Mars Planet Information
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Mars
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For other uses, including the Roman god, see Mars (disambiguation).
Mars Astronomical symbol of Mars The planet Mars
Mars as seen by the Hubble Space Telescope
Orbital characteristics[1]
Epoch J2000
Aphelion
249,209,300 km
1.665861 AU
Perihelion
206,669,000 km
1.381497 AU
Semi-major axis
227,939,100 km
1.523679 AU
Eccentricity
0.093315
Orbital period
686.971 day
1.8808 Julian years
668.5991 sols
Synodic period
779.96 day
2.135 Julian years
Average orbital speed
24.077 km/s
Inclination
1.850o
5.65o to Suns Equator
Longitude of ascending node
49.562o
Argument of perihelion
286.537o
Satellites
Physical characteristics
Equatorial radius
3,396.2 ± 0.1 km[2][3]
0.533 Earths
Polar radius
3,376.2 ± 0.1 km[2][3]
0.531 Earths
Flattening
0.00589 ± 0.00015
Surface area
144,798,500 kmІ
0.284 Earths
Volume
1.6318Ч1011 kmÑ-
0.151 Earths
Mass
6.4185Ч1023 kg
0.107 Earths
Mean density
3.934 g/cmÑ-
Equatorial surface gravity
3.69 m/sІ
0.376 g
Escape velocity
5.027 km/s
Sidereal rotation
period
1.025957 day
24.62296 h
Equatorial rotation velocity
868.22 km/h
Axial tilt
25.19o
North pole right ascension
21 h 10 min 44 s
317.68143o
North pole declination
52.88650o
Albedo
0.15
Surface temp.
Kelvin
Celsius
mean
186 K
227 K
268 K[5]
−87 oC
−46 oC
−5 oC
Apparent magnitude
+1.8 to -2.91[4]
Angular diameter
3.5″ — 25.1″[4]
Adjectives
Martian
Atmosphere
Surface pressure
0.7-0.9 kPa
Composition
95.72% Carbon dioxide
2.7% Nitrogen
1.6% Argon
0.2% Oxygen
0.07% Carbon monoxide
0.03% Water vapor
0.01% Nitric oxide
2.5 ppm Neon
300 ppb Krypton
130 ppb Formaldehyde
80 ppb Xenon
30 ppb Ozone
10 ppb Methane
Note: This article contains special characters.
Mars (pronounced /ˈmɑrz/) is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the “Red Planet” because of its reddish appearance as seen from Earth.
Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. In addition to its geographical features, Mars rotational period and seasonal cycles are likewise similar to those of Earth.
Until the first flyby of Mars by Mariner 4 in 1965, it was speculated that there might be liquid water on the planets surface. This was based on observations of periodic variations in light and dark patches, particularly in the polar latitudes, which looked like seas and continents, while long, dark striations were interpreted by some observers as irrigation channels for liquid water. These straight line features were later proven not to exist and were instead explained as optical illusions. Still, of all the planets in our Solar System other than Earth, Mars is the most likely to harbor liquid water, and perhaps life.
Mars is currently host to three functional orbiting spacecraft: Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter. This is more than any planet in the Solar System except Earth. The surface is also home to the two Mars Exploration Rovers (Spirit and Opportunity). Geological evidence gathered by these and preceding missions suggests that Mars previously had large-scale water coverage, while observations also indicate that small geyser-like water flows have occurred in recent years.[6] Observations by NASAs Mars Global Surveyor show evidence that parts of the southern polar ice cap have been receding.[7]
Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Martian Trojan asteroid. Mars can be seen from Earth with the naked eye. Its apparent magnitude reaches −2.9,[4] a brightness