Earth's Ionosphere

There’s a strange glow in the night sky, and it’s coming from a dynamic layer of the atmosphere at the boundary between Earth and space—what scientists call the ionosphere. The layer extends from about 50 to 360 miles above the planet’s surface, and swells in response to incoming solar radiation. The sun’s powerful rays energize particles in this region, causing them to emit light and kick out an electron, resulting in a cloud of charged particles. The colorful emission, known as airglow, is subtle and appears faint to the naked eye. But in long-exposure photographs taken from space, the vibrant red and green hues show up as distinct bands that curve across the Earth’s limb. In 2017, NASA will launch the Ionospheric Connection Explorer (ICON) mission to study what causes variation in airglow and how the combined effects of terrestrial weather and space weather influence the ionosphere. Watch the video to see footage of airglow captured from Earth orbit.