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Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time; it does have a tenuous surface-bounded exosphere [89] at a surface pressure of less than approximately 0.5 nPa (0.005 picobars). [4]
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]
Caravaggio is an example of a Peak ring impact basin on Mercury. Several areas on Mercury are extremely dark, such as a small crater within Hemingway crater in the lower right. The geology of Mercury is the scientific study of the surface, crust, and interior of the planet Mercury. It emphasizes the composition, structure, history, and physical ...
A layer of diamonds up to 18 kilometers (11 miles) thick could be tucked below the surface of Mercury, the solar system’s smallest planet and the closest to the sun, according to new research. ...
The Mariner 10 mission (1974) mapped about half the surface of Mercury. On the basis of that data, scientists have a first-order understanding of the geology and history of the planet. [4] [5] Mercury's surface shows intercrater plains, basins, smooth plains, craters, and tectonic features.
Mercury, Ceres and several large natural satellites, such as the Moon, Europa, and Ganymede, have exospheres without a denser atmosphere underneath, [3] referred to as a surface boundary exosphere. [4] Here, molecules are ejected on elliptic trajectories until they collide with the surface. Smaller bodies such as asteroids, in which the ...
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 ...
The environment on Mercury also differs substantially from the Moon. For one thing, it is significantly hotter in the day (diurnal surface temperature ~100 °C for the Moon, ~425 °C on Mercury) and colder at night, which may alter the products of space weathering. In addition, because of its location in the Solar System, Mercury is subjected ...