Streaks of psychedelic colors show the passage of cities below the International Space Station (ISS), airglow in Earth’s atmosphere and the circling motion of stars in this stunning new image from Expedition 31 Flight Engineer Don Pettit.
Pettit created the image by combining 18 long-exposure digital images taken with a camera mounted inside the ISS on March 16, 2012. Because of the limitations of digital imaging sensors, multiple exposures are needed to get such an image.
“My star trail images are made by taking a time exposure of about 10 to 15 minutes,” said Pettit. “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.”
The bright blotches lined up at the lower portion of the image are lightning flashes within storm clouds.