Written in the Sky: Aurora borealis uncovered
Dr Jim Wild, Department of Physics, University of Lancaster
The northern lights, or aurora borealis, have fascinated people for generations. Some believe the ghostly aurora lights in the night sky are the souls of the dead sending messages to the living. For space plasma physicist Jim Wild, the messages sent by aurora lights are vital. They are messages from the sun and we need to listen carefully.
Jim wants to be the first to unlock the secrets of the northern lights. He knows the strength of the nightly display is a mirror for solar activity and intense activity on the sun’s surface can trigger geomagnetic storms in the earth’s atmosphere. These storms can disrupt our communication systems, interfere with navigation and even wipe out power grids. So a geomagnetic tsunami has the potential to be devastating.
We follow Jim as he seeks out the aurora for himself. Because the earth’s magnetic force field only guides particles down near the north and south poles, Jim has to travel north to track the aurora borealis in Iceland. He searches for the unusual combination of a remote place that’s far away from the light pollution of any towns but also has access to both power and the internet.
Jim’s journey takes him to a dark and remote field the northern tip of the Scandinavian country, where he sets up a box of cameras and computer equipment, allowing him to record the whole night’s auroral borealis activity over Iceland. As it grows dark, he must assess the cloud coverage and decide whether he will see the lights. Some nights, he has to give up and go to bed. And, in a cat and mouse game with the prevailing cloud cover, he also moves between different field sites trying to catch a prolonged exposure to the aurora lights.
But a night with a good show is worth all of the effort and provides invaluable data. Jim records such nights using a fisheye lens by taking pictures of the magnificently lit sky every couple of seconds. He then stitches together each image taken throughout the entire night and plays it through in fast forward, allowing him to assess a whole night of the aurora borealis above Iceland in a matter of seconds.
“The excitement is figuring out the science behind the magic,” he reflects. “But it’s not like when you figure out a magic trick it suddenly seems less impressive. Looking at the aurora, it’s more magical.
“The aurora are mysterious in lots of ways. Scientists, for a very long time, couldn’t work out where the electrons that hit the upper atmosphere come from,” he says. “Strangely, this great night time show is caused by the sun. Electrically charged particles pour off the sun and stream past out planet. And some of the particles get trapped by the earth’s magnetic field.
“So the stronger the wind blows, the better the aurora. This link to the sun means that the aurora are a great barometer of solar activity and what’s going on in space around us.”
Written in the Sky by The Institute of Physics as part of the National HE STEM Programme is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
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