Moons of Mars 0.07. If viewed from Mars's surface near its equator, full Phobos looks about one third as big as a full moon on Earth. It has an angular diameter of between 8' (rising) and 12' (overhead). Due to its close orbit, it would look smaller when the observer is further away from the Martian equator, and is below the horizon and thus invisible when viewed from Mars's polar ice caps. Deimos looks more like a bright star or planet for an observer on Mars, only slightly bigger than Venus looks from Earth; it has an angular diameter of about 2'. The
Phobos monolith astronaut Buzz Aldrin has spoken about the Phobos monolith and his support for a mission to Phobos. The object appears in Mars Global Surveyor images SPS252603 and SPS255103, dated 1998. The object is unrelated to another monolith located on the surface of Mars, which NASA noted as an example of a common surface feature in that region. Phobos monolith The Phobos monolith is a large rock on the surface of Mars's moon Phobos. It is a boulder about across and tall. A monolith is a geological feature consisting of a single massive piece of rock. Monoliths also occur naturally on