This was
your sky.

Aurora Over Clouds

Aurorae usually occur high above the clouds. The auroral glow is created when fast-moving charged particles from Earth's magnetosphere impact air molecules high in the atmosphere. An oxygen molecule, for example, will emit a green light when reacquiring an electron lost during a collision. The lowest part of an aurora typically occurs at 100 kilometers and up, while most clouds usually exist only below about 10 kilometers. This photo shows the relative heights of clouds and auroras.