The illuminated “sand dunes” are a rare type of northern lights

On January 20, 2016, amateur photographers recorded luminous green waves in the northern European night sky. Finnish scientists have studied their recordings and have now concluded that the “luminous sand dune” is a previously unknown type of northern lights.

Aurora is created when charged particles from the sun enter Earth’s atmosphere. Earth’s magnetic field deflects particles toward the poles. When the oxygen and nitrogen atoms collide there, their energy is released in the form of colored light. Although the Northern Lights look messy and unique, there are still variations of the Circus Lights. Most of these are well documented. Rarely, new types of aurora borealis are discovered.

Until now. In 2016, hobbyist scientists around the world called for providing them with pictures and videos of green sand dunes, so that they could link them with satellite data. Thus they confirmed their suspicions: It is an extremely rare new form of aurora borealis.

Undulating dunes occur only in the upper parts of the atmosphere, and are a layer in the atmosphere that is too low to be explored by satellites (about 100 km above the surface of the Earth). The light sight is caused by an increase in the density of oxygen atoms at this height in the atmosphere. These differences cause brightness within the dune waves, which can be up to 45 kilometers long.

Source: University of Helsinki, Finland