Distance from Sun: 36,000,000 miles

Diameter: 3,032 miles or about 1/3 that of Earth

Number of moons: 0

Length of year: 88 Earth days

Temperature: -279°F to 800°F

Mercury is a ball of rock with an iron core.

Mercury is the planet closest to the Sun. Its greyish surface is covered with craters made by objects that hit the planet. Mercury has no atmosphere and no water, and the surface would be very unpleasant to be on. The side of the planet that faces the Sun gets very hot, and the side that faces away from the Sun gets very cold.

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