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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. The origin of both moons is unclear, although a popular theory states that they were asteroids captured into Martian orbit.
The atmosphere of Mars is colder than Earth’s owing to the larger distance from the Sun, receiving less solar energy and has a lower effective temperature, which is about 210 K (−63 °C; −82 °F). [2] The average surface emission temperature of Mars is just 215 K (−58 °C; −73 °F), which is comparable to inland Antarctica.
For the giant planets, the "radius" is defined as the distance from the center at which the atmosphere reaches 1 bar of atmospheric pressure. [ 11 ] Because Sedna and 2002 MS 4 have no known moons, directly determining their mass is impossible without sending a probe (estimated to be from 1.7x10 21 to 6.1×10 21 kg for Sedna [ 12 ] ).
[31] [32] Mars has twice as much iron oxide in its outer layer as Earth does, despite their supposed similar origin. It is thought that Earth, being hotter, transported much of the iron downwards in the 1,800 kilometres (1,118 mi) deep, 3,200 °C (5,792 °F ), lava seas of the early planet, while Mars, with a lower lava temperature of 2,200 °C ...
1995 photo of Mars showing approximate size of the polar caps. The planet Mars has two permanent polar ice caps of water ice and some dry ice (frozen carbon dioxide, CO 2).Above kilometer-thick layers of water ice permafrost, slabs of dry ice are deposited during a pole's winter, [1] [2] lying in continuous darkness, causing 25–30% of the atmosphere being deposited annually at either of the ...
Earth's average orbital distance is about 150 million km (93 million mi), which is the basis for the astronomical unit (AU) and is equal to roughly 8.3 light minutes or 380 times Earth's distance to the Moon. Earth orbits the Sun every 365.2564 mean solar days, or one sidereal year. With an apparent movement of the Sun in Earth's sky at a rate ...
Diameter: 2,300 km (1,400 mi) ... Hellas Planitia was one of the first Martian features discovered from Earth by ... Atmosphere of Mars e.g. pressure at floor of ...
Mars comes closer to Earth more than any other planet save Venus at its nearest—56 million km is the closest distance between Mars and Earth, whereas the closest Venus comes to Earth is 40 million km. Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the Sun and Mars. Extra-close ...