How many moons does Mars have?

2 known moons.

Mars has 2 known moons as of September 2026, according to NASA and the JPL Solar System Dynamics group.

The named moons

Sorted by size. Distance is the average distance from the centre of Mars.

Moon	Diameter (miles / km)	Distance (miles / km)	One orbit	Discovered
Phobos	13.7 / 22	5,830 / 9,376	8 hours	1877, Asaph Hall
Deimos	7.5 / 12	14,600 / 23,463	1.263 days	1877, Asaph Hall

Why the number keeps changing

Big moons were found centuries ago through telescopes. The small ones, often only a few kilometres across, are found today by long camera exposures on the largest telescopes and by spacecraft. Each new batch is announced by the Minor Planet Center, so the count goes up in jumps. That is why every count on this site carries a date.

Other moon counts

Data: NASA Science and the JPL Solar System Dynamics satellite table, as of September 2026. The full table is available as moons.json.