Here's how the Earth looks like from 31 million miles away. This clip was intended to shed light on how other Earth-like worlds would appear.
“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, Earthlike alien world would appear to us.”
The features that are most notable are the "sun-glint" caused by light reflected from Earth’s oceans. Similar glints to be observed from extrasolar planets could indicate the existence of alien oceans.
In infrared, land masses with vegetation are more apparent, because plants reflect more infrared light. Hence, infrared-imaging techniques could be used to observe extrasolar planets for signs of vegetation.
The video was captured by the Deep Impact Probe, whose extended mission now is called EPOXI (Extrasolar Planet Observation eXtended Investigation).
Alien’s-eye view of Earth