– January 29, 2020 – Science
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- New type of aurora borealis discovered in Finland shows the importance of citizen science
It’s not every day that a new type of polar aurora is discovered. And it is even less common for this aurora to provide a better understanding of a little-known layer of the Earth’s atmosphere. These “dunes” are therefore a fascinating scientific find.
In 2020, there is still room for scientific discoveries about physical phenomena that we thought we already knew well. And participatory science has a lot to do with it. In AGU Advances, a research article published on January 28, 2020 presents a completely new type of aurora borealis. They were discovered in Finland thanks to a professional astrophysicist supported by citizen scientists. These new auroras are nicknamed “dunes”.
Polar auroras are luminous phenomena generated by the solar winds, when their flow of charged particles interacts with the Earth’s ionosphere and its gases (oxygen, nitrogen). The resulting excitation of the molecules will cause the charged particles to “rain” into the upper atmosphere, resulting in a light reaction. The interaction of particles with nitrogen emits blue, red, violet; with oxygen, it emits red and green. We’re talking northern lights in the north, southern lights in the south.
The physical process at work behind the auroras is fascinating, complex, and a singularly different phenomenon lies behind each of them and each colour. This is what motivated the Finnish astrophysicist Minna Palmroth to write a book, in the form of a guide, to catalogue them and help understand them. For this book, she has referenced all the auroras she has observed with the cooperation of enthusiasts – amateur scientists. It was then that they jointly noticed that a certain type of aurora referenced did not fit into any identified category.
The investigation was able to begin and, by chance, these celestial dunes reappeared shortly after the book was published. The “citizen scientists” captured many images of the phenomenon and sent them to Palmroth. Thanks to this exceptional database, the astrophysicist was able to characterize the aurora borealis in greater detail. Not only are they a new category, but they also provide a more detailed view of the Earth’s upper atmosphere.
- Read: How to explain the existence of an “iron snow” in the heart of our planet?
The “dunes” take the form of undulating waves (as on a lagoon), horizontal, of a flamboyant green whose brightness fluctuates. The phenomenon is thought to be caused by variations in the density of oxygen in the mesosphere – a lower layer of the upper atmosphere, between 50 and 80 km above sea level. We must imagine that in this layer of the atmosphere there are some sort of “mascarets”: this is how we describe a sudden rising tide in a bay, a river, which is translated into a wave in the water. But in the mesosphere, the process is equivalent but with oxygen atoms that suddenly densify.
“In terms of physics, this would be an incredible discovery”
According to the research paper, these aurora borealis in the form of dunes would come from these oxygen fluctuations in the mesosphere. An idea that is important because this layer of our planet is little known, so much so that it is sometimes nicknamed “ignorosphere”: it is difficult to study because it is too far from space satellites and too far from terrestrial radars and balloons. If these auroras are confirmed as a product of this “ignorosphere”, then they could become a valuable tool for study.
“In terms of physics, this would be an incredible discovery, as it would represent a new and never before observed mechanism of the interaction between the ionosphere and the atmosphere,” says Palmroth. The astrophysicist also believes that the discovery of these dunes is proof of the importance of participatory science, and that it can “create a general interest in physics, showing how citizens can take part in science by helping to discover new phenomena“.
- Read: Why the Northern Lights are asymmetrical between the North and South Poles