A astronomical symbol for Mars is a circle by using an arrow pointing northeast (Unicode: ♂). This symbol occurs as conventionalised representation of the shield & spear of the god Mars, & inside biology these are utilized as a sign for the male sex.

A Chinese, Korean, and Japanese cultures refer to a planet as the Fire Star, according to a Five Elements.

Mythology
Mars has sure as shooting been seen by skygazers since prehistoric days. It was known per Egyptians as "Her Deschel" or "the Red One." Among a Babylonians Mars was known as "Nirgal" or "the Star of Death". A Romans were a ones to give Mars its modern title, fallowing the God of War.

Physical characteristics
A red, fiery appearance of Mars is from either cast-irin oxide (rust) on its surface. Mars has lone a quarter the area of the Earth and only a single-ten percent a mass (though its surface area is around adequate to that of the Globe's dry land because Mars lacks oceans). A solar day (or "sol") in Mars is nigh a equivalent length when these are in Globe: Xxiv hours, 39 transactions, & 35.244 seconds.

Atmosphere
Mars' atmosphere is thin: a air pressure on the surface is only 750 pascals, about Cipher.75 percent of the norm olympic games. But, a scale height of the atmosphere is about Xi kilometer, somewhat higher than Globe's Sestet kilometer. A atmosphere in Mars is 95 percent carbon dioxide, 3 percent nitrogen, 1.6 percent argon, and traces of oxygen and water. Inside 2003, methane was apparently discovered in the atmosphere by Globe-depending telescopes, and even confirmed around March 2004 by the Mars Express Orbiter, present measurements state an norm methane concentration of astir 11±4 ppb by volume (see reference). A thinly atmosphere can't hang in to heat & is the drive of the frigidity on Mars (Twenty degrees Celsius or even 68 degrees Fahrenheit is astir when hot when it gets).

the presence of methane in Mars would exist as super intriguing, since as an unstable barking spiders it indicates that there must become (or even develop been inside a endure couple of centred years) a source of the flatulence on the planet. Volcanic activity, comet impacts and a being of life in the form of microorganisms such as methanogens are among conceivable however until now unproved sources. A methane appears to occur inside patches, which suggests that these are existence apace broken down (and then is presumptively besides high-pressure existence freed to the atmosphere) prior to it has period to get uniformly distributed in the atmosphere. Plans come nowadays existence manufactured to search more 'companion' gases that might indicate which sources come virtually all belike; in the Globe's oceans biological mc2h6 production tends to become accompanied by ethane, while volcanic methane is accompanied by sulfur dioxide.

More aspects of the Martian atmosphere come likewise super dynamic. within a wintertime months once a poles come in family medicine darkness, the surface gets therefore cold that up to 25% of the entire atmosphere condenses retired into meters heavy slabs of CO₂ ice. Once a poles come over again studied to sunshine a CO_Two ice sublimates, creating tremendous winds that sweep off a poles when convenient when 250 mph. These seasonal actions conveyance big numbers of dust & water vapour produce to Globe-such as frost and large cirrus clouds. These clouds [http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20041213a/merb_sol290_clouds-B313R1_br.jpg] of a water supply-ice were photographed per Chance rover around 2004.

Recently, grounds to believe has been found suggesting that Mars can be warming on the short term [http://news.bbc.co.uk/2/hi/science/nature/4266474.stm]; nonetheless, these are today cooler than it was in the 1970's [http://catdynamics.blogspot.com/2005/09/climate-science-mars-and-politics.html].

Geology
A surface of Mars is primarily composed of basalt and andesite rock, covered in numerous pages by meters or even further of the dust when amercement when talcum powder.

Observations of the magnetic fields on Mars per Mars Global Surveyor spacecraft have revealed that area of the planet's crust has been magnetized around alternating elastic, usually with measurements of Century miles wide by 600 miles hanker (160 kilometer by Thou kilometer), in the similar pattern to people noticed on the ocean bottom of Globe. Of these interesting theory, published within 1999 is that these bands can be grounds to believe of the preceding operation of plate tectonics on Mars, although this has yet to exist as proven [http://photojournal.jpl.nasa.gov/catalog/PIA02008]. Newly findings, published within October 2005 trend lines this theory, & seem to imply an early era of tectonic activity similar to it detected olympian games ascribable sea-floor disseminating [http://www.pnas.org/cgi/content/full/102/42/14970#SEC5]. In case admittedly, a processes included might use helped to sustain an Globe-prefer atmosphere by transporting carbon rich rocks to a surface, when the presence of a magnetic field would use helped to protect the planet from either cosmic radiation. More explanations stand besides been proposed.

Amongst a findings from either a Chance rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. A spheres come exclusively two or three millimeters from side to side & come believed to use at times formed when rock deposits under watery conditions billions of years ago. More minerals use at times likewise been observed containing forms of s, iron or even atomic number 35 like jarosite. This & more grounds to believe led the class action of L man of science to conclude in the December 9, 2004 edition of the journal Science that "Liquid water was once intermittently present at the Martian surface at Meridiani, and at times it saturated the subsurface. Because liquid water is a key prerequisite for life, we infer conditions at Meridiani may have been habitable for some period of time in Martian history". On a paired side of the planet the mineral goethite, which (unlike hematite) forms single in the presence ofwater system system, along by owning more grounds to believe of water, has besides been uncovered per Spirit rover in the "Columbia Hills".

Inside 1996, researchers researching the meteorite (ALH84001) believed to have originated from either Mars reported features which it attributed to microfossils left by life in Mars. As of 2005, this interpretation remains controversial with there are no consensus with emerged.

Topography
A duality of Martian topography is striking: northern plains flattened by lava flows direct contrast by using a southern upl&, faveolate and cratered by ancient impacts. A surface of Mars when seen from either Globe is consequently divided into deuce kinda areas, by having differing albedo. A blanch plains covered by owning dust & sand rich around ruddy cast-iron oxides were it used to be that thought of when Martian 'continents' & given list rather Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). A dark features were thought to exist as seas, hence their list Mare Erythraeum, Mare Sirenum and Aurorae Sinus. A big dark feature seen from either Globe is Syrtis Major.

Mars has polar icecap that contain frozen h2o & carbon dioxide that change sustaining a Martian seasons — the carbon dioxide ice sublimates withinside summertime, uncovering a surface of superimposed rocks, & forms once again in wintertime. An out shield volcano, Olympus Mons (Mount Olympus), is at 27 km the highest mountain in the solar system. These are within the huge highland region known as Tharsis, containing several big volcanos. Understand list of mountains on Mars. Mars likewise has a solar body's big canon formulas, Valles Marineris or the Mariner Valley, which is 400Klick hanker & Septenary klick deep. Mars is as well scarred by the total of impact craters. A largest one is the Hellas impact basin, covered with lightly red sand. Understand list of craters on Mars.

The difference between Mars' greatest & last-place points is about 31 kilometre (from either a top of Olympus Mons at an altitude of Twenty-seven kilometer to a bottom of the Hellas impact basin at an altitude of Quartet kilometre in the image below the data point). Compared to, the difference between Globe's greatest & moo points (Mount Everest and the Mariana Trench) is only Xix.Vii kilometre. Conjunctive using a planets' different radii, this means Mars is about threefold "rougher" than Globe.

A International Astronomical Union's Working Group for Planetary System Nomenclature is responsible for naming Martian surface features.

More notes:

Zero elevation: Since Mars has there are there is no oceans & hence no 'sea level', the zero-elevation surface or even mean gravity surface must be selected. A datum for Mars is defined by a for-degree & for-the correct sequence ball-shaped harmonic gravity field, by having the zero altitude defined per 610.Five Pa (Captain hicks.105 mbar) atmospheric pressure surface (or so Zero.6% of Globe's) at the temperature of 273.Sixteen K. This pressure & temperature correspond to the triple point of water.

Zero meridian: Mars' equator is defined by its rotation, however a location of its Prime Meridian was specified, as was Globe's, designedly of an arbitrary point which was accepted by late observers. A German stargazer Wilhelm Beer and Johann Heinrich Mädler selected a little round feature as a point of reference once it produced a foremost orderly chart of Mars features inside 1830-32. Inside 1877, their choice wwhen adopted as a prime meridian per Italian uranologist Giovanni Schiaparelli when he began work in his notable maps of Mars. When a space vehicle Mariner 9 provided extensive imagery of Mars around 1972, a little crater (in the future known as Airy-0), located in the Sinus Meridiani ('Middle Bay' or 'Meridian Bay') along a line of Beer & Mädler, was chosen by Merton Davies of the RAND Corporation to provide a additional exact definition of Cypher.Nought° longitude while he established the planetographic control point network.

Canals
Mars has an significant place inside individual imaginatiin due to the belief by a select few that life existed on Mars. These beliefs flow from primarily to observations by numerous in the 19th century popularized by Percival Lowell and Giovanni Schiaparelli. Schiaparelli known as these ascertained features canali, meaning trend lines in Italian. This wwhen popularly mistranslated as 'canals', & a myth of the Martian canals began. It were apparently unreal linear features on the surface that were asserted to become canals, & due to seasonal changes in the brightness of occasionally areas that were thought to exist as from either vegetation incubation. This bring about to many stories concerning Martians. A linear features come okay, known to become mostly non-wanting or even, within occasionally legal actions, dry ancient watercourses. A colour changes keep around been ascribed to sirocco.

Mars' moons

Each Phobos and Deimos are tidally locked with Mars, always pointing a equivalent face towards it. Since Phobos orbits in Mars sooner than a planet itself rotates, tidal forces come slowly however steadily decreasing its orbital radius. At occasionally point later Phobos is broken higher by gravitational forces (view Roche limit). Deimos, then again, is far plenty away that its orbit is existence slowly boosted instead.

Two satellites were found within 1877 by Asaph Hall, and come known as when a characters Phobos (panic/fear) and Deimos (terror/dread) who, around Greek mythology, accompanied their father the Greek god Ares into battle. Ares was known to the Romans as Mars, the god of war.

Equally seen from either Mars, Phobos has an angular diameter of between 8' (rising) & Xii' (overhead), patch Deimos has an angular across of astir Two'. A Sun's angular across, by counterpoint, is astir Xxi'.

The exploration of Mars
Independent article: Exploration of Mars

12 of spacecraft, including orbiters, landers, and rovers, have been sent to Mars per Soviet Union, the United States, Europe, and Japan to study a planet's surface, climate, & geographics. About 2-thirds of everthing ballistic capsule destined for Mars keep around failed within a single manner or an additional prior to complementary or even beginning their missions. A share of this high failure rate may be ascribed to technical indicator even problems, however plenty own either failing or misused communications for there is no apparent understanding that a few investigator half-jokingly speak of an Globe-Mars "Bermuda Triangle" or of a Great Galactic Ghoul which subsists on the diet of Mars probes, or even of the Mars Curse.

Among a virtually all successful missions come a Mars probe program, the Mariner and Viking programs, Mars Global Surveyor, Mars Pathfinder, and Mars Odyssey. Spherical Surveyor has taken pictures of gullies & rubble flow features that indicate there can be todays sources of liquid a water supply, similar to an aquifer, at or touching a surface of the planet. Mars Odyssey determined that there are immense deposits of a river ice in the upper tercet meters of Mars' regolith within 60° latitude of the south pole.

Around 2003, the ESA launched the Mars Express craft consisting of the Mars Express Orbiter and the lander Beagle 2. Mars Express Orbiter confirmed a presence of water supply ice & carbon dioxide ice at a planet's south pole. NASA got antecedently confirmed their presence at a northerly pole of Mars. Tries to email a Beagle Two failed & it was declared wasted within early February 2004.

As well around 2003, NASA launched a twin Mars Exploration Rovers named Spirit (MER-A) and Chance (MER-B). Two missions landed with success inside January 2004 & st& met or even exceeded everthing their targets; when the Ninety-day nominal mission wwhen planned, as of February 2005, their missions own been extended twice and it prove my point to go to science, although a select few mechanical faults use occurred. Among a virtually all important science go to has been grounds to believe of liquid a stream a bit of instance it used to be that at each landing web sites. Additionally, first, dust devils imaged from ground-level keep around been found moving through a surface of Mars by Spirit (MER-A). (Look at picture in the image below).

Early nomenclature
Although better remembered for mapping a Moon starting in 1830, Johann Heinrich Mädler and Wilhelm Beer were the 1st "areographers". It began hit by establishing conclusively that virtually all of the surface features were lasting, & pinned down Mars' rotation cycle. Within 1840, Mädler combined ten years of observations & drew a foremost map of Mars ever processed. Like than rendering list to the various markings it mapped, Beer & Mädler just intended the two by using letters; Meridian Bay (Sinus Meridiani) was so feature "a".

Across the next twenty years or even therefore, when instruments improved & a total of observers too increased, various Martian features acquired a hodge-podge of list. To give two or three of examples, Solis Lacus was known as a "Oculus" (a Eye), & Syrtis Major was usually referred to as a "Hourglass Sea" or even a "Scorpion". Within 1858, it was also dubbed a "Atlantic Canale" per Jesuit uranologist Angelo Secchi. Secchi commented that it "seems to play the role of the Atlantic which, on Earth, separates the Old Continent from the New" —this was a number 1 instance a fateful canale, which within Italian might mean either "channel" or even "canal", experienced been applied to Mars.

Inside 1867, Richard Anthony Proctor drew up the map of Mars depending, somewhat crudely, on the Rpm. William Rutter Dawes' earlier drawings of 1865, then a better ones available. Monitor explained his rules of language by expression, "I have applied to the different features the names of those observers who have studied the physical peculiarities presented by Mars." On this text come occasionally of his list, opposite by having people late projected by Schiaparelli: Kaiser Sea = Syrtis Major Lockyer Land = Hellas Independent Sea = Lacus Moeris Herschel Two Strait = Sinus Sabaeus Dawes Continent = Aeria & Arabia De La Rue Ocean = Mare Erythraeum Lockyer Sea = Solis Lacus Dawes Sea = Tithonius Lacus Madler Continent = Chryse, Ophir, Tharsis Maraldi Sea = Mares Sirenum & Cimmerium Secchi Continent = Memnonia Hooke Sea = Mare Tyrrhenum Cassini Land = Ausonia Herschel I personally Continent = Zephyria, Aeolis, Aethiopis Hind Land = Libya

Monitor's terminology has typically been criticized, primarily because then numbers of of his list honored English uranologist, however as well because he utilized numerous list supplementary than when. Particularly, Dawes appeared there is no fewer than six times (Dawes Ocean, Dawes Continent, Dawes Sea, Dawes Strait, Dawes Isle,& Dawes Forked Bay). However, Monitor's list are nin while forgoing charm, & for 100% their defect it were the foundation on which late stargazer would improve.

Observation of Mars

The "Ares Vallis" area as photographed by Mars Pathfinder (click for detailed description). Globe lives Mars each 780 years (or even 2 years + septenary weeks & 1 day) at the few feet away of astir 80,000,000 kilometer. Nevertheless, this varies because a orbits come elliptical. To a naked-eye observer, Mars commonly shows a distinct yellowness, orange or even carmine colour, & varies inside brightness to a higher degree any supplementary planet equally seen from either either Globe all over a course of its orbit, due to the fact that whenever uttermost out of the Globe these are more than 7 days after far from the latter when when these are nighest (& may be misused in the Sun's glare for months at once once least favorably placed). At its virtually all favourable days — which occur twice each 32 years, alternately at 15 & 17-season intervals, & universally between late July and late September — Mars shows the wealth of surface detail to a telescope. Especially noticeable, possibly at moo magnification, come a polar ice caps.

In August 27, 2003, at 9:51:13 UT, Mars made its nearest approach to Globe inside about 60,000 years: 55,758,006 kilometre (just about 35 million miles) forgoing Light-time correction. This close approach hap because Mars was 1 day from either opposition and about trio years from either its perihelion, making Mars particularly easy to watch from either Globe. A previous period it come and so close is figured to use at times get on September 12, 57,617 BC. Elaborated analysis of the solar technique's gravitative landscape forecasts an potentially nigher approach around 2287. All the same, to keep this around perspective, this record approach was sole an unnoticeably midget fraction to a lesser degree more recent close approaches that occur 4 days each 284 years. For example, a minimal few feet away in August 22 1924 was 0.37284 AU, compared to Zero.37271 AU in August 27 2003, and a minimal few feet away in August 24 2208 will be 0.37278 AU.

The transit of the Earth as seen from Mars will occur on November 10, 2084. At that period the Sun, a Globe & Mars is exactly inside a line. There are besides transits of Mercury and transits of Venus, and a moon Deimos is of sufficiently small angular diameter that its partial "eclipses" of the Sun are better considered transits (understand Transit of Deimos from Mars).

A just eclipse of Mars by Venus to be found was that of October Three, 1590, seen by M. Möstlin at Heidelberg.

Appearance

Martian meteorites
Main article: Martian meteorites

A handful of objects are known that are surely meteorites and may be of Martian origin. Two of them may show signs of ancient bacterial activity. On August 6, 1996 NASA announced that analysis of the ALH 84001 meteorite thought to have come from Mars, shows some features that may be fossils of single-celled organisms, although this idea is controversial.

In Solar System Research (March 2004, vol 38, page 97) it was suggested that the unique Kaidun meteorite, recovered from Yemen, may have originated on the Martian moon of Phobos.

On April 14, 2004, NASA revealed that a rock known as "Bounce", studied by the Mars Exploration Rover Opportunity, was similar in composition to the meteorite EETA79001-B, discovered in Antarctica in 1979. The rock may have been ejected from the same crater as the meteorite, or from another crater in the same area of the Martian surface.

Ice lakes

On 29 July 2005, the BBC reported that a visible ice lake had been discovered in a crater in the north polar region of Mars[http://news.bbc.co.uk/1/hi/sci/tech/4727847.stm]. Images of the crater, taken by the High Resolution Stereo Camera on board the European Space Agency's Mars Express spacecraft, clearly show a broad sheet of ice in the bottom of an unnamed crater located on Vastitas Borealis, a broad plain that covers much of Mars' far northern latitudes, at approximately 70.5° North and 103° East. The crater is 35 km (23 mi) wide and about 2 km (1.2 mi) deep.

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Life on Mars
Main article: Life on Mars

Evidence exists that the planet once was significantly more habitable than today, but the question whether living organisms ever actually existed there is an open one. Some researchers think that a certain rock which is believed to have originated on Mars - specifically, meteorite ALH84001 - does contain evidence of past biologic activity, but no consensus about these claims has been achieved so far and recent research indicates that the rock, since its creation several billion years ago, has never been exposed to temperatures for extended periods of time that would allow for liquid water.

The Viking probes carried experiments designed to detect microorganisms in Martian soil at their respective landing sites, and had some positive results, later denied by many scientists, resulting in ongoing controversy. Also, present biologic activity is one of the explanations that have been suggested for the presence of traces of methane within the Martian atmosphere, but other explanations not involving life are generally considered more likely.

If colonization is going to happen, Mars seems a likely choice due to its rather hospitable conditions (compared with other planets, it is most like Earth).

The Mars flag

In early 2000, a proposed Mars flag flew aboard the space shuttle Discovery. Designed by NASA engineer and Flashline Mars Arctic Research Station task force leader Pascal Lee and carried aboard by astronaut John Mace Grunsfeld, the flag consists of of three vertical bars of red, green, and blue, symbolizing the transformation of Mars from a barren planet (red) to one bearing sustainable life (green), and finally to a fully terraformed planet with open bodies of water. This design was suggested by the Kim Stanley Robinson science fiction trilogy Red Mars, Green Mars, and Blue Mars. While other designs have been proposed, the republican tricolor has been adopted by the Mars Society as its own official banner. In a statement released after the launch of the mission, the Society said that the flag "has today been honored by the vessel of the leading spacefaring united states olympian games," and added that "(i personally)t is fitting that this action occurred after it did: at the sunup of a fresh millenium."