A visitor from deep space paid a brief visit to Earth yesterday, snapping pictures and then flying off for a landing on a distant comet. The visitor was the European Space Agency's Rosetta spacecraft.

Launched in March 2004, Rosetta was programmed to fly to a comet named 67P/Churyumov-Gerasimenko, arriving in 2014. There, it will land - the first spacecraft ever to make a controlled landing on a comet.

Getting to the comet, however, will require a series of planetary flybys to pick up a gravitational speed boost, including two swings past the Earth, and one past Mars.

On Tuesday, Rosetta zipped by our home planet, and scientists used the opportunity to switch on Rosetta's navigation camera and take some pictures. They show Earth and the moon as a visitor from outer space might see them. Looks pretty barren. Not much chance for life there, right? 

Or maybe there is. Here are some Rosetta shots of the nightside of the planet, city lights blazing. Who left the porch light on?

And finally, here is a pair of images taken through a telescope on the ground as Rosetta sped by. One shows the spacecraft as a faint streak across the starry background. The other tracked Rosetta, which appears as a white dot, while the stars are streaked by the long exposure.