Night Lights From Space

An astronaut aboard the International Space Station took this image over the Red Sea on September 22, 2015. Taken at night, it reveals city lights in northeast Africa and the Middle East. Many people live along the Nile River. The glowing red and green lines along the Earth’s limb are an optical phenomenon called airglow. The color is the result of chemical reactions in the atmosphere. Besides red and green, airglow can also be blue.