At the moment, scientists know a lot about what causes the Aurora, how it forms, what colors it can have, they know how to forecast the Northern Lights, and many, many other interesting and useful things about this beautiful phenomenon. But there are still a few questions which scientists are trying to answer.
One of these questions found an answer very recently (on June 7, 2021), thanks to the work of physicists from UCLA, Wheaton College, the University of Iowa and the Space Science Institute!
What is the Aurora?
The temperature in the Sun’s core is huge (like millions of degrees Celsius). At this temperature, a nuclear fusion reaction of hydrogen occurs. As a result, electrically charged particles (electrons and protons) are thrown out from the Sun’s atmosphere and they escape into space and, at some point, they reach Earth and they interact with Earth’s magnetic field (called magnetosphere), creating a so-called disturbance in the magnetosphere. The electrons from the solar wind then accelerate along the magnetic field lines and then collide with the gases that make up Earth’s atmosphere (mostly oxygen and nitrogen). These collisions determine the emission of visible light. It is this visible light what we call the Aurora Borealis or the Northern Lights.
The mystery – until a few days ago – was that it was not well understood how the acceleration of electrons along the magnetic field lines occurs.
But the mystery is now solved! After creating, with the help of special scientific equipment, the same conditions just like those in Earth’s magnetosphere, the research team concluded that the acceleration happens due to the fact that the electrons “surf” along the electric field of a wave (in this case a so-called Alfvén wave, see what this is below), which transfers the energy of the wave to the accelerated particles, through a process called Landau damping.
Put it simply and without fancy words, as one of the researchers that took part in this study said, “measurements revealed (that the) electrons undergo (…) acceleration by the Alfvén wave’s electric field, similar to a surfer catching a wave and being continually accelerated as the surfer moves along with the wave”.
Alfvén waves are launched along the magnetic field lines, towards our planet, at the moment of magnetic reconnection, which is a violent process when two magnetic field lines couple together (which happens during a geomagnetic storm for example). Electrons from the solar wind, which are ‘trapped’ in the magnetic field line, “surf” along the field line, being accelerated by this Alfvén wave.
The science behind the Aurora
In this article is presented only a very small part of the Aurora science.
Now you have the chance to completely understand this magnificent phenomenon, starting from beginner level! I designed for Aurora Labs the Learn the Aurora workshop (either the online version, or the workshop we can do together here in Vadsø) where you can learn, through simple experiments and explanations (suitable even for the non-scientists!), the complete science behind the Northern Lights!
So, be sure to take part in my online workshop now, during summer, and be prepared to see (and understand) this beautiful phenomenon next winter!
…Oh, and did you know Aurora Labs can even certify you as an expert in Northern Lights? 😉