The Moon
Natural Satellite
The Moon formed roughly 4.5 billion years ago from debris after a Mars-sized body, sometimes called Theia, struck early Earth. It is gravitationally locked, always showing the same face to Earth, and drifts about 3.8 centimeters farther away each year.
Field Notes
- The Moon is slowly spiraling away from Earth at about 3.8 cm per year.
- Its gravity is the primary driver of Earth's ocean tides.
- It is tidally locked, so the same hemisphere always faces Earth.
| Planet Specifications | |
|---|---|
| Radius | 1,737 km |
| Mass | 7.347 × 10²² kg |
| Distance from Sun | 384,400 km from Earth |
| Rotation Speed | 16.65 km/h |