What is Known About Mercury?

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Mercury is the innermost planet of our Solar System and has been once visited by a spacecraft, Mariner 10 in 1974. Photographs show Mercury to be atmosphere less and cratered, much like our Moon. Mercury's weak gravity cannot hold on to any gas to form an atmosphere. It rotates much slower than the Earth and takes two months to pass from sunrise to sunset. Being nearer to the Sun, it's day temperature reaches 4500C while the long nights are icy cold with the temperature of- 1700C. It is believed that a huge body must have crashed into Mercury several thousand million years ago causing a circular area 1,300 Km across, known as the Coloris Basin. Mercury has a very elliptical orbit around the Sun. It's distance from the Sun changes from 70 million Km when farthest away to only 46 million Km when nearest.

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