Aurora australis, the southern version of the phenomenon as seen by the International Space Station in 2010.
Auroras draws the sky around the poles when the sun is particularly active, throwing highly charged particles into the atmosphere of the Earth. Scientists once believed that magnificent events were mirror images, but to their surprise displays in the north (polar glow) and in the south (aurora australis) do not match exactly.
Since scientists have realized that these two skyscreens are not aligned, they are trying to figure out why. Now a team of researchers thinks it has found the cause – asymmetry in the magnetic queue of the Earth. But what's stranger is that asymmetry is caused by the exact opposite of what scientists expected.
"The reason for this is exciting that we previously thought that the asymmetry in the system enters the magnetosphere by a mechanism called re-linking the tail," said Anders Oma, a PhD student at the University of Bergen, Norway, and lead author of the new study. says a statement published by the magazine. "What this book shows is that it may actually be the opposite." [Northern Lights Photos: The Amazing Auroras on Earth]
Everything comes down to the magnetic queue of the Earth, which is created by interactions between our planet and the sun. These interactions begin with the Earth's magnetic field, which scientists regard as springs from the guts that rotate through the core of the Earth and create an electric charge. Magnetic fields – from fridges to planets – create invisible magnetic field lines between the North and South poles that can control the behavior of the material around them.
But the Earth's magnetic field is not the only one there – the sun also has one that affects the constant flow of highly charged plasma particles that flow in every direction. The magnetic field embedded in this stream, called the solar wind, interferes with the Earth's production, crosses it on the Earth's face facing the sun and stretches it on the night side, turned back from the sun, into a tail.
The lines of the magnetic field pass through the distorted field and are not fixed in place – they break and reform into dramatic events called repeated links. This phenomenon in the tail is what scientists have thought to cause a mismatch between the northern and southern shades. (This is the tail that matters to the radiance because it is the side of the magnetic field that is in the dark, and the brightness is visible only at night.)
Instead, the team behind this study realizes that the magnetic field of the solar wind is not always aligned exactly with Earth's. When it is distorted, it introduces asymmetry between the North and South Pole into the magnetic field of the Earth – and this in turn causes a mismatch between the northern and the southern radiance.
So the researchers collected simultaneous far infrared observations of the north and south lights and traced how close the two aurors were. Then they added data about the re-connections in Earth's magnetic queue. But when they compared the two sets of measurements, they saw exactly the opposite of what they expected to see – instead of these dramatic restorations, increasing the asymmetry of the glow, they pressed the glow back to coincidence.
Understanding the luminosity itself is not vital, as the shades are just symptoms of how the sun is affecting the Earth through a set of phenomena called cosmic times. But cosmic weather can hinder navigation and communication satellites and even turn off electrical networks. And scientists are still trying to understand how cosmic time really works and how they can better predict it. Aurors are just the most beautiful phenomenon to start cracking.
The study is described in an article published last month in the Journal of Geophysical Research: Space Physics.