A blast from the past. This article and interview first appeared in Astronomy and Space magazine in June 2007.
The early Solar System was a violent place. One theory states that shortly after Earth’s formation four and a half billion years ago, a body the size of Mars thumped into Earth, blasting off massive amounts of debris. This debris eventually coalesced to form the Moon. After formation, the Moon underwent a period of intensive bombardment by meteorites that scared, fractured and left the Moon covered in craters of all sizes. This period was known as the late heavy bombardment and occurred between 4.1 and 3.8 billion years ago.