Some areas of the Moon have more craters than others. The number of large versus small craters also varies across the surface. A census of the crater population can tell scientists the relative ages of different parts of the surface and reveal information about the make-up of the early solar system.
Such a census has been compiled from the elevation data being sent back by the LOLA instrument on Lunar Reconnaissance Orbiter. It comprises over 5000 craters larger than 20 kilometers in diameter. Some conclusions drawn from an analysis of this crater catalog by members of the LOLA team are described in the September 17, 2010 issue of the journal Science.
This animation illustrates the process of systematically counting craters. Craters larger than 20 kilometers in diameter light up to show color-coded elevation. Some areas, such as the maria and the Orientale basin, are notably sparse, implying that these areas are younger. The processes that formed them erased the record of older impacts visible elsewhere on the Moon.
Using the Lunar Reconnaissance Orbiter's Lunar Orbiter Laser Altimeter (LOLA), NASA scientists have created the first-ever comprehensive catalog of large craters on the moon. In this animation, lunar craters larger than 20km in diameter "light up" using LOLA elevation data. Craters light up in an east to west (Tranquillitatis toward Orientale) sweep around the Moon.