New kind of northern lights called ‘dunes’ discovered by amateur scientists

Phenomenon arises from largely ignored part of Earth's atmosphere

Amateur astronomers have helped discover a new kind of northern lights, known as "dunes".

Citizen scientists teamed up with space researchers to find the "new auroral form", which consists of spectacular glowing waves.

The "dunes" are thought to be created when particles released by the sun cause oxygen atoms in our atmosphere to light up and glow.

In a newly published study, researchers tracked down the origin of the dunes to the Earth's upper atmosphere.

The sun pushes out a flow of charged particles, which are known as solar winds. When they arrive at the Earth's ionosphere, they excite the oxygen and nitrogen atoms found in the upper atmosphere, and that energy is released as lights.

While the northern lights are often seen as one phenomenon, they are something like clouds: there are a whole host of different kinds, each of which are formed in their own particular ways.

The new discovery began when the University of Helsinki's Minna Palmroth looked to collect these different kinds of northern lights, in collaboration with enthusiasts. Those hobbyists took photographs of thousands of different examples of the northern lights, which she picked through and categorised for a book to guide those watching the aurora borealis.

But as the hobbyists collected those images through Facebook, they found that many of them included a kind of auroral form that was not part of the existing classification. Those were set aside to be examined later, and the book was published.

Just days after it came out, enthusiasts spotted the mysterious form again: they saw a green-tinged, even set of waves that looked similar to dunes on a sandy beach. They told Professor Palmroth, who was able to get to work looking into it.

"One of the most memorable moments of our research collaboration was when the phenomenon appeared at that specific time and we were able to examine it in real time", says Northern Lights and astronomy hobbyist Matti Helin in a statement.

The hobbyists and space researchers worked together to collate photos from across Finland. Combining the images – and looking for clues such as stars in the background – allowed the scientists to discover where exactly the lights were coming from.

They noted that the glowing dunes appeared relatively low down, just 100 kilometres up. Their waveform stretched 45 kilometres across.

That height put them in a particularly neglected part of the sky: it is where the Earth's atmosphere collides with the edge of space, and is difficult for satellites to see.

"Due to the difficulties in measuring the atmospheric phenomena occurring between 80 and 120 kilometres in altitude, we sometimes call this area 'the ignorosphere'," she said in a statement.

The phenomenon appears to happen because of the "bore" phenomenon. Scientists say that gravity waves are born in the atmosphere and then rise up – but when they hit a particular layer, they can be bent and stretch out for long distances.