Mercury
planet
The smallest planet and the closest to the Sun. It never strays more than 28° from it, so it is only visible low in the twilight sky.
Data
- Type
- planet
- Equatorial radius
- 2,440 km
- Orbital period
- 88 days
- Rotation period
- 58.6 days
- Distance
- 0.39 AU
- Moons
- 0
Observing tip
Look low above the horizon within half an hour of sunset or before sunrise. A telescope shows a tiny disc with a phase.