Trailing stars: Mesmerizing photos from Earth orbit

Once Upon a Time in a Galaxy Far, Far Away – those are the first words that come to mind when looking at these breath-taking images taken from Earth's orbit.

The photos were made by NASA astronaut Don Pettit, some 380km above Earth, from the International Space Station.

“My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image,” the astronaut said on his blog.“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,” Pettit explained.The ISS makes one revolution every 90 minutes and as a result, long-exposure pictures taken from the station show star trails as circular arcs, with the centers of rotation being the poles of the ISS. A total of 46 images photographed by the astronaut-monitored stationary camera in the Cupola were combined to create the composites.Pettit is one of six astronauts currently living aboard the station. The crew includes NASA astronaut Joe Acaba, European astronaut Andre Kuipers, and Russian cosmonauts Oleg Kononenko, Gennady Padalka and Sergei Revin.