Phobos and its smaller neighbouring moon, Deimos – both discovered in 1877 – are two of the most perplexing worlds in the solar system. “They’re the only objects at this stage, in the solar system, for which we have pretty much no idea what they are,” says Pascal Lee at the SETI Institute in California. “We know what other moons are. We know asteroids and comets. Phobos and Deimos? No idea.”

#space #science #scicomm