington DC American Geophysical Union Geophysical Monograph Series. 74. pp. 7–17. doi:10.1029/GM074p0007. ISBN 978-1-118-66669-2. Bibcode1993GMS....74....7Z. 
  46. Lunine, Jonathan I.; Chambers, John; Morbidelli, Alessandro; Leshin, Laurie A. (2003). "The origin of water on Mars". Icarus 165 (1): 1–8. doi:10.1016/S0019-1035(03)00172-6. Bibcode2003Icar..165....1L. 
  47. Barlow, Nadine G. (5–7 October 1988). "Conditions on Early Mars: Constraints from the Cratering Record". in H. Frey. Easton, Maryland: Lunar and Planetary Institute. p. 15. 
  48. Yeager, Ashley (19 July 2008). "Impact May Have Transformed Mars". 
  49. Minkel, J. R. (2008-06-26). "Giant Asteroid Flattened Half of Mars, Studies Suggest". Scientific American. 
  50. Chang, Kenneth (26 June 2008). "Huge Meteor Strike Explains Mars's Shape, Reports Say". The New York Times. 
  51. Tanaka, K. L. (1986). "The Stratigraphy of Mars". Journal of Geophysical Research 91 (B13): E139–E158. doi:10.1029/JB091iB13p0E139. Bibcode1986JGR....91E.139T. 
  52. Hartmann, William K.; Neukum, Gerhard (2001). "Cratering Chronology and the Evolution of Mars". Space Science Reviews 96 (1/4): 165–194. doi:10.1023/A:1011945222010. Bibcode2001SSRv...96..165H. 
  53. 53.0 53.1 53.2 "ESA Science & Technology - The Ages of Mars". 
  54. Mitchell, Karl L.; Wilson, Lionel (2003). "Mars: recent geological activity : Mars: a geologically active planet". Astronomy & Geophysics 44 (4): 4.16–4.20. doi:10.1046/j.1468-4004.2003.44416.x. Bibcode2003A&G....44d..16M. 
  55. Russell, Patrick (2008-03-03). "Caught in Action: Avalanches on North Polar Scarps". 
  56. "HiRISE Catches an Avalanche on Mars" (in en-US). 2020-08-12. 
  57. "Martian soil 'could support life'". BBC News. 27 June 2008. 
  58. Kounaves, S. P. (2010). "Wet Chemistry Experiments on the 2007 Phoenix Mars Scout Lander: Data Analysis and Results". J. Geophys. Res. 115 (E3): E00–E10. doi:10.1029/2008JE003084. Bibcode2009JGRE..114.0A19K. 
  59. Kounaves, S. P. (2010). "Soluble Sulfate in the Martian Soil at the Phoenix Landing Site". Geophysical Research Letters 37 (9): L09201. doi:10.1029/2010GL042613. Bibcode2010GeoRL..37.9201K. 
  60. David, Leonard (13 June 2013). "Toxic Mars: Astronauts Must Deal with Perchlorate on the Red Planet". 
  61. Sample, Ian (6 July 2017). "Mars covered in toxic chemicals that can wipe out living organisms, tests reveal". The Guardian. 
  62. Verba, Circe (2 July 2009). "Dust Devil Etch-A-Sketch (ESP_013751_1115)". University of Arizona. 
  63. Schorghofer, Norbert; Aharonson, Oded; Khatiwala, Samar (2002). "Slope streaks on Mars: Correlations with surface properties and the potential role of water". Geophysical Research Letters 29 (23): 41–1. doi:10.1029/2002GL015889. Bibcode2002GeoRL..29.2126S. 
  64. Gánti, Tibor (2003). "Dark Dune Spots: Possible Biomarkers on Mars?". Origins of Life and Evolution of the Biosphere 33 (4): 515–557. doi:10.1023/A:1025705828948. PMID 14604189. Bibcode2003OLEB...33..515G. 
  65. Heldmann, Jennifer L. (7 May 2005). "Formation of Martian gullies by the action of liquid water flowing under current Martian environmental conditions". Journal of Geophysical Research 110 (E5): Eo5004. doi:10.1029/2004JE002261. Bibcode2005JGRE..11005004H. Retrieved 17 September 2008.  '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 vapor pressure of water and surface temperatures in equatorial regions can reach 273 K for parts of the day [Haberle et al., 2001]'
  66. "Mars' South Pole Ice Deep and Wide". NASA. 15 March 2007.  This article incorporates text from this source, which is in the public domain.
  67. "Water ice in crater at Martian north pole". ESA. 28 July 2005. 
  68. Whitehouse, David (24 January 2004). "Long history of water and Mars". BBC News. 
  69. Holt, John W.; Safaeinili, Ali; Plaut, Jeffrey J. et al. (2008-11-21). "Radar Sounding Evidence for Buried Glaciers in the Southern Mid-Latitudes of Mars" (in en). Science 322 (5905): 1235–1238. doi:10.1126/science.1164246. ISSN 0036-8075. PMID 19023078. 
  70. "NASA Spacecraft Confirms Martian Water, Mission Extended". Science @ NASA. 31 July 2008.  This article incorporates text from this source, which is in the public domain.
  71. Kerr, Richard A. (4 March 2005). "Ice or Lava Sea on Mars? A Transatlantic Debate Erupts". Science 307 (5714): 1390–1391. doi:10.1126/science.307.5714.1390a. PMID 15746395. 
  72. Jaeger, W. L. (21 September 2007). "Athabasca Valles, Mars: A Lava-Draped Channel System". Science 317 (5845): 1709–1711. doi:10.1126/science.1143315. PMID 17885126. Bibcode2007Sci...317.1709J. 
  73. "Valles Marineris; The Grand Canyon of Mars". USGS. 26 August 2003.  This article incorporates text from this source, which is in the public domain.
  74. Murray, John B. (17 March 2005). "Evidence from the Mars Express High Resolution Stereo Camera for a frozen sea close to Mars' equator". Nature 434 (703): 352–356. doi:10.1038/nature03379. PMID 15772653. Bibcode2005Natur.434..352M. 
  75. Craddock, R.A.; Howard, A.D. (2002). "The case for rainfall on a warm, wet early Mars". Journal of Geophysical Research 107 (E11): 21–1. doi:10.1029/2001JE001505. Bibcode2002JGRE..107.5111C. 
  76. Malin, Michael C.; Edgett, KS (30 June 2000). "Evidence for Recent Groundwater Seepage and Surface Runoff on Mars". Science 288 (5475): 2330–2335. doi:10.1126/science.288.5475.2330. PMID 10875910. Bibcode2000Sci...288.2330M. 
  77. 77.0 77.1 "NASA Images Suggest Water Still Flows in Brief Spurts on Mars". NASA. 6 December 2006.  This article incorporates text from this source, which is in the public domain.
  78. "Water flowed recently on Mars". BBC. 6 December 2006. 
  79. "Water May Still Flow on Mars, NASA Photo Suggests". NASA. 6 December 2006.  This article incorporates text from this source, which is in the public domain.
  80. Lewis, K.W.; Aharonson, O. (2006). "Stratigraphic analysis of the distributary fan in Eberswalde crater using stereo imagery". Journal of Geophysical Research 111 (E06001): E06001. doi:10.1029/2005JE002558. Bibcode2006JGRE..111.6001L. 
  81. Matsubara, Y.; Howard, A.D.; Drummond, S.A. (2011). "Hydrology of early Mars: Lake basins". Journal of Geophysical Research 116 (E04001): E04001. doi:10.1029/2010JE003739. Bibcode2011JGRE..116.4001M. 
  82. Steep Slopes on Mars Reveal Structure of Buried Ice. NASA Press Release. January 11, 2018. This article incorporates text from this source, which is in the public domain.
  83. Dundas, Colin M.; Bramson, Ali M.; Ojha, Lujendra; Wray, James J.; Mellon, Michael T.; Byrne, Shane; McEwen, Alfred S.; Putzig, Nathaniel E. et al. (2018). "Exposed subsurface ice sheets in the Martian mid-latitudes". Science 359 (6372): 199–201. doi:10.1126/science.aao1619. PMID 29326269. Bibcode2018Sci...359..199D. 
  84. "Mineral in Mars 'Berries' Adds to Water Story" (Press release). NASA. 3 March 2004. Archived from the original on 9 November 2007. Retrieved 13 June 2006. This article incorporates text from this source, which is in the public domain.
  85. "Mars Exploration Rover Mission: Science". NASA. 12 July 2007.  This article incorporates text from this source, which is in the public domain.
  86. Elwood Madden, M. E.; Bodnar, R. J.; Rimstidt, J. D. (October 2004). "Jarosite as an indicator of water-limited chemical weathering on Mars" (in en). Nature 431 (7010): 821–823. doi:10.1038/nature02971. ISSN 0028-0836. PMID 15483605. 
  87. "Mars Rover Investigates Signs of Steamy Martian Past" (in en-US). 2007-12-10. 
  88. "NASA – NASA Mars Rover Finds Mineral Vein Deposited by Water". NASA. 7 December 2011.  This article incorporates text from this source, which is in the public domain.
  89. Lovett, Richard A. (8 December 2011). "Rover Finds "Bulletproof" Evidence of Water on Early Mars". National Geographic. 
  90. Lovett, Richard A. (26 June 2012). "Mars Has "Oceans" of Water Inside?". National Geographic. 
  91. McCubbin, Francis M.; Hauri, Erik H.; Elardo, Stephen M.; Vander Kaaden, Kathleen E.; Wang, Jianhua; Shearer, Charles K. (August 2012). "Hydrous melting of the martian mantle produced both depleted and enriched shergottites" (in en). Geology 40 (8): 683–686. doi:10.1130/G33242.1. ISSN 1943-2682. Bibcode2012Geo....40..683M. 
  92. 92.0 92.1 Webster, Guy; Brown, Dwayne (18 March 2013). "Curiosity Mars Rover Sees Trend in Water Presence". NASA.  This article incorporates text from this source, which is in the public domain.
  93. Rincon, Paul (19 March 2013). "Curiosity breaks rock to reveal dazzling white interior". BBC News (BBC). 
  94. "NASA Confirms Evidence That Liquid Water Flows on Today's Mars". NASA. 28 September 2015.  This article incorporates text from this source, which is in the public domain.
  95. Drake, Nadia (28 September 2015). "NASA Finds 'Definitive' Liquid Water on Mars". 
  96. Ojha, L.; Wilhelm, M. B.; Murchie, S. L.; McEwen, A. S.; Wray, J. J.; Hanley, J.; Massé, M.; Chojnacki, M. (2015). "Spectral evidence for hydrated salts in recurring slope lineae on Mars". Nature Geoscience 8 (11): 829–832. doi:10.1038/ngeo2546. Bibcode2015NatGe...8..829O. 
  97. Moskowitz, Clara. "Water Flows on Mars Today, NASA Announces". 
  98. McEwen, Alfred; Lujendra, Ojha; Dundas, Colin; Mattson, Sarah; Bryne, S; Wray, J; Cull, Selby; Murchie, Scott et al. (5 August 2011). "Seasonal Flows on Warm Martian Slopes". Science 333 (6043): 740–743. doi:10.1126/science.1204816. PMID 21817049. Bibcode2011Sci...333..740M. Retrieved 28 September 2015. 
  99. Dundas, Colin M.; McEwen, Alfred S.; Chojnacki, Matthew; Milazzo, Moses P.; Byrne, Shane; McElwaine, Jim N.; Urso, Anna (December 2017). "Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water" (in en). Nature Geoscience 10 (12): 903–907. doi:10.1038/s41561-017-0012-5. ISSN 1752-0908. Bibcode2017NatGe..10..903D. 
  100. Schorghofer, Norbert (2020-02-12). "Mars: Quantitative Evaluation of Crocus Melting behind Boulders". The Astrophysical Journal 890 (1): 49. doi:10.3847/1538-4357/ab612f. ISSN 1538-4357. Bibcode2020ApJ...890...49S. 
  101. Wray, James J. (2021-05-30). "Contemporary Liquid Water on Mars?" (in en). Annual Review of Earth and Planetary Sciences 49 (1): 141–171. doi:10.1146/annurev-earth-072420-071823. ISSN 0084-6597. Bibcode2021AREPS..49..141W. 
  102. Head, J.W. (1999). "Possible Ancient Oceans on Mars: Evidence from Mars Orbiter Laser Altimeter Data". Science 286 (5447): 2134–7. doi:10.1126/science.286.5447.2134. PMID 10591640. Bibcode1999Sci...286.2134H. 
  103. Kaufman, Marc (5 March 2015). "Mars Had an Ocean, Scientists Say, Pointing to New Data". The New York Times. 
  104. Sample, Ian (21 December 2018). "Mars Express beams back images of ice-filled Korolev crater". The Guardian. 
  105. "Mars Ice Deposit Holds as Much Water as Lake Superior". NASA. 22 November 2016.  This article incorporates text from this source, which is in the public domain.
  106. Staff (22 November 2016). "Scalloped Terrain Led to Finding of Buried Ice on Mars". NASA.  This article incorporates text from this source, which is in the public domain.
  107. Mitrofanov, I.; Malakhov, A.; Djachkova, M.; Golovin, D.; Litvak, M.; Mokrousov, M.; Sanin, A.; Svedhem, H. et al. (March 2022). "The evidence for unusually high hydrogen abundances in the central part of Valles Marineris on Mars" (in en). Icarus 374: 114805. doi:10.1016/j.icarus.2021.114805. Bibcode2022Icar..37414805M. 
  108. Mellon, J. T.; Feldman, W. C.; Prettyman, T. H. (2003). "The presence and stability of ground ice in the southern hemisphere of Mars". Icarus 169 (2): 324–340. doi:10.1016/j.icarus.2003.10.022. Bibcode2004Icar..169..324M. 
  109. "Mars Rovers Spot Water-Clue Mineral, Frost, Clouds". NASA. 13 December 2004.  This article incorporates text from this source, which is in the public domain.
  110. Malin, M.C.; Caplinger, M.A.; Davis, S.D. (2001). "Observational evidence for an active surface reservoir of solid carbon dioxide on Mars". Science 294 (5549): 2146–2148. doi:10.1126/science.1066416. PMID 11768358. Bibcode2001Sci...294.2146M. 
  111. "NASA - Northern Ice Cap of Mars" (in en). 
  112. Carr, Michael H. (2003). "Oceans on Mars: An assessment of the observational evidence and possible fate". Journal of Geophysical Research 108 (5042): 24. doi:10.1029/2002JE001963. Bibcode2003JGRE..108.5042C. 
  113. Phillips, Tony (7 August 2003). "Mars is Melting".  This article incorporates text from this source, which is in the public domain.
  114. Plaut, J. J (2007). "Subsurface Radar Sounding of the South Polar Layered Deposits of Mars". Science 316 (5821): 92–95. doi:10.1126/science.1139672. PMID 17363628. Bibcode2007Sci...316...92P. 
  115. Smith, Isaac B.; Holt, J. W. (2010). "Onset and migration of spiral troughs on Mars revealed by orbital radar". Nature 465 (4): 450–453. doi:10.1038/nature09049. PMID 20505722. Bibcode2010Natur.465..450S. 
  116. Hsu, Jeremy (26 May 2010). "Mystery Spirals on Mars Finally Explained". 
  117. Stiles, Lori (2009-03-25). "HiRISE Sees Signs of an Unearthly Spring". 
  118. "July 4, 2016 First Day of Spring on Mars & Juno Arrival at Jupiter". 
  119. "What Mars Maps Got Right (and Wrong) Through Time" (in en). 2016-10-19. 
  120. "Planetary Names: Categories for Naming Features on Planets and Satellites". USGS Astrogeology Science Center. 
  121. "Viking and the Resources of Mars". Humans to Mars: Fifty Years of Mission Planning, 1950–2000.  This article incorporates text from this source, which is in the public domain.
  122. Tanaka, Kenneth L.; Coles, Kenneth S.; Christensen, Philip R., eds. (2019), "Syrtis Major (MC-13)", The Atlas of Mars: Mapping its Geography and Geology (Cambridge: Cambridge University Press): pp. 136–139, doi:10.1017/9781139567428.018, ISBN 978-1-139-56742-8,, retrieved 2022-01-18 
  123. "Polar Caps". 
  124. Davies, Merton E.; Berg, Richard A. (1971-01-10). "A preliminary control net of Mars" (in en). Journal of Geophysical Research 76 (2): 373–393. doi:10.1029/JB076i002p00373. Bibcode1971JGR....76..373D. 
  125. Archinal, B. A.; Caplinger, M. (Fall 2002). "Mars, the Meridian, and Mert: The Quest for Martian Longitude". American Geophysical Union, Fall Meeting 2002 22: P22D–06. Bibcode2002AGUFM.P22D..06A. 
  126. de Vaucouleurs, Gerard; Davies, Merton E.; Sturms, Francis M., Jr. (1973), "Mariner 9 Areographic Coordinate System", Journal of Geophysical Research 78 (20): 4395–4404, doi:10.1029/JB078i020p04395, Bibcode1973JGR....78.4395D 
  127. NASA (19 April 2007). "Mars Global Surveyor: MOLA MEGDRs". 
  128. Ardalan, A. A.; Karimi, R.; Grafarend, E. W. (2009). "A New Reference Equipotential Surface, and Reference Ellipsoid for the Planet Mars". Earth, Moon, and Planets 106 (1): 1–13. doi:10.1007/s11038-009-9342-7. ISSN 0167-9295. 
  129. Zeitler, W.; Ohlhof, T.; Ebner, H. (2000). "Recomputation of the global Mars control-point network". Photogrammetric Engineering & Remote Sensing 66 (2): 155–161. Retrieved 2022-02-15. 
  130. Lunine, Cynthia J. (1999). Earth: evolution of a habitable world. Cambridge University Press. p. 183. ISBN 978-0-521-64423-5. 
  131. "ESA Science & Technology - Using iMars: Viewing Mars Express data of the MC11 quadrangle". 
  132. Webster, Guy; Brown, Dwayne (May 22, 2014). "NASA Mars Weathercam Helps Find Big New Crater". NASA.  This article incorporates text from this source, which is in the public domain.
  133. Andrews-Hanna, Jeffrey C.; Zuber, Maria T.; Banerdt, W. Bruce (2008). "The Borealis basin and the origin of the Martian crustal dichotomy". Nature 453 (7199): 1212–1215. doi:10.1038/nature07011. PMID 18580944. Bibcode2008Natur.453.1212A. 
  134. 134.0 134.1 Choi, Charles (2021-10-01). "Mars: What We Know About the Red Planet" (in en). 
  135. Moskowitz, Clara (2008-06-25). "Huge Impact Created Mars' Split Personality" (in en). 
  136. Wright, Shawn (4 April 2003). "Infrared Analyses of Small Impact Craters on Earth and Mars". University of Pittsburgh. 
  137. Vogt, Gregory L. (2008) (in en). Landscapes of Mars. New York, NY: Springer. pp. 44. doi:10.1007/978-0-387-75468-0. ISBN 978-0-387-75467-3. 
  138. "ESA Science & Technology - Craters within the Hellas Basin". 
  139. Rodrigue, Christine M.. "The Geography of Mars". 
  140. "41st Lunar and Planetary Science Conference (2010)". 
  141. Wetherill, G. W. (1999). "Problems Associated with Estimating the Relative Impact Rates on Mars and the Moon". Earth, Moon, and Planets 9 (1–2): 227–231. doi:10.1007/BF00565406. Bibcode1974Moon....9..227W. 
  142. Costard, Francois M. (1989). "The spatial distribution of volatiles in the Martian hydrolithosphere". Earth, Moon, and Planets 45 (3): 265–290. doi:10.1007/BF00057747. Bibcode1989EM&P...45..265C. 
  143. "Mars Atlas: Olympus Mons". 
  144. 144.0 144.1 Plescia, J. B. (2004). "Morphometric Properties of Martian Volcanoes". J. Geophys. Res. 109 (E3): E03003. doi:10.1029/2002JE002031. Bibcode2004JGRE..109.3003P. 
  145. Comins, Neil F. (2012). Discovering the Essential Universe. W. H. Freeman. p. 148. ISBN 978-1-4292-5519-6. 
  146. Schenk, P. (2012). "The Geologically Recent Giant Impact Basins at Vesta's South Pole". Science 336 (6082): 694–697. doi:10.1126/science.1223272. PMID 22582256. Bibcode2012Sci...336..694S. 
  147. Sagan, Carl; Fox, Paul (August 1975). "The canals of Mars: An assessment after Mariner 9" (in en). Icarus 25 (4): 602–612. doi:10.1016/0019-1035(75)90042-1. Bibcode1975Icar...25..602S. 
  148. Wolpert, Stuart (9 August 2012). "UCLA scientist discovers plate tectonics on Mars". UCLA. 
  149. Lin, An (4 June 2012). "Structural analysis of the Valles Marineris fault zone: Possible evidence for large-scale strike-slip faulting on Mars". Lithosphere 4 (4): 286–330. doi:10.1130/L192.1. Bibcode2012Lsphe...4..286Y. 
  150. "Themis Observes Possible Cave Skylights on Mars". Lunar and Planetary Science XXXVIII. 2007. 
  151. "NAU researchers find possible caves on Mars". Inside NAU (Northern Arizona University) 4 (12). 28 March 2007. 
  152. Rincon, Paul (17 March 2007). "'Cave entrances' spotted on Mars". BBC News. 
  153. "The Caves of Mars | U.S. Geological Survey". USGS. 
  154. Jones, Nancy; Steigerwald, Bill; Brown, Dwayne; Webster, Guy (October 14, 2014). "NASA Mission Provides Its First Look at Martian Upper Atmosphere". NASA.  This article incorporates text from this source, which is in the public domain.
  155. 155.0 155.1 Philips, Tony (31 January 2001). "The Solar Wind at Mars".  This article incorporates text from this source, which is in the public domain.
  156. Grossman, Lisa (20 January 2011). "Multiple Asteroid Strikes May Have Killed Mars's Magnetic Field". Wired. Retrieved 2022-03-30. 
  157. 157.0 157.1 Jakosky, Bruce M. (2022-04-01). "How did Mars lose its atmosphere and water?" (in en). Physics Today 75 (4): 62–63. doi:10.1063/PT.3.4988. ISSN 0031-9228. Bibcode2022PhT....75d..62J. 
  158. Lundin, R (2004). "Solar Wind-Induced Atmospheric Erosion at Mars: First Results from ASPERA-3 on Mars Express". Science 305 (5692): 1933–1936. doi:10.1126/science.1101860. PMID 15448263. Bibcode2004Sci...305.1933L. 
  159. Bolonkin, Alexander A. (2009). Artificial Environments on Mars. Berlin Heidelberg: Springer. pp. 599–625. ISBN 978-3-642-03629-3. 
  160. Atkinson, Nancy (17 July 2007). "The Mars Landing Approach: Getting Large Payloads to the Surface of the Red Planet". 
  161. Carr, Michael H. (2006). The surface of Mars. 6. Cambridge University Press. p. 16. ISBN 978-0-521-87201-0. 
  162. "Mars Facts | All About Mars" (in en). 
  163. Mahaffy, P. R. (19 July 2013). "Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover". Science 341 (6143): 263–266. doi:10.1126/science.1237966. PMID 23869014. Bibcode2013Sci...341..263M. 
  164. Lemmon, M. T. (2004). "Atmospheric Imaging Results from Mars Rovers". Science 306 (5702): 1753–1756. doi:10.1126/science.1104474. PMID 15576613. Bibcode2004Sci...306.1753L. 
  165. Sample, Ian (7 June 2018). "Nasa Mars rover finds organic matter in ancient lake bed". The Guardian. 
  166. Mumma, Michael J. (20 February 2009). "Strong Release of Methane on Mars in Northern Summer 2003". Science 323 (5917): 1041–1045. doi:10.1126/science.1165243. PMID 19150811. Bibcode2009Sci...323.1041M. 
  167. Franck, Lefèvre; Forget, François (6 August 2009). "Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics". Nature 460 (7256): 720–723. doi:10.1038/nature08228. PMID 19661912. Bibcode2009Natur.460..720L. 
  168. 168.0 168.1 Oze, C.; Sharma, M. (2005). "Have olivine, will gas: Serpentinization and the abiogenic production of methane on Mars". Geophysical Research Letters 32 (10): L10203. doi:10.1029/2005GL022691. Bibcode2005GeoRL..3210203O. 
  169. Webster, Christopher R.; Mahaffy, Paul R.; Pla-Garcia, Jorge; Rafkin, Scot C. R.; Moores, John E.; Atreya, Sushil K. et al. (June 2021). "Day-night differences in Mars methane suggest nighttime containment at Gale crater". Astronomy & Astrophysics 650: A166. doi:10.1051/0004-6361/202040030. ISSN 0004-6361. Bibcode2021A&A...650A.166W. 
  170. Wright, Katherine (2022-03-22). "Sound Speed Measured on Mars" (in en). Physics 15: 43. doi:10.1103/Physics.15.43. Bibcode2022PhyOJ..15...43W. 
  171. Maurice, S.; Chide, B.; Murdoch, N.; Lorenz, R. D.; Mimoun, D.; Wiens, R. C.; Stott, A.; Jacob, X. et al. (2022-04-01). "In situ recording of Mars soundscape" (in en). Nature. doi:10.1038/s41586-022-04679-0. ISSN 0028-0836. PMID 35364602. 
  172. Chow, Denise (2021-12-07). "In an ultraviolet glow, auroras on Mars spotted by UAE orbiter" (in en). 
  173. "Auroras on Mars – NASA Science".  This article incorporates text from this source, which is in the public domain.
  174. Brown, Dwayne; Neal-Jones, Nancy; Steigerwald, Bill; Scott, Jim (18 March 2015). "NASA Spacecraft Detects Aurora and Mysterious Dust Cloud around Mars". NASA.  This article incorporates text from this source, which is in the public domain.
  175. Deighan, J.; Jain, S. K.; Chaffin, M. S.; Fang, X.; Halekas, J. S.; Clarke, J. T.; Schneider, N. M.; Stewart, A. I. F. et al. (October 2018). "Discovery of a proton aurora at Mars" (in en). Nature Astronomy 2 (10): 802–807. doi:10.1038/s41550-018-0538-5. ISSN 2397-3366. Bibcode2018NatAs...2..802D. 
  176. 176.0 176.1 Schneider, N. M.; Jain, S. K.; Deighan, J.; Nasr, C. R.; Brain, D. A.; Larson, D.; Lillis, R.; Rahmati, Ali et al. (2018-08-16). "Global Aurora on Mars During the September 2017 Space Weather Event" (in en). Geophysical Research Letters 45 (15): 7391–7398. doi:10.1029/2018GL077772. Bibcode2018GeoRL..45.7391S. 
  177. Webster, Guy; Neal-Jones, Nancy; Scott, Jim; Schmid, Deb; Cantillo, Laurie; Brown, Dwayne (29 September 2017). "Large Solar Storm Sparks Global Aurora and Doubles Radiation Levels on the Martian Surface". NASA.  This article incorporates text from this source, which is in the public domain.
  178. "Mars' desert surface...". MGCM Press release. NASA.  This article incorporates text from this source, which is in the public domain.
  179. Kluger, Jeffrey (1 September 1992). "Mars, in Earth's Image". Discover Magazine 13 (9): 70. Bibcode1992Disc...13...70K. Retrieved 3 November 2009. 
  180. Hille, Karl (2015-09-18). "The Fact and Fiction of Martian Dust Storms". 
  181. Goodman, Jason C. (22 September 1997). "The Past, Present, and Possible Future of Martian Climate". MIT. 
  182. Philips, Tony (16 July 2001). "Planet Gobbling Dust Storms". Science @ NASA.  This article incorporates text from this source, which is in the public domain.
  183. Greicius, Tony (2018-06-08). "Opportunity Hunkers Down During Dust Storm". 
  184. Badescu, Viorel (2009). Mars: Prospective Energy and Material Resources (illustrated ed.). Springer Science & Business Media. p. 600. ISBN 978-3-642-03629-3. 
  185. Barlow, Nadine G. (2008). Mars: an introduction to its interior, surface and atmosphere. Cambridge planetary science. 8. Cambridge University Press. p. 21. ISBN 978-0-521-85226-5. 
  186. Vitagliano, Aldo (2003). "Mars' Orbital eccentricity over time". Solex. Universita' degli Studi di Napoli Federico II. 
  187. 187.0 187.1 187.2 Meeus, Jean (March 2003). "When Was Mars Last This Close?". International Planetarium Society. 
  188. Wright, W. H. (1947). Biographical Memoir of William Wallace Campbell, 1862–1938. Washington, D.C.. Retrieved 2021-05-22. 
  189. Salisbury, F. B. (1962). "Martian Biology". Science 136 (3510): 17–26. doi:10.1126/science.136.3510.17. PMID 17779780. Bibcode1962Sci...136...17S. 
  190. Kopparapu, Ravi Kumar; Ramirez, Ramses; Kasting, James F. et al. (2013). "Habitable Zones Around Main-Sequence Stars: New Estimates". The Astrophysical Journal 765 (2): 131. doi:10.1088/0004-637X/765/2/131. Bibcode2013ApJ...765..131K. 
  191. Briggs, Helen (15 February 2008). "Early Mars 'too salty' for life". BBC News. 
  192. Hannsson, Anders (1997). Mars and the Development of Life. Wiley. ISBN 978-0-471-96606-7. 
  193. Chang, Kenneth (August 4, 2021). "Gilbert V. Levin, Who Said He Found Signs of Life on Mars, Dies at 97". The New York Times. Retrieved August 4, 2021. 
  194. "Phoenix Returns Treasure Trove for Science". NASA/JPL. 6 June 2008.  This article incorporates text from this source, which is in the public domain.
  195. Bluck, John (5 July 2005). "NASA Field-Tests the First System Designed to Drill for Subsurface Martian Life". NASA.  This article incorporates text from this source, which is in the public domain.
  196. Kounaves, S. P. (2014). "Evidence of martian perchlorate, chlorate, and nitrate in Mars meteorite EETA79001: implications for oxidants and organics". Icarus 229: 206–213. doi:10.1016/j.icarus.2013.11.012. Bibcode2014Icar..229..206K. 
  197. Golden, D. C. (2004). "Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001". American Mineralogist 89 (5–6): 681–695. doi:10.2138/am-2004-5-602. Bibcode2004AmMin..89..681G. Retrieved 25 December 2010. 
  198. Krasnopolsky, Vladimir A.; Maillard, Jean-Pierre; Owen, Tobias C. (2004). "Detection of methane in the Martian atmosphere: evidence for life?". Icarus 172 (2): 537–547. doi:10.1016/j.icarus.2004.07.004. Bibcode2004Icar..172..537K. 
  199. Peplow, Mark (25 February 2005). "Formaldehyde claim inflames Martian debate". Nature. doi:10.1038/news050221-15. 
  200. Nickel, Mark (18 April 2014). "Impact glass stores biodata for millions of years". Brown University. 
  201. Schultz, P. H.; Harris, R. Scott; Clemett, S. J.; Thomas-Keprta, K. L.; Zárate, M. (June 2014). "Preserved flora and organics in impact melt breccias". Geology 42 (6): 515–518. doi:10.1130/G35343.1. Bibcode2014Geo....42..515S. 
  202. Brown, Dwayne; Webster, Guy; Stacey, Kevin (8 June 2015). "NASA Spacecraft Detects Impact Glass on Surface of Mars" (Press release). NASA. Retrieved 9 June 2015. This article incorporates text from this source, which is in the public domain.
  203. Stacey, Kevin (8 June 2015). "Martian glass: Window into possible past life?". Brown University. 
  204. Temming, Maria (12 June 2015). "Exotic Glass Could Help Unravel Mysteries of Mars". Scientific American. 
  205. "Close Inspection for Phobos". ESA website. 
  206. "Planetary Names". 
  207. Hunt, G. E.; Michael, W. H.; Pascu, D.; Veverka, J.; Wilkins, G. A.; Woolfson, M. (1978). "The Martian satellites—100 years on". Quarterly Journal of the Royal Astronomical Society 19: 90–109. Bibcode1978QJRAS..19...90H. 
  208. "Phobos". 2019-12-19. 
  209. "Explaining the Birth of the Martian Moons" (in en-US). American Astronomical Society. 23 September 2016. 
  210. Andert, T. P.; Rosenblatt, P.; Pätzold, M.; Häusler, B.; Dehant, V.; Tyler, G. L.; Marty, J. C. (7 May 2010). "Precise mass determination and the nature of Phobos". Geophysical Research Letters 37 (L09202): L09202. doi:10.1029/2009GL041829. Bibcode2010GeoRL..37.9202A. 
  211. 211.0 211.1 Giuranna, M.; Roush, T. L.; Duxbury, T.; Hogan, R. C.; Geminale, A.; Formisano, V. (2010). "Compositional Interpretation of PFS/MEx and TES/MGS Thermal Infrared Spectra of Phobos". Retrieved 1 October 2010. 
  212. Bagheri, Amirhossein; Khan, Amir; Efroimsky, Michael; Kruglyakov, Mikhail; Giardini, Domenico (2021-02-22). "Dynamical evidence for Phobos and Deimos as remnants of a disrupted common progenitor". Nature Astronomy 5 (6): 539–543. doi:10.1038/s41550-021-01306-2. Bibcode2021NatAs...5..539B. 
  213. Adler, M.; Owen, W.; Riedel, J. (June 2012). "Use of MRO Optical Navigation Camera to Prepare for Mars Sample Return". Concepts and Approaches for Mars Exploration. 12–14 June 2012. Houston, Texas.. 4337. Bibcode2012LPICo1679.4337A. 
  214. Drake, Nadia (2020-07-29). "Why we explore Mars—and what decades of missions have revealed" (in en). 
  215. "In Depth | Mariner 04". "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 space."  This article incorporates text from this source, which is in the public domain.; "NASA – NSSDCA – Spacecraft – Details". "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."  This article incorporates text from this source, which is in the public domain.
  216. Ward, Peter Douglas; Brownlee, Donald (2000). Rare earth: why complex life is uncommon in the universe (2nd ed.). Springer. p. 253. ISBN 978-0-387-95289-5. 
  217. Bond, Peter (2007). Distant worlds: milestones in planetary exploration. Springer. p. 119. ISBN 978-0-387-40212-3. 
  218. "New Online Tools Bring NASA's Journey to Mars to a New Generation". 5 August 2015. 
  219. Culpan, Daniel (10 July 2015). "Explore the Red Planet with Nasa's Mars Trek". Wired UK. Retrieved 31 March 2022. 
  220. Strickland, Ashley (2021-02-12). "Meet the orbiters that help rovers on Mars talk to Earth". 
  221. Hill, Tanya. "As new probes reach Mars, here's what we know so far from trips to the red planet" (in en). 
  222. "Quick Facts | Mission" (in en). 
  223. Myers, Steven Lee; Chang, Kenneth (14 May 2021). "China's Mars Rover Mission Lands on the Red Planet". The New York Times. 
  224. "Second ExoMars mission moves to next launch opportunity in 2020" (in en). 2 May 2016. 
  225. "ExoMars to take off for the Red Planet in 2022" (in en). 12 March 2020. 
  226. Amos, Jonathan (2022-03-17). "Joint Europe-Russia Mars rover project is parked" (in en-GB). BBC News. 
  227. "NASA, ESA Officials Outline Latest Mars Sample Return Plans". August 13, 2019. 
  228. "Mars Sample Return Campaign" (in en). 
  229. "S.442 - National Aeronautics and Space Administration Transition Authorization Act of 2017". 2017-03-21. 
  230. Foust, Jeff (2019-04-18). "Independent report concludes 2033 human Mars mission is not feasible". 
  231. "China plans its first crewed mission to Mars in 2033". Reuters. 23 June 2021. Retrieved 20 December 2021. 
  232. "Deimos". Planetary Societies's Explore the Cosmos. 
  233. Bertaux, Jean-Loup (2005). "Discovery of an aurora on Mars". Nature 435 (7043): 790–794. doi:10.1038/nature03603. PMID 15944698. Bibcode2005Natur.435..790B. 
  234. Bell, J. F., III (7 July 2005). "Solar eclipses of Phobos and Deimos observed from the surface of Mars". Nature 436 (7047): 55–57. doi:10.1038/nature03437. PMID 16001060. Bibcode2005Natur.436...55B. 
  235. Lorenz, Ralph D.; Lemmon, Mark T.; Mueller, Nils T. (2020-04-28). "A Transit Lightcurve of Deimos, Observed with the InSight Solar Arrays". Research Notes of the AAS 4 (4): 57. doi:10.3847/2515-5172/ab8d21. ISSN 2515-5172. Bibcode2020RNAAS...4...57L. 
  236. Meeus, J.; Goffin, E. (1983). "Transits of Earth as seen from Mars". Journal of the British Astronomical Association 93 (3): 120–123. Bibcode1983JBAA...93..120M. 
  237. St. Fleur, Nicholas (9 January 2017). "Looking at Your Home Planet from Mars". The New York Times. 
  238. Mallama, A. (2011). "Planetary magnitudes". Sky and Telescope 121 (1): 51–56. 
  239. "Mars Close Approach | Mars in our Night Sky" (in en). 
  240. Zeilik, Michael (2002). Astronomy: the Evolving Universe (9th ed.). Cambridge University Press. p. 14. ISBN 978-0-521-80090-7. 
  241. Jacques Laskar (14 August 2003). "Primer on Mars oppositions". IMCCE, Paris Observatory.  (Solex results)
  242. "Close encounter: Mars at opposition" (in en). 3 November 2005. 
  243. Sheehan, William (2 February 1997). "Appendix 1: Oppositions of Mars, 1901–2035". The Planet Mars: A History of Observation and Discovery. University of Arizona Press. 
  244. 244.0 244.1 "Mars Opposition | Mars in our Night Sky" (in en). 
  245. "EarthSky | Why is Mars sometimes bright and sometimes faint?" (in en-US). 2021-10-05. 
  246. Rao, Joe (22 August 2003). "NightSky Friday—Mars and Earth: The Top 10 Close Passes Since 3000 B.C.". 
  247. "Slide 2 Earth Telescope View of Mars". The Red Planet: A Survey of Mars. Lunar and Planetary Institute. 
  248. Rabkin, Eric S. (2005). Mars: A Tour of the Human Imagination. Westport, Connecticut: Praeger. pp. 9–11. ISBN 978-0-275-98719-0. 
  249. Thompson, Henry O. (1970). Mekal: The God of Beth-Shan. Leiden, Germany: E. J. Brill. p. 125. 
  250. Novakovic, B. (2008). "Senenmut: An Ancient Egyptian Astronomer". Publications of the Astronomical Observatory of Belgrade 85: 19–23. Bibcode2008POBeo..85...19N. 
  251. North, John David (2008). Cosmos: an illustrated history of astronomy and cosmology. University of Chicago Press. pp. 48–52. ISBN 978-0-226-59441-5. 
  252. Swerdlow, Noel M. (1998). "Periodicity and Variability of Synodic Phenomenon". The Babylonian theory of the planets. Princeton University Press. pp. 34–72. ISBN 978-0-691-01196-7. 
  253. Cicero, Marcus Tullius (1896). De Natura Deorum. London: Methuen. 
  254. Stephenson, F. Richard (November 2000). "A Lunar Occultation of Mars Observed by Aristotle" (in en). Journal for the History of Astronomy 31 (4): 342–344. doi:10.1177/002182860003100405. ISSN 0021-8286. Bibcode2000JHA....31..342S. 
  255. Harland, David Michael (2007). Cassini at Saturn: Huygens results. p. 1. ISBN 978-0-387-26129-4. 
  256. McCluskey, S. C. (1998), Astronomies and Cultures in Early Medieval Europe, Cambridge: Cambridge University Press, pp. 20–21, ISBN 978-0-521-77852-7 
  257. Needham, Joseph; Ronan, Colin A. (1985). The Shorter Science and Civilisation in China: An Abridgement of Joseph Needham's Original Text. 2 (3rd ed.). Cambridge University Press. p. 187. ISBN 978-0-521-31536-4. 
  258. de Groot, Jan Jakob Maria (1912). "Fung Shui". Religion in China – Universism: A Key to the Study of Taoism and Confucianism. American Lectures on the History of Religions, volume 10. G. P. Putnam's Sons. p. 300. OCLC 491180. 
  259. Crump, Thomas (1992). The Japanese Numbers Game: The Use and Understanding of Numbers in Modern Japan. Nissan Institute/Routledge Japanese Studies Series. Routledge. pp. 39–40. ISBN 978-0-415-05609-0. 
  260. Hulbert, Homer Bezaleel (1909). The Passing of Korea. Doubleday, Page & Company. p. 426. OCLC 26986808. 
  261. Taton, Reni (2003). Reni Taton. ed. Planetary Astronomy from the Renaissance to the Rise of Astrophysics, Part A, Tycho Brahe to Newton. Cambridge University Press. p. 109. ISBN 978-0-521-54205-0. 
  262. Frautschi, Steven C.; Olenick, Richard P.; Apostol, Tom M.; Goodstein, David L. (2007). The Mechanical Universe: Mechanics and Heat (Advanced ed.). Cambridge [Cambridgeshire]: Cambridge University Press. ISBN 978-0-521-71590-4. OCLC 227002144. 
  263. Hirshfeld, Alan (2001). Parallax: the race to measure the cosmos. Macmillan. pp. 60–61. ISBN 978-0-7167-3711-7. 
  264. Breyer, Stephen (1979). "Mutual Occultation of Planets". Sky and Telescope 57 (3): 220. Bibcode1979S&T....57..220A. 
  265. Peters, W. T. (1984). "The Appearance of Venus and Mars in 1610". Journal for the History of Astronomy 15 (3): 211–214. doi:10.1177/002182868401500306. Bibcode1984JHA....15..211P. 
  266. Sheehan, William (1996). "2: Pioneers". The Planet Mars: A History of Observation and Discovery. Tucson: University of Arizona. Retrieved 16 January 2010. 
  267. Milner, Richard (2011-10-06). "Tracing the Canals of Mars: An Astronomer's Obsession" (in en). 
  268. 268.0 268.1 Sagan, Carl (1980). Cosmos. New York City: Random House. p. 107. ISBN 978-0-394-50294-6. 
  269. Basalla, George (2006). "Percival Lowell: Champion of Canals". Civilized Life in the Universe: Scientists on Intelligent Extraterrestrials. Oxford University Press US. pp. 67–88. ISBN 978-0-19-517181-5. 
  270. Dunlap, David W. (1 October 2015). "Life on Mars? You Read It Here First.". The New York Times. 
  271. Maria, K.; Lane, D. (2005). "Geographers of Mars". Isis 96 (4): 477–506. doi:10.1086/498590. PMID 16536152. 
  272. Perrotin, M. (1886). "Observations des canaux de Mars" (in fr). Bulletin Astronomique. Série I 3: 324–329. Bibcode1886BuAsI...3..324P. 
  273. Zahnle, K. (2001). "Decline and fall of the Martian empire". Nature 412 (6843): 209–213. doi:10.1038/35084148. PMID 11449281. 
  274. Koch, Ulla Susanne (1995) (in en). Mesopotamian Astrology: An Introduction to Babylonian and Assyrian Celestial Divination. Museum Tusculanum Press. pp. 128–129. ISBN 978-87-7289-287-0. 
  275. Cecilia, Ludovica (2019-11-06). "A Late Composition Dedicated to Nergal". Altorientalische Forschungen 46 (2): 204–213. doi:10.1515/aofo-2019-0014. ISSN 2196-6761. 
  276. Reid, James (2011). "An Astronomer's Guide to Holst's The Planets". Sky and Telescope 121 (1): 66. Bibcode2011S&T...121a..66R. 
  277. "Solar System Symbols". 
  278. Jones, Alexander (1999). Astronomical papyri from Oxyrhynchus. pp. 62–63. ISBN 9780871692337. 
  279. Eschner, Kat. "The Bizarre Beliefs of Astronomer Percival Lowell" (in en). 
  280. Fergus, Charles (2004). "Mars Fever". Research/Penn State 24 (2). Retrieved 2 August 2007. 
  281. Plait, Philip C. (2002). Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing 'Hoax'. New York: Wiley. pp. 233–234. ISBN 0-471-40976-6. OCLC 48885221. 
  282. Lightman, Bernard V. (1997). Victorian Science in Context. University of Chicago Press. pp. 268–273. ISBN 978-0-226-48111-1. 
  283. Schwartz, Sanford (2009). C. S. Lewis on the Final Frontier: Science and the Supernatural in the Space Trilogy. Oxford University Press US. pp. 19–20. ISBN 978-0-19-537472-8. 
  284. Buker, Derek M. (2002). The science fiction and fantasy readers' advisory: the librarian's guide to cyborgs, aliens, and sorcerers. ALA readers' advisory series. ALA Editions. p. 26. ISBN 978-0-8389-0831-0. 
  285. Rabkin, Eric S. (2005). Mars: a tour of the human imagination. Greenwood Publishing Group. pp. 141–142. ISBN 978-0-275-98719-0. 
  286. Crossley, Robert (2011-01-03) (in en). Imagining Mars: A Literary History. Wesleyan University Press. pp. xiii-xiv. ISBN 978-0-8195-7105-2. 

External links