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  2. Atmosphere of Mercury - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Mercury

    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 ...

  3. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.

  4. Mercury cycle - Wikipedia

    en.wikipedia.org/wiki/Mercury_cycle

    The mercury cycle is a biogeochemical cycle influenced by natural and anthropogenic processes that transform mercury through multiple chemical forms and environments. Mercury is present in the Earth's crust and in various forms on the Earth's surface. It can be elemental, inorganic, or organic. [1] Mercury exists in three oxidation states: 0 ...

  5. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, and after hydrogen and helium, it ...

  6. Atmosphere of Mars - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Mars

    The atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.85%), and argon (2%). [3] It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen, and noble gases. [3][5][2] The atmosphere of Mars is much thinner and colder than Earth's having a max ...

  7. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    Oxygen cycle refers to the movement of oxygen through the atmosphere (air), biosphere (plants and animals) and the lithosphere (the Earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. The oxygen cycle is the biogeochemical cycle of oxygen atoms between different ...

  8. Mercury (element) - Wikipedia

    en.wikipedia.org/wiki/Mercury_(element)

    Mercury (element) rhombohedral (hR1) Mercury is a chemical element; it has symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum (/ haɪˈdrɑːrdʒərəm / hy-DRAR-jər-əm) from the Greek words hydor 'water' and argyros 'silver', from which its chemical symbol is derived. [8]

  9. Atmosphere of the Moon - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_the_Moon

    The atmosphere of the Moon is a very sparse layer of gases surrounding the Moon. For most practical purposes, the Moon is considered to be surrounded by vacuum. The elevated presence of atomic and molecular particles in its vicinity compared to interplanetary medium, referred to as " lunar atmosphere " for scientific objectives, is negligible ...