Taken by astronauts on the ISS as it passed over the Greek island of Kos, the light blue ribbons across the top of the image are polar mesospheric or ‘night-shining’ clouds, so-called because they are commonly spotted at twilight. But not in this case – this unusual shot was taken at midnight local time. The ISS was moving to the north east, nearly parallel to Earth’s terminator, which made it possible to observe the apparent “sunrise” that illuminated the clouds.
Polar mesospheric clouds typically occur at high latitudes of both hemispheres and high altitudes near the boundary between the mesosphere and thermosphere.
Image courtesy of NASA