Image description: This photo of star trails was taken by Expedition 31 Flight Engineer Don Pettit on the International Space Station.
Pettit used the following photographic techniques to create 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.”
Photo from NASA JSC Photos.