... Martian Moon Phobos from MGS . ... Why is Phobos so dark? Phobos, the largest and innermost of two Martian moons, is the darkest moon in the entire Solar System. ... Likely, within a few million years, the intense light from bright stars will have boiled it away completely. ... It is still not known why the Sun's light is missing some colors. Shown above are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device. ... Galaxies in the GOODS . ...