Friday, October 31, 2014

A Most Unusual Sunspot

A close-up of AR12192 takenon October 21, 2014 from Langkawi Nagtional Observatory, Malaysia. Image by Karzaman Ahmad and shared at

          From PBS Newshour reports on the current large sunspot--the largest in 24 years--which has spewed out an unusually large number of solar flares, but only one Coronal Mass Ejection (CME). The article first explains that because the mass of the sun does not rotate as one body, the magnetic fields running through the sun can get twisted as one part of the sun rotates past another. Eventually, the energy bound up in the twisted field lines must release themselves through solar flares or CMEs.

Releasing this pent-up energy typically takes two forms: a solar flare or a coronal mass ejection, and this is key to what makes the behavior here unusual. A coronal mass ejection is made up of balls of gas ejected from the sun’s outer atmosphere, consisting of charged particles and magnetic field. The fastest CME’s travel up to 93 million miles a day, or millions of miles per hour. A solar flare is a burst of x-rays and energy, typically smaller and shorter-lasting than a CME, and rather than being launched out into space, it is caused by material accelerated back into the sun. 
 This latest sunspot is producing lots of flares — really, really, big ones — but hardly any coronal mass ejections. (Though it did produce one single CME before it rotated into our field of view.) 
“I can’t remember ever seeing a sunspot producing so many solar flares and so few CME’s,” said Michael Hesse, director of NASA Goddard’s Heliophysics Science Division, the team that stares at the sun 24 hours a day. “It wants to get rid of this energy, but we don’t understand why it does it through a flare and not a CME.”
But it’s produced 10 major solar flares, Hesse said. Six of these were rated X-class, which is equivalent to 100,000 times the amount of energy produced by humans in one year. Also, a billion Hiroshima-sized nuclear weapons.
...  When a solar flare erupts, it lights up the side of the Earth that’s facing the flare, and heats up the Earth’s upper atmosphere, or ionosphere, which can temporarily change its properties. Solar flares pose less danger than CME’s, but they can affect short-wave radio communication used by pilots and ships, since the radio waves are bounced off the upper atmosphere.
(H/t Instapundit)

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