Planet Facts

1. Mercury is the eighth largest planet (or second smallest) in the Solar System.

2. The orbital speed of Mercury is 47.8 km/sec

3. Mercury has no atmosphere and no known satellites.

4. The diameter of Planet Mercury is 4,878 km

5. The only visit to Mercury was made by the Mariner 10 spacecraft in 1974.

6. Mercury, often identified with the Greek god, Hermes, is the messenger of the gods in Roman mythology. Mercury is often characterized with winged sandals.

7. A year in Mercury is equal to 87.97 Earth Days

8. A day in Mercury is equal to 58.65 Earth Days