This is a composite of a series of
images photographed from a mounted camera on the Earth-orbiting International
Space Station, from approximately 240 miles above Earth. Expedition 31 Flight
Engineer Don Pettit said of the 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." A total of 18
images photographed by the astronaut-monitored stationary camera were combined
to create this composite.
Image Credit: NASA
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