Crash Course After the discovery of comet Shoemaker-Levy 9 in March 1993, astronomers determined that it had broken into pieces and would crash into Jupiter. The first piece struck on July 16. Two days later fragment G, one of the largest, followed, sending a plume 1,800 miles (2,900 kilometers) above the clouds (far left). An hour and a half later, a ring of debris moved outward at a thousand miles an hour (1,610 kilometers an hour) toward leftovers of the collapsed plume (second from left). The debris was still visible three days later next to new material from fragment L (third from left). Five days after impact (far right) the scars remained, distorted by winds. It was the first view of a collision like the one that helped kill off Earth’s dinosaurs 65 million years ago. Image by Robin Evans and John T. Trauger, JPL; Heidi Hammel, SSI; Hubble Space Telescope Comet Science Team/NASA/STSCI From Exploring Space: The Universe in Pictures, 2004