Of all the moons in the Solar System, the one which orbits closest to its planet is the tiny Martian satellite, Phobos.

Phobos is 9,378 km 5,827 miles from the centre of Mars – which corresponds to 5,981 km 3,716 miles above the Martian surface.


Phobos is a small potato-shaped irregular moon, measuring 27 x 22 x 18 km (17 x 14 x 11 miles). It is dark and covered with dusty craters and is almost certainly an asteroid which was captured by Mars’ gravity many millions of years ago.

The Moon is 384, 400 km (238,855 miles) from the Earth (centre to centre) which corresponds to 376,284 km (233,812 miles) (surface to surface).



Using the surface-to-surface measurement, Phobos is roughly 60 times closer to Mars than the Moon is to Earth.