Video:Planet Profile: Mercurywith Nick Greene
Named after the Roman god of commerce, travel and thievery, Mercury is the closest planet to the sun and the eighth largest. Here are some more facts about Mercury.See Transcript
Transcript:Planet Profile: Mercury
Mercury BasicsNamed after the Roman god of commerce, travel and thievery, Mercury is the closest planet to the sun and the eighth largest. Mercury's existence has been known of since before the third century BC. The Greeks gave it two names: Apollo, for when it appeared as a morning star, and Hermes, when it came as an evening star. Mercury has a large iron core which is most likely at least partially molten. The silicate outer shell is only 500 to 600 km thick. It actually has a very thin atmosphere made up of atoms blasted off its surface by the solar wind. Due to the heat of the planet, these atoms quickly escape into space.
Additional Mercury DataMercury is a planet of extremes. Temperature variations swing from 90 to 700 Kelvin, which is about -297 degrees Fahrenheit to 801 degrees Fahrenheit. Mercury also has a very eccentric orbit; at perihelion, it is only 46 million km from the sun, but at aphelion, it is 70 million. Mercury has no known moons or satellites. The planet has a mean radius of 2439.7 km and mass of 0.055 Earth masses. Its density is 5.43 grams per cubic centimeter and gravity is 0.376 times Earth's gravity. Mercury's orbit period is 87.97 Earth days and rotation period is 58.65 Earth days. Semi-major axis of orbit is 0.387 au and eccentricity of orbit is 0.206.
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