Millions of visitors seek out the best view of an aurora each year. However, researchers are starting to look more closely at the colorful spectacle. Physicists suspect auroras could give key insights into the physics of space.
A new study revealed that auroras function as TV screens, showcasing what happened millions of miles away from Earth’s magnetic field. Often called the northern lights, auroras form when charged particles from the sun during a solar flare collide with the Earth’s magnetic shield. These collisions cause the electrons to move to a high energy state. The electrons release a photon (light) when they drop to a lower energy state, leading to the bursts of light that make up auroras.
Exploring an explosive aurora’s energy changes
The study was conducted by a team from the University College London in conjunction with the University of Reading. The teams remotely observed a changing aurora to explore the physics behind why, when and how energy is released as the aurora explosively changes.
"Somewhere in the huge volume of space into which Earth's magnetosphere stretches, this energy release occurs via instability which is really hard to pinpoint. They cause substorms whereby charged particles surf into the Earth's atmosphere on electromagnetic waves, releasing large amounts of energy and lighting up the aurora" said Jonathan Rae of UCL Space & Climate Physics. Rae was also one of the study’s authors.
"By studying auroras closely, we can map back to where in space the instabilities are occurring and study the physics that cause them. It's much more efficient than trying to observe vast areas of space."
To conduct their observations, the physicists scanned large swaths of the sky and pinpointed the aurora they wanted to cover -- Poker Flats in Alaska. They used data from the Multi-spectral Observatory Of Sensitive EM-CCDs (MOOSE) camera that tracked the 2012 Aurora event for four minutes.
While four minutes of data might not seem like a long time, the time was enough for scientists to get substantial data.
Analyzing the physics behind auroras
The teams then processed the data to look for clues to how the aurora formed. By comparing notes on that formation with the team’s theories, they could narrow down where the instability in space was that caused the aurora.
"We've shown that it's possible to only study aurora to find out where instabilities are in space, which has not been done before," explained co-author Colin Forsyth with UCL Space & Climate Physics.
"Our method allows us to predict what the instability is and where it is in space. In fact, the region we've identified is incredibly small in space terms -- only a small fraction of the volume of the Earth -- and we hope to study it in more detail using spacecraft that pass through the area."
Before this study, researchers could only describe the aurora and the events that described it. However, the new study marks the first time extensive physical analysis has been done about the physics behind the events.
"Importantly, our work has given scientists more physics to work with. A whole range of theoretical models can be tested and refined based on the physical characteristics we've captured," added co-author Clare Watt from the University of Reading.
"What we've reported has eluded scientists since auroras were first described in the 1960s and while we use Earth as our closest laboratory, the findings will apply to other events elsewhere in the solar system. We now look forward to pinpointing this epicenter in space and finding out what makes it unstable," concluded Rae.