Eyeing the Impact

All eyes were on the sky early in the morning of July 4, as NASA guided Deep Impact’s 820-pound probe into a 6.3-miles-per second collision with comet Temple I—the first direct encounter with a comet. The probe and its mother ship captured some breathtaking images of the comet’s nucleus and the resulting explosion, but they were not the only ones collecting data that night. More than 60 observatories watched from Earth, along with several more from space. “Here’s an event that everybody knew exactly to the second was coming, and all these impressive instruments were able to train themselves on it,” said Gary Melnick, senior astrophysicist at the Harvard-Smithsonian Center for Astrophysics.