It's how aliens would see Earth — if their telescopes were powerful enough.
A NASA space probe has captured stunningly detailed video footage of the Moon passing in front of the Earth from a distance of 31 million miles, more than 100 times the Moon's orbit.
"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," explained University of Maryland astronomer Michael A'Hearn in a NASA press release.
NASA's Deep Impact spacecraft, on its way from one comet rendezvous to another, was instructed to snap stills of our home planet in 15-minute intervals on May 29.
The colors are not exactly what we're used to seeing in images of the Earth and Moon — for example, the Moon is more brown than white.
That's because the photos were taken using the near-infrared part of the light spectrum, which "sees" vegetation more easily, then shifted "up" to visible light.
From the images, scientists can learn what to look for in the search for Earth-like planets around other stars. There's a noticeable gleam as sunlight reflects off the oceans, and similar patterns of light might indicate vast seas on alien worlds.
Still, our ability to see extrasolar planets, the closest of which would be at least 26 trillion miles away, in such detail is far beyond the means of existing telescopes, and possibly those of intergalactic astronomers as well.
"An alien civilization would need technology far beyond what Earthlings can even dream of building," Sara Seager, a planetary theorist at MIT, said in the NASA press release.