A student at Lowell Observatory began teaching her astronomy. Then she began work as a field assistant for her husband, working on his search program mapping and analyzing impact craters. Carolyn Shoemaker started her astronomical career in 1980, at age 51, searching for Earth-crossing asteroids and comets at California Institute of Technology, Pasadena, California, and the Palomar Observatory, San Diego, California. That year, Shoemaker was hired at the United States Geological Survey (USGS) as a visiting scientist in the astronomy branch, and then in 1989 began work as an astronomy research professor at Northern Arizona University. She concentrated her work on searching for comets and planet-crossing asteroids. Teamed with astronomer David H. Levy, the Shoemakers identified Shoemaker-Levy 9, a fragmented comet orbiting the planet Jupiter on March 24, 1993.