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Mercury, being the closest to the Sun, with a weak magnetic field and the smallest mass of the recognized terrestrial planets, has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10 −14 bar (1 nPa). [2]
The radius of Mercury's core is estimated to be 2,020 ± 30 km (1,255 ± 19 mi), based on interior models constrained to be consistent with a moment of inertia factor of 0.346 ± 0.014. [9] [33] Hence, Mercury's core occupies about 57% of its volume; for Earth this proportion is 17%. Research published in 2007 suggests that Mercury has a molten ...
[4] [5] Mercury's surface shows intercrater plains, basins, smooth plains, craters, and tectonic features. Mercury's oldest surface is its intercrater plains, [4] [6] which are present (but much less extensive) on the Moon. The intercrater plains are level to gently rolling terrain that occur between and around large craters.
The current Venusian atmosphere has only ~200 mg/kg H 2 O(g) in its atmosphere and the pressure and temperature regime makes water unstable on its surface. Nevertheless, assuming that early Venus's H 2 O had a ratio between deuterium (heavy hydrogen, 2H) and hydrogen (1H) similar to Earth's Vienna Standard Mean Ocean Water of 1.6×10 −4, [7] the current D/H ratio in the Venusian atmosphere ...
Mercury – Gravity Anomalies – mass concentrations (red) suggest subsurface structure and evolution. Like the Earth, Moon and Mars, Mercury's geologic history is divided into eras. From oldest to youngest, these are: the pre-Tolstojan, Tolstojan, Calorian, Mansurian, and Kuiperian. Their ages are based on relative dating only. [14]
Caloris Planitia / k ə ˈ l ɔːr ɪ s p l ə ˈ n ɪ ʃ (i) ə / is a plain within a large impact basin on Mercury, informally named Caloris, about 1,550 km (960 mi) in diameter. [1] It is one of the largest impact basins in the Solar System.
List of geological features on Mercury is an itemization of mountains, valleys, craters and other landform features of the planet Mercury.Different types of features are named after different things: Mercurian ridges are called dorsa, and are named after astronomers who made detailed studies of the planet; valleys are called valles, and are named after ancient abandoned cities, towns, and ...
Due to the proximity of Mercury to the Sun, Mercury on average receives an energy flux from the Sun that is about 7 times the solar constant, but may reach nearly 11 times at maximum and about 4.5 times at minimum. The Sun will have an angular diameter of 1.733 to 1.142°.