Mystery Spirals on Mars Finally Explained". Space.com. May 26, 2010. Archived from the original on April 3, 2012 . Retrieved May 26, 2010. Malik, Tariq (June 21, 2018). "Epic Dust Storm on Mars Now Completely Covers the Red Planet". Space.com. Archived from the original on February 5, 2022 . Retrieved June 21, 2018.

Phillips, Tony. "Mars is Melting, Science at NASA". Archived from the original on February 24, 2007 . Retrieved February 26, 2007. Webster, C. R.; etal. (2013). "Isotope ratios of H, C, and O in CO 2 and H2O of the Martian atmosphere" (PDF). Science. 341 (6143): 260–263. Bibcode: 2013Sci...341..260W. doi: 10.1126/science.1237961. PMID 23869013. S2CID 206548962. Archived (PDF) from the original on October 29, 2021 . Retrieved August 30, 2020. Di Renzo, M.; Urzay, J. (2018). "Aerodynamic generation of electric fields in turbulence laden with charged inertial particles". Nature Communications. 9 (1): 1676. Bibcode: 2018NatCo...9.1676D. doi: 10.1038/s41467-018-03958-7. PMC 5920100. PMID 29700300.Eden, H.F.; Vonnegut, B. (1973). "Electrical breakdown caused by dust motion in low-pressure atmospheres: considerations for Mars". Science. 180 (4089): 39–87. Bibcode: 1973Sci...180..962E. doi: 10.1126/science.180.4089.962. PMID 17735929. S2CID 38902776.

Researchers suspect much of the low northern plains of the planet were covered with an ocean hundreds of meters deep, though this theory remains controversial. [187] 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 protium to deuterium in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium (D/H = 9.3 ± 1.7 10 -4) is five to seven times the amount on Earth (D/H = 1.56 10 -4), 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. [188] Near the northern polar cap is the 81.4 kilometres (50.6mi) wide Korolev Crater, which the Mars Express orbiter found to be filled with approximately 2,200 cubic kilometres (530cumi) of water ice. [189] Francis Reddy. "Titan, Mars methane may be on ice". Astronomy Magazine. Archived from the original on September 27, 2007 . Retrieved March 16, 2007. Madeleine, J. et al. 2007. Mars: A proposed climatic scenario for northern mid-latitude glaciation. Lunar Planet. Sci. 38. Abstract 1778. Stone, Shane W.; Yelle, Roger V.; Benna, Mehdi; Lo, Daniel Y.; Elrod, Meredith K.; Mahaffy, Paul R. (November 13, 2020). "Hydrogen escape from Mars is driven by seasonal and dust storm transport of water". Science. 370 (6518): 824–831. Bibcode: 2020Sci...370..824S. doi: 10.1126/science.aba5229. ISSN 0036-8075. PMID 33184209. S2CID 226308137. Archived from the original on September 16, 2022 . Retrieved December 8, 2020. There have been regional changes around the south pole ( Planum Australe) over the past few Martian years. In 1999 the Mars Global Surveyor photographed pits in the layer of frozen carbon dioxide at the Martian south pole. Because of their striking shape and orientation these pits have become known as swiss cheese features. In 2001 the craft photographed the same pits again and found that they had grown larger, retreating about 3 meters in one Martian year. [135] These features are caused by the sublimation of the dry ice layer, thereby exposing the inert water ice layer. More recent observations indicate that the ice at Mars' south pole is continuing to sublimate. [136]

Facts about Mars

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. [150] Search for 'Missing' Carbon on Mars Cancelled". Space.com. November 26, 2015. Archived from the original on November 29, 2015 . Retrieved December 1, 2015. MIRA's Field Trips to the Stars Internet Education Program". Mira.org. Archived from the original on January 19, 2010 . Retrieved February 26, 2007. See also: Category:Surface features of Mars A MOLA-based topographic map showing highlands (light colours) dominating the Southern Hemisphere of Mars, lowlands (dark colours) the northern. Volcanic plateaus delimit regions of the northern plains, whereas the highlands are punctuated by several large impact basins.

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. [72] Almeida, Murilo P.; etal. (2008). "Giant saltation on Mars". PNAS. 105 (17): 6222–6226. Bibcode: 2008PNAS..105.6222A. doi: 10.1073/pnas.0800202105. PMC 2359785. PMID 18443302. A large doughnut shaped cloud appears in the north polar region of Mars around the same time every Martian year and of about the same size. [87] It forms in the morning and dissipates by the Martian afternoon. [87] The outer diameter of the cloud is roughly 1,600km (1,000mi), and the inner hole or eye is 320km (200mi) across. [88] The cloud is thought to be composed of water-ice, [88] so it is white in color, unlike the more common dust storms. Scientists have theorized 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 on Earth; these elements were probably pushed outward by the young Sun's energetic solar wind. [23] Curiosity rover touches down on Mars". CBS News. Archived from the original on August 7, 2013 . Retrieved August 6, 2012.

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Noachian period: Formation of the oldest extant surfaces of Mars, 4.5 to 3.5billion 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. Named after Noachis Terra. [35] Mischna, M. et al. 2003. On the orbital forcing of martian water and CO 2 cycles: A general circulation model study with simplified volatile schemes. J. Geophys. Res. 108. (E6). 5062. Fraser Cain (March 25, 2004). "Solving the Puzzle of Mars' Spiral Icecaps". Universe Today. Archived from the original on November 4, 2019 . Retrieved November 4, 2019. Calle, Carlos (2017). Electrostatic Phenomena in Planetary Atmospheres. Bristol: Morgan & Claypool Publishers.