When the magnetic field lines curve symmetrically around Earth, aurorae should appear in identical places in the Northern and Southern hemispheres. And, if you could view both light displays simultaneously, they would look pretty much the same.
Scientists thought the reconnections displaced one aurora relative to the other. The team studied images captured by spacecraft for 10 pairs of aurorae that occurred simultaneously in the Northern and Southern hemispheres between and The aurorae started out at asymmetric locations on the globe.
For example, on November 15, , the southern lights aurora australis flashed west of the northern lights aurora borealis.
But as the light displays proceeded, their positions shifted, becoming more symmetric. The shifts coincided with substorms. Breaking of the field lines—which they observe happens when the substorms hit—releases the magnetic pressure that built up from the squeezing and removes the skew. The intense solar radiation bursts that occur during aurorae and substorms can harm astronauts in space and alter the paths of orbiting satellites.
They can also interfere with GPS positioning as well as power grids and other technological systems. Scientists cannot accurately predict where and when space weather will hit, Mueller-Wodarg says. But they have at least solved one shining mystery in the night sky. Instead, the new research finds it is differences in pressure being exerted on the magnetotail that cause these auroral differences. The magnetotail is being constantly squeezed by the solar wind and IMF, and it is this non-uniform squeezing on it from different directions that is causing the differences in auroral displays at the two poles.
The squeezing depends on the orientation of the IMF. Skip to content Skip to navigation. Search Search Close Search. For Experts How to use Scimex Working with the media. Why do the aurora lights in the north and south pole look different? Embargoed until: Publicly released: Researching the interactions of these phenomena have debunked previous theories around why the lights can have different shapes and can occur in different locations.
This research also helps scientists to better understand the interactions between the sun and earth, which could help with predicting space weather. They can make a much wider auroral ring, or cause a large bulge on the night side, so that people in more populated areas nearer the equator may see an aurora every few years or once a decade.
More energetic solar particles mean a larger auroral ring that can be seen at lower latitudes. So when there is unusually high activity on the Sun, the region of auroral activity on Earth becomes wider, and there is a chance of seeing auroras at lower latitudes, where most people live.
Where migh t you be able to see auroras on a night like this? This picture shows the north auroral oval during a major geomagnetic substorm on July 15, , when the Sun was nearing the maximum in its year activity cycle. Can you tell where the biggest auroras are? Look carefully, and you'll notice that Greenland and the top of North America are completely inside the oval. Here is beautiful aurora picture from Ontario, in eastern Canada.
It was taken during another substorm, just a few days earlier. This is on roughly the same latitude as New England in the United States. And this picture, even more recent, comes from Mount Wilson observatory in southern California during the arrival of a major geomagnetic substorm on March 31st, If you would like to see today's auroral forecast, visit the University of Alaska's Geophysical Institute. See if there are any auroras near you!
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