Astro Watch : For 30 years, a large near-Earth asteroid wandered its lone, intrepid path, passing before the scrutinizing eyes of scientists while keeping something to itself: 3552 Don Quixote, whose journey stretches to the orbit of Jupiter, now appears to be a comet. The discovery resulted from an ongoing project led by researchers at Northern Arizona University using the Spitzer Space Telescope. Through a lot of focused attention and a little bit of luck, they found evidence of cometary activity that had evaded detection for three decades. “Its orbit resembled that of a comet, so people assumed it was a comet that had gotten rid of all its ice deposits,” said Michael Mommert, a post-doctoral researcher at NAU who was a Ph.D. student of professor Alan Harris at the German Aerospace Center (DLR) in Berlin at the time the work was carried out. What Mommert and an international team of researchers discovered, though, was that Don Quixote was not actually a dead comet—one that had shed the carbon dioxide and water that give comets their spectacular tails. Instead, the third-biggest near-Earth asteroid out there, skirting Earth with an erratic, extended orbit, is “sopping wet,” said NAU associate professor David Trilling. The implications ...