With a diameter averaging about 7 miles, it's the smaller of Mars' 2 moons
... as the 
larger moon, Phobos, passed in front of the smaller one, Deimos, from ... Earth's 
moon is gigantic compared to Phobos and Deimos, with a diameter of ... much 
farther away  its average distance is 239,000 miles (384,600 km)... [DOC] [TLE] Mars' Moons: Facts About Phobos & Deimos - Space.com [PAR] Jun 27, 2016 ...