This was
your sky.

Rainbow Airglow over the Azores

The sky glows with repeating rainbow patterns due to airglow, which is always present but usually too faint to see. Disturbances in Earth's atmosphere, like an approaching storm, can cause these gravity waves to ripple. This long-exposure image, taken over the Azores, makes the undulating structure particularly visible. Airglow occurs when atoms and molecules in the upper atmosphere are excited by sunlight and then release that energy as light.