Future astronauts looking up at the Martian night sky will see not one, but two moons gliding across the overhead sky.
This illustration shows the size comparison of the two moons, Diemos, at the far left and Phobos, as seen from the Martian surface, alongside with Earth's moon as it appears from the surface of Earth.
On August 1, NASA's Curiosity rover captured both moons flying across the overhead sky together. At the time the rover snapped the images, 7.5-mile-wide (12-kilometer-wide) Deimos was 12,800 miles (20,500 kilometers) in altitude, while 14-mile-wide (22-kilometer-wide) Phobos was much closer at only 3,900 miles (6,240 kilometers) from the rover.
In contrast, Earth's moon has a diameter of 2,159 miles (3,474 kilometers) and is on average 238,000 miles (380,000 kilometers) away from Earth.