People have been observing the aurorae for millennia, and aiming scientific instruments at them for decades to try to understand them better, so you'd think by now we'd know about every kind of aurora there is.
Except nope. A new kind has just been discovered, and it was found due to observations by aurora chasers, people who brave the cold high latitudes to photograph the "northern lights"!
An aurora occurs when subatomic particles from the Sun slam into the Earth's (or any planet's) atmosphere. The particles are moving extremely rapidly, and when they hit an atom or molecule in the upper atmosphere they ionize it, blasting off an electron or two. When the electron recombines with its parent atom, it emits light at a fairly specific wavelength, or color. That color depends on the atom involved; the common green color seen in aurorae is from oxygen, for example. Red can be from oxygen atoms as well, and also from molecules of nitrogen.
A new type of aurora, called “the dunes”, can be seen as parallel ripples stretching to the left in this photo taken in Ruovesi, Finland in 2018. Credit: Rami Valonen
Charged particles like electrons or protons are affected ...