Finnish hobby astronomers have discovered a new form of northern lights. A research team from the University of Helsinki has just announced this. Specifically, the novel pattern is aurora dunes that resemble sand wave patterns on a beach. The researchers around Minna Palmroth came across the new form after evaluating photos collected by amateur astronomers.
Northern lights are created when electrically charged particles of the solar wind hit the upper layers of the earth’s atmosphere. There they particularly stimulate oxygen and nitrogen molecules to glow. Such plays of light occur primarily in the polar regions. The solar wind is the stream of charged particles that constantly emanates from the sun in all directions. So far, four types of polar lights have occurred: these are corona, curtains, quiet arches and ribbons.
According to Palmroth, the new dune shape is created by “pinched” gravity waves in the mesosphere, the middle of the five layers of the earth’s atmosphere. Because the region of the upper mesosphere is rather turbulent, it is almost impossible to create such even layers of polar light there. The researchers associate the fact that the aurora dunes still occur with another phenomenon, the mesospheric surf.
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