Just when you think you might know all there is to know about a natural phenomenon, nature once again finds a way to surprise you. Such is the case with a new aurora discovered by physicists led by the University of Iowa.
The aurora was spotted in a video that is nearly two decades old. The researchers identified a section of the diffuse aurora—the faint, background-like glow accompanying the more vivid light commonly associated with auroras—that goes dark and then suddenly reappears.
The researchers decided to call this new type of aurora “diffuse auroral erasers."
“The biggest thing about these erasers that we didn’t know before but know now is that they exist,” says Allison Jaynes, assistant professor in the Department of Physics and Astronomy at Iowa and study co-author. “It raises the question: Are these a common phenomenon that has been overlooked, or are they rare?
“Knowing they exist means there is a process that is creating them,” Jaynes continued, “and it may be a process that we haven’t started to look at yet because we never knew they were happening until now.”
Auroras occur when charged particles flowing from the sun come into contact with Earth’s magnetic bubble, escaping and falling toward our planet. It is the energy released during their interactions with gases in Earth’s atmosphere such as oxygen, nitrogen, and other molecules that generates the beautiful lights so commonly associated with auroras.
In this case, the phenomenon is not new (it was videotaped over 20 years ago) but it is newly-discovered. Just last August, the International Space Station captured an aurora meeting an airglow in what turned out to be a stunning image.
In more recent news, another new auroral phenomenon called dunes and discovered by Finnish researchers a year ago was found by University of Helsinki researchers to probably be caused by areas of increased oxygen atom density occurring in an atmospheric wave channel. The researchers noted that dunes are extremely rare. This begs the question: what other types of auroras can we discover if we insist on looking close enough?
The diffuse auroral eraser study was published in the Journal of Geophysical Research Space Physics.