A NASA satellite has taken its three billionth image of the earth's atmosphere.

The CALIPSO satellite reached the milestone last week.

The satellite is tasked with providing insights into the role clouds and airborne particles play in regulating Earth's weather, climate and air quality.

The satellite uses light detection and ranging similar to radar that provides NASA with images showing the thickness and composition of clouds and aerosol layers and their altitudes.

In the past five years it has generated data that would fill about 75,000 CDs.

NASA's Langley Research Center in Hampton is leading the CALIPSO mission, which is providing information to scientists and researchers from more than 35 countries.

CALIPSO is a collaboration between NASA and the Centre National d'DEtudes Spatiales, the space agency of France.

©2011 The Associated Press. All rights reserved.