Mercury
Mercury is the closest planet to the sun and due to its proximity it is not easily seen except during twilight.
For evey two orbits of the sun, Mercury completes three rotations about it's axis and up until 1965 it was thought that the same side of Mercury constantly faced the sun. Thirteen times a century Mercury can be obeserved from the Earth passing across the face of the sun in an event called a transit.
Mercury facts
- Moons: noon
- Orbit Distance: 57,909 227 km (0.39 AU)
- Diameter: 1,392 684 km
- Orbit period: 88 days
- Mass: 1.99 x 10^30 kg (333,060 Earths)
- Surface Temperature: -173° to 427°C
- First Record: 14th century BC
- Recorded By: Assyrian astronomers