The Solar System

The Moon

Earth’s companion, a quarter of Earth’s width. It always keeps the same face towards us.

The Moon
The full Moon, mwedzi, with its dark lava plains and bright highlands. Credit: NASA/JPL/USGS, Public domain (NASA).
Size
3,475 km across. About 27% as wide as Earth.
One orbit
27.3 days to go round Earth
One day
29.5 Earth days, new Moon to new Moon
Moons
None
Spacecraft
Twelve Apollo astronauts walked on it (1969–1972). China’s Chang’e 6 brought back rock from the far side in 2024, and Artemis II flew four astronauts around it in April 2026.

Sizes and periods from NASA’s planetary fact sheets; moon counts from NASA Science.