Next time you’re waiting for the Aurora Borealis or Northern Lights to arrive – perhaps in Alaska, northern Canada, Iceland, northern Norway, Finland or Sweden – look for “Auroral Beads” because something special is about to happen.
NASA’s fleet of THEMIS spacecraft has helped uncover the truth about a very special type of aurora, also known as the “Northern Lights” in the Northern Hemisphere.
Described as “like a shining pearl necklace”, the phenomenon of “auroral beads” can sometimes be seen before large auroral displays, but so far the scientists are puzzled.
What are the auroras?
Aurora is a natural sky phenomenon that appears near the Arctic Circle (Aurora Borealis or Northern Lights) and the Antarctic Circle (Aurora Australia or Southern Lights).
They are caused by charged particles from the Sun and are accelerated by the Earth’s magnetosphere to interact with atoms in the upper atmosphere.
What are ‘Auroral Beads’?
They are pearls which according to scientists are seen illuminating the sky as single pearls in the shining “pearl necklace”.
They usually appear as the aurora begin to glow, so being a mystery in its own right, it is thought that they may cause or hint at the aurora’s impressive performances.
For what reason ‘beads of pearl’?
They are caused by plasma disturbance in the space around the Earth, and not in the Earth’s upper atmosphere, as previously suspected.
“We now know for certain that the formation of these beads is part of a process that precedes the triggering of an alternative in space,” said THEMIS chief investigator Vasilis Angelopoulos at the University of California, Los Angeles. “This is an important new piece of the puzzle.”
As the plasma emitted by the Sun interacts with the Earth’s magnetic field, it creates sharp bubbles of plasma behind the Earth. Comparing this to a lava lamp, they point out that the imbalance in buoyancy between bubbles and heavy plasma in the magnetosphere creates 2,500 miles wide plasma fingers that pull towards the Earth.
This is why “auroral pearl.” The results were published today in Geophysical Research Letters and Journal of Geophysical Research: Space Physics.
What is NASA’s THEMIS mission?
It is a fleet of three spacecraft orbiting the Earth. Since its launch in 2007, THEMIS has been taking detailed measurements as it passes through the magnetosphere enabling scientists to understand the causes of the submersions that gave rise to the auroras.
By modeling the atmosphere near Earth at scales 1.2 million miles to tens of miles, THEMIS scientists were able to show details of how aronal beads are produced.
Karim Sorathia said, “There are very dynamic, very small-scale structures that people see in Aurora that are difficult to connect to the big picture in space because they happen very quickly and on a very small scale.” New papers and scientists NASA’s Center for Geospace Storms is headquartered in the Johns Hopkins Applied Physics Laboratory. “Now that we can use global models, to mark and examine them, which opens up a lot of new doors.”
You want clear skies and wide eyes.