Varying crater rate

Varying crater rate

. The rate of forming craters on the lunar surface is plotted against time. The arrows point to the crater rate and rock ages at various Apollo landing sites. The crater rate was very high during an intense bombardment that occurred 3.9 billion years ago. The rate dropped rapidly during the subsequent billion years, giving way to the lower steady rate of crater production that has persisted for the last 3 billion years. With such a curve, we can obtain approximate surface ages just by counting the number of craters in different parts of the Moon. Recent data have provided evidence of an increase in the cratering rate over the last 400 million years.

Copyright 2010, Professor Kenneth R. Lang, Tufts University