Solar eclipses on Mars Solar eclipses on Mars The two moons of Mars, Phobos and Deimos, are much smaller than the Moon, greatly reducing the frequency of solar eclipses on that planet. Neither moon's apparent diameter is large enough to cover the disk of the sun, and therefore they are annular solar eclipses and can also be considered transits. Due to the small size of Phobos (about ) and its rapid orbital motion, an observer on the surface of Mars would never experience a solar eclipse for longer than about thirty seconds. Phobos also takes only 7 hours 39 minutes to orbit Mars, while
Phobos monolith an imaging sub-contractor at NASA Johnson Space Center. Lan Fleming considered the possibility that the Phobos monolith may be artificial and not a geological feature or rock. The general vicinity of the monolith is a proposed landing site by Optech and the Mars Institute, for an unmanned mission to Phobos known as PRIME (Phobos Reconnaissance and International Mars Exploration). The PRIME mission would be composed of an orbiter and lander, and each would carry four instruments designed to study various aspects of Phobos' geology. At present, PRIME has not been funded and does not have a projected launch date. Former