Phobos (moon) break up when it reaches approximately 2.1 Mars radii. When Phobos is eventually torn apart by tidal forces, a fraction of the debris will likely form a planetary ring around Mars, which may last from one million to one hundred million years. The origin of the Martian moons is still controversial. Phobos and Deimos both have much in common with carbonaceous C-type asteroids, with spectra, albedo, and density very similar to those of C- or D-type asteroids. Based on their similarity, one hypothesis is that both moons may be captured main-belt asteroids. Both moons have very circular orbits which lie
The Planet of Doubt The Planet of Doubt "The Planet of Doubt" is a science fiction short story by Stanley G. Weinbaum that was first published in the October 1935 issue of "Astounding Stories". It is Weinbaum's third story featuring Hamilton Hammond and Patricia Burlingame, a sequel to "Parasite Planet" and "The Lotus Eaters". Following his expedition to the night side of Venus, the Smithsonian Institution appoints Hamilton "Ham" Hammond to head an expedition to Uranus. In Weinbaum's version of the Solar System, all of the gas giants generate significant amounts of infrared radiation, enough to produce Earthlike environments on the inner moons of