I learned about these photos from The Smithsonian’s post, Stunning Star Trail Photographs from International Space Station:
NASA astronaut Don Pettit recently uploaded a gallery of photos to the Johnson Space Center’s Flickr page. Pettit on how he captured these amazing images:
“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. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, the ‘stack’ them using imaging software, thus producing the longer exposure.”
I’m adding them to The Best Images Taken In Space.