You Couldn't Make This Up Dept: The Mystery of Mars' Moon Phobos Deepens

You Couldn't Make This Up Dept: The Mystery of Mars' Moon Phobos Deepens: "The origin of Mars' tiny moon, Phobos (fear in ancient Greek), is a mystery, but three theories are considered plausible. The first is that the moon is a captured asteroid; the second is that it formed in-situ as Mars formed below it, and the third is that Phobos formed later than Mars, from debris flung into martian orbit when a massive meteorite struck the Red Planet. A fourth, far more speculative and controversial (although thoroughly intriguing) theory is one that has been kicking around for decades: that Phobos is a artificial object in Mars orbit -in short, a 1.5-mile-long, extremely ancient and battered spacecraft."