Tom Gehrels (1925 – 2011), was an American astronomer, Professor Planetary Sciences, and Astronomer at the University of Arizona, Tucson. With co-workers, he discovered over 4,000 asteroids, including Apollo asteroids, Amor asteroids, as well as dozens of Trojan asteroids. Gehrels also discovered a number of comets. In an interview, Gehrels was asked what he would do if an asteroid hit the Earth. He said, "Go out there and have a look, of course."