Why is the sun's atmosphere hotter than its surface? Maybe it's those huge plasma tornadoes.
Scientists may have an answer to one of the sun's greatest mysteries: Why is the sun's atmosphere some 300 times hotter than its surface?
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"Based on the detected events, we estimate that at least 11,000 swirls are present on the sun at all times," Wedemeyer-Böhm said.Skip to next paragraph
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Towering solar twisters
Although the twisters are enormous by Earth's scale, they are tiny on the surface of the sun. They were first detected in 2008 by Wedemeyer-Böhm and another researcher, but it wasn't until images of super-tornadoes were compared with those from the corona and photosphere that scientists realized how high the writhing gas extended — or the influence they could have on the sun's temperature.
The surface temperature of the sun is 9,980 Fahrenheit (5,526 degrees Celsius or about 5,800 Kelvin), while the corona peaks at 3.5 million Fahrenheit (2 million degrees Celsius or nearly 2 million Kelvin), a fact that seems counterintuitive.
After observing the sun, the international team created computer models in an attempt to determine how much energy — and thus heat — could be effectively transported by the twisters. They concluded that solar tornadoes could help to explain how the outer layer stays so hot, although Wedemeyer-Böhm notes that it is likely only one of a number of different processes powering the temperature of the sun's corona.
"The magnetic tornadoes offer a potential, alternative and widespread way to transport energy from the solar surface into the corona," Wedemeyer-Böhm said.
The tornadoes differ from those spotted earlier this year. Those much larger events were formed by twisting solar prominences, and were likely connected to mass ejected from the sun. The smaller tornadoes are more abundant, and make a more significant contribution to the corona's temperature.
The research was published in today's (June 27) issue of the journal Nature.