NASA's Cassini probe has been snapping shots of Saturn and its moons for the better part of the last decade.
But today it's gearing up for a very special shot, not of the planet its orbiting or anything close by, but of its home planet, our own Earth.
Granted, the main target will still be Saturn and its entire ring system. But somewhere in there, you'll be able to spot a small white dot, our planet, 1,445 million km (898 million miles) away from the probe. At that distance, our planet will be a single pixel in the mosaic image.
The Cassini team wants to mark this occasion in a special way, by going outside and waving at the probe. The shots will be taken between 21:27 GMT and 21:42 GMT.
Most of the western hemisphere will be illuminated by the sun during that time, from Cassini's point of view. Of course, those details won't be visible in the photo.