Mercury revolves around the sun very quickly, but rotates around its axis very, very slowly. One day on Mercury (sunrise to sunrise) is longer than one year on Mercury (one orbit around the Sun).
Mercurian Year: A year on Mercury takes 87.97 Earth days; it takes 87.97 Earth days for Mercury to orbit the sun once.
Mercurian Sidereal Day: Each sidereal day on Mercury takes 58.65 Earth days; it takes Mercury 58.65 days (2/3's of its year) to rotate around its axis once. One day on Mercury seems to last two Mercurian years (or 176 Earth days), i.e., sunrise to sunrise. It is daytime for one Mercurian year, and nighttime for one Mercurian year. http://www.enchantedlearning.com
Friday, March 13, 2009
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