Cosmic Scale
The Moon
Earth's moon · 384,400 km from Earth
How big is The Moon?
The Moon is about 3,475 km across.
See The Moon in 3D, at true scale
The Moon formed when a Mars-sized body struck the young Earth and the debris pulled itself together in orbit. It steadies our planet's tilt, raises the tides, and is the only world other than Earth that humans have stood on.
At a glance
| Diameter | 3,475 km |
|---|---|
| Mass | 7.34 × 10²² kg |
| Diameter compared with Earth | 0.273 × Earth |
| Distance | 384,400 km |
| Day and month | Both 27.3 days |
| Gravity | 17% of Earth's |
| Temperature | −173 to 127 °C |
Good to know
- Because its spin and orbit match, it keeps one face toward us; the far side was not seen until 1959.
- It drifts about 3.8 cm farther away each year, and Earth's days grow slightly longer as a result.
- Twelve people walked on it between 1969 and 1972. Their footprints will last millions of years.