A scientist aboard the International Space Station took extraordinary photos of the starscape from aboard the vessel, using a special technique that highlights their movement.
Expedition 31 Flight Engineer Don Pettit used long exposures in conjunction with digital editing to achieve the star-trail effect.
Given that some of the shots required nearly 15 minutes of exposure, Pettit needed the software to overcome the limitations of his camera.
[W]ith modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image, Pettit explained.
To achieve the longer exposures, I do what many amateur astronomers do. I take multiple 30-second exposures, then 'stack' them using imaging software, thus producing the longer exposure.
The gallery was posted via the Johnson Space Center's Flickr account.