Formation and evolution of the Solar System formation of the Solar System. This period of heavy bombardment lasted several hundred million years and is evident in the cratering still visible on geologically dead bodies of the inner Solar System such as the Moon and Mercury. The oldest known evidence for life on Earth dates to 3.8 billion years ago—almost immediately after the end of the Late Heavy Bombardment. Impacts are thought to be a regular (if currently infrequent) part of the evolution of the Solar System. That they continue to happen is evidenced by the collision of Comet Shoemaker–Levy 9 with Jupiter in 1994, the 2009 Jupiter
Carolyn S. Shoemaker Carolyn S. Shoemaker Carolyn Jean Spellmann Shoemaker (born June 24, 1929) is an American astronomer and is a co-discoverer of Comet Shoemaker–Levy 9. She once held the record for most comets discovered by an individual. Carolyn Jean Spellmann was born in Gallup, New Mexico, United States. to Leonard and Hazel Arthur Spellmann. Her family moved to Chico, California, where she and her brother Richard grew up. Carolyn Spellmann earned bachelor's and master's degrees in history, political science, and English literature from Chico State University. Richard went to the California Institute of Technology (Caltech), where he earned a bachelor's degree in