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  2. Mercury (planet) - Wikipedia

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

    Mercury is the first planet from the Sun and the smallest in the Solar System. In English, it is named after the ancient Roman god Mercurius (Mercury), god of commerce and communication, and the messenger of the gods. Mercury is classified as a terrestrial planet, with roughly the same surface gravity as Mars.

  3. 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 ...

  4. Geology of Mercury - Wikipedia

    en.wikipedia.org/wiki/Geology_of_Mercury

    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 processes that shape the planet. It is analogous to the field of terrestrial geology. In planetary science, the term geology is used in its broadest sense to mean the study of ...

  5. Seasons on planets - Wikipedia

    en.wikipedia.org/wiki/Seasons_on_planets

    Seasons on planets. The start and end dates of a season on any planet of the Solar System depends on same factors valid on Earth, but which have different values on different planets: All these factors affect how much energy from Sun falls on all the points at a same given latitude (i.e. a parallel) on the planet during daytime; if such amount ...

  6. Apparent retrograde motion - Wikipedia

    en.wikipedia.org/wiki/Apparent_retrograde_motion

    Apparent retrograde motion is the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. Direct motion or prograde motion is motion in the same direction as other bodies. While the terms direct and prograde are equivalent in this context, the former is the ...

  7. Axial tilt - Wikipedia

    en.wikipedia.org/wiki/Axial_tilt

    In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbital plane. [1] It differs from orbital inclination. At an obliquity of 0 degrees, the two axes point in ...

  8. Terrestrial planet - Wikipedia

    en.wikipedia.org/wiki/Terrestrial_planet

    Terrestrial planet. The four terrestrial planets of the Solar System: Mercury and Venus. Earth and Mars. Not shown to scale. A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate, rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets ...

  9. 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 ...