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
Sword and planet Mars" by Edgar Rice Burroughs originally serialized by "All-Story" in 1912 as "Under the Moons of Mars". The genre predates the mainstream popularity of science fiction proper, and does not necessarily feature any scientific rigor, being instead romantic tales of high adventure. For example, little thought is given to explaining why the environment of the alien planet is compatible with life from Earth, just that it does in order to allow the hero to move about and interact with the natives. Native technology will often break the known laws of physics. The genre tag "sword and planet" is constructed to