The Solar System

Mars

The red planet: a cold desert world with the tallest volcano and the deepest canyon in the Solar System.

Mars
Mars from the Viking orbiters, with the vast canyon Valles Marineris across its face. Credit: NASA/JPL/USGS, Public domain (NASA).
Size
6,792 km across. About 53% as wide as Earth.
One year
687 Earth days
One day
24 h 40 min
Moons
Two, Phobos and Deimos
Spacecraft
The rovers Perseverance and Curiosity are exploring it now, watched over by orbiters from the USA, Europe, India, China and the UAE.

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