Mercury

Mercury is known as the smallest planet in our solar system. It has a similar appearance to the moon: it is heavily cratered with smooth plains. It also has no atmosphere, and unlike the moon, it has an iron core. Mercury consists of approximately 70% metallic and 30% silicate material, leading to saying that Mercury's inner core is not nearly compressed as earth's core. Recent studies also show that Mercury's core consists of molten rock.

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Instead of having an atmosphere, mercury has a thin exosphere made up of atoms blasted off its surface by solar wind and striking micro meteoroids. Because of the extreme surface temperature of Mercury, the atoms quickly escape into space. There has been no wind erosion of the surface, and meteorites do not burn up do to friction, unlike other planetary atmospheres.

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