18 July 2008
NASA's Deep Impact spacecraft has made a movie of the moon passing in front of the Earth from the probe's vantage point millions of miles away.
Astronomers plan to use the video to develop techniques to look for Earth-like worlds in other solar systems.
"Making a video of Earth from so far away helps the search for other life-bearing planets in the universe by giving insights into how a distant, Earth-like alien world would appear to us," said Michael A'Hearn of the University of Maryland and the principal investigator for the Deep Impact extended mission.
Deep Impact, which sent an impactor into comet Tempel 1 on July 4, 2005, is currently 31 million miles away from Earth on its way to a flyby of comet Hartley 2 on Nov. 4, 2010.
During its cruise to Hartley 2, Deep Impact will be searching for extrasolar planets.
What would Earth look like to alien astronomers? See Video!