Hartley 2 as imaged by NASA's Wide-field Infrared Survey Explorer, or WISE. The comet, known officially as 103P/Hartley was discovered fairly recently, in 1986, by Malcolm Hartley in Siding Spring, Australia. It probably originated from an icy orbit close to that of Jupiter's, before something knocked it on a path toward the sun. Credit: NASA/JPL-Caltech/UCLA