Star Trails Above, City Trails Below
NASA astronaut Don Pettit shot this beautiful long exposure photograph showing star trails and city trails from the International Space Station. The image was created by combining 18 separate long-exposure photographs.
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.
See those blue blotches that appear in a line on the face of our planet? Those are lightning flashes.
Image credit: Photograph by Don Pettit/NASA
