Watch an animation of the night side of Earth for one rotation of our planet. Earth's night twinkles with light, and the first thing to stand out is the cities.
Airglow is light that originates in the high atmosphere, associated with photochemical reactions of gases caused by solar radiation. Thank you Kristal Leonard-Ferrara!
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. She and her husband live in Tennessee, where they enjoy guitar playing and singing. They have 2 grown sons.