Our Moon
The Moon
3,474 km across · orbits in 27.3 days — the fifth-largest moon in the solar system and the only world beyond Earth that humans have walked on.
The Moon is slowly drifting away from us at about 3.8 cm a year, and it always shows the same face because its rotation is locked to its orbit. See the Moon tab for tonight’s phase and the lunar atlas.
The Planet Itself
Diameter
12,742 km
The yardstick — 1 Earth
Day length
23h 56m
One true rotation
Year
365.26 days
One trip around the Sun
Earth is the only planet not named for a Roman god, and the only place in the catalogue you are standing on. From space its defining feature is liquid water — oceans cover 71% of the surface, and the thin blue atmosphere that keeps them liquid is just 100 km deep.