Facts About Mercury
- Mercury has a diameter of approximately 3,030 miles (4,878 km)
- Mercury does not have any moons.
- Mercury has a molten core but we think that its a solid iron core with lava or magma.
- Mercury has large craters on its surface.
- Mercury is the second densest planet in the solar system and a little lighter than Mars.
- In 2008, NASA's Messenger spacecraft discovered water vapor in Mercury's atmosphere.