If you want a front-row seat of how the Moon looks as it passes in front of the Earth...well, look no more.

NASA's Deep Impact spacecraft has relayed back to Earth a video of this space scenic event - a video that also helps scientists to develop techniques to study alien worlds.

The NASA Deep Impact spacecraft is the first to show a transit of Earth with enough detail to see large craters on the Moon, as well as oceans and continents on Earth.

Therefore, the video is a good primer on how to detect vegetated land masses on far-away, extrasolar planets. That is, the video sharpens our thinking about how to look for variations in the intensity of vegetated land masses in the near-infrared as an extrasolar planet rotates.

By the way, look for a "sun glint" in the movie, caused by light reflected from Earth's oceans. Similar glints gleaned in the future as spacecraft look for extrasolar planets orbiting their home star could indicate alien oceans!

It's important to remember that Deep Impact already made history: On July 4, 2005, the Ball Aerospace-built spacecraft unleashed an impactor that smashed into comet Tempel 1. Following that "worlds in collision" event, NASA decided to extend the mission to strive for a flyby of comet Hartley 2 in early November 2010.

That extended mission is called Epoxi - a name created from the melding of the two extended mission components - a search for extra-solar planets and the flyby of comet Hartley 2.

To get Epoxi, think Extrasolar Planet Observations and Characterization, or EPOCh and the comet flyby that's tagged as Deep Impact eXtended Investigation, or DIXI for short. Go figure!

This new video of Earth and the Moon was made by the Deep Impact spacecraft en route to its distant flyby of comet Hartley 2 - some two years from now.

So...long winded way for you to take a look yourself at the impressive video of the Moon transiting the Earth by going to:

http://www.nasa.gov/mov/260503main_red_green_blue2.mov

-- Leonard David