Astronauts aboard the International Space Station (ISS) see the world at night on every orbit — that’s 16 times each crew day. An astronaut took this broad, short-lens photograph of Earth’s night lights while looking out over the remote reaches of the central equatorial Pacific Ocean. ISS was passing over the island nation of Kiribati at the time, about 2600 kilometers (1,600 miles) south of Hawaii.
Knowing the exact time and the location of the ISS, scientists were able to match the star field in the photo to charts describing which stars should have been visible at that moment. They identified the pattern of stars in the photo as our Milky Way galaxy (looking toward its center). The dark patches are dense dust clouds in an inner spiral arm of our galaxy; such clouds can block our view of stars toward the center.
The curvature of the Earth crosses the center of the image and is illuminated by a variety of airglow layers in orange, green, and red. Setting stars are visible even through the dense orange-green airglow.
The brightest light in the image is a lightning flash that illuminated a large mass of clouds. The flash reflected off the shiny solar arrays of the ISS and back to the camera. The dim equatorial cloud sheet is so extensive that it covers most of the sea surface in this view.
ISS, Orbit of the Earth
August 9, 2015
Image Credit: NASA
Explanation from: http://www.nasa.gov/image-feature/stargazing-from-the-international-space-station