It is a view that has never been glimpsed by human eyes.

A second-hand NASA space probe has shot an extraordinary movie showing the moon passing in front of a rotating Earth.

The time-lapse video was recorded in May from 50 million kilometres out in space - about 125 times further away than the moon is from Earth.

Named Deep Impact when it was launched in January 2005, the probe's original mission was completed on July 4 that year when it sent a 370 kilogram "impactor" slamming into a comet called Tempel 1.

The 10-kilometre-a-second crash blasted part of the comet's surface into space, allowing scientists to study the chemical composition of its interior.

Deep Impact, still working well, was later given two new missions.

It was redirected to pass another comet, Hartley 2, on November 4 2010.

On its way to Hartley 2, the probe will use its instruments to search for planets circling stars beyond our solar system.

Aiming its cameras at Earth, the probe snapped pictures every 15 minutes, producing a movie showing the rotating Earth, with its clouds and continents, including Australia, clearly visible.

Then the orbiting moon passes into view, "transiting" across the face of our world.

Scientists hope it will provide them with vital clues in their hunt for life outside our solar system.

"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 Ahearn, a leading scientist on the probe's new mission.

Another scientist, Drake Deming, frrom NASA's Goddard Space Flight Center in Maryland, noted how a glint could be seen in the movie - caused by sunlight reflecting off the sea.

"Similar glints to be observed from extrasolar planets could indicate alien oceans," he said.

Two videos were made - one using a red-green-blue filter and another using a infrared-green-blue filter.

Using infrared light, said Deming, "makes the land masses much more visible because plants reflect more strongly in the near-infrared".

This suggests images recorded in similar wave lengths could be used in the future to spot vegetation on other worlds.

Deep Impact's new double assignment has led NASA to rename the craft EPOXI - a combination of Extrasolar Planet Observations and Characterisation and Deep Impact eXtended Investigation.

Timelapse of Deep Impact probe filming the Earth: [link]

Infrared timelapse of Earth: [link]