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The millimetre (SI symbol: mm) is a unit of length in the metric system equal to 10 −3 metres ( 1 / 1 000 m = 0.001 m). To help compare different orders of magnitude , this section lists lengths between 10 −3 m and 10 −2 m (1 mm and 1 cm).
Mars hosts many enormous extinct volcanoes (the tallest is Olympus Mons, 21.9 km or 13.6 mi tall) and one of the largest canyons in the Solar System (Valles Marineris, 4,000 km or 2,500 mi long). Geologically , the planet is fairly active with marsquakes trembling underneath the ground, dust devils sweeping across the landscape, and cirrus clouds .
The sixteen equatorial quadrangles are the smallest, with surface areas of 4,500,000 square kilometres (1,700,000 sq mi) each, while the twelve mid-latitude quadrangles each cover 4,900,000 square kilometres (1,900,000 sq mi). The two polar quadrangles are the largest, with surface areas of 6,800,000 square kilometres (2,600,000 sq mi) each.
For example, if a TNO is incorrectly assumed to have a mass of 3.59 × 10 20 kg based on a radius of 350 km with a density of 2 g/cm 3 but is later discovered to have a radius of only 175 km with a density of 0.5 g/cm 3, its true mass would be only 1.12 × 10 19 kg.
The Medusae Fossae Formation is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. Sometimes the formation appears as a smooth and gently undulating surface; however, in places it is wind-sculpted into ridges and grooves. [ 18 ]
Mars has a higher scale height of 11.1 km than Earth (8.5 km) because of its weaker gravity. [5] The theoretical dry adiabatic lapse rate of Mars is 4.3 °C km −1 , [ 131 ] but the measured average lapse rate is about 2.5 °C km −1 because the suspended dust particles absorb solar radiation and heat the air. [ 2 ]
Mars has an orbit with a semimajor axis of 1.524 astronomical units (228 million km) (12.673 light minutes), and an eccentricity of 0.0934. [ 1 ] [ 2 ] The planet orbits the Sun in 687 days [ 3 ] and travels 9.55 AU in doing so, [ 4 ] making the average orbital speed 24 km/s.
For example, the peak discharge required to carve the 28-km-wide Ares Vallis is estimated to have been 14 million cubic metres (500 million cu ft) per second, over ten thousand times the average discharge of the Mississippi River. [41] Mars Orbital Laser Altimeter (MOLA) derived image of Planum Boreum. Vertical exaggeration is extreme.