As the ISS circles Earth at roughly 17,000 miles per hour, Flight Engineer Don Pettit takes 30-second exposures with a stock digital camera, then stacks those exposures into single frames that capture 10-15 minutes on the ISS. The rotation is fast enough for long exposures to blur the earth into gilded landing strip beneath a steady rain of stars–a scene I would have never imagined as beautiful before today. Heck, it’s a scene I would have never even imagined before today.
Expedition 31 Flight Engineer Don Pettit relayed some information about photographic techniques used to achieve the 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, then ‘stack’ them using imaging software, thus producing the longer exposure.”
Click the pic to see the set.