Named the auroral dunes, the phenomenon was discovered by citizen scientists in Finland; it occurs at a relatively low altitude of 100 km (62 miles), in the upper parts of the Earth’s mesosphere, and is believed to be caused by waves of oxygen atoms glowing due to a stream of particles released from the Sun. The auroral dunes appear as a green-tinged and even pattern of waves resembling a striped veil of clouds or dunes on a sandy beach. Image credit:...
