This was
your sky.

Rainbow Airglow over the Azores

Airglow, a phenomenon where Earth's atmosphere naturally glows, creates this giant, repeating rainbow over the Azores. Usually hard to see, airglow becomes noticeable when disturbances like approaching storms cause ripples in the atmosphere. These gravity waves are analogous to those created by a rock thrown into water. A long exposure makes the undulating structure particularly visible.