Mars Planet Information

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 Sun's Equator

Longitude of ascending node 49.562o

Argument of perihelion 286.537o

Satellites 2

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

min mean max

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 planet's 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 NASA's 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