Tuesday, September 13, 2011

The Sounds of the Sun; What can they tell us?

Perhaps quite a bit:

Listening to the sun may improve space weather forecasts
Scientists at Stanford University find they can predict sunspots up to two days before they appear, which could help better foretell solar flares.

August 20, 2011|By Amina Khan, Los Angeles Times

Sunspots, those dark regions on the surface of the sun whose high magnetic activity has ripple effects for Earthlings, seem to emerge and fade without warning. But now, by listening to the sounds the sun makes, scientists have managed to predict when a sunspot will appear up to two days beforehand.


A team of Stanford University researchers tracked sound-generated activity at different points on the sun's surface and found that sound waves that would normally take an hour to cross from one point to the next traveled 12 to 16 seconds faster when a sun spot was emerging — a surprise, since the researchers expected to see perhaps only one second or so shaved off.

By monitoring sound waves about 37,000 miles below the solar surface, the physicists said, they can predict the emergence of a sunspot one to two days before it appears, depending on how large it is.

"It's very exciting that we can detect them before they become visible," said lead author Stathis Ilonidis, a graduate student studying solar physics at Stanford University. But he added that more data would be needed to show that their results hadn't turned up false positives.

The findings could prove useful to scientists looking to tie sunspots to the space weather events generated days later. Because areas of high magnetic activity are closely linked to dangerous solar activity — from flares to violent coronal mass ejections — being able to understand that magnetic activity may help predict oncoming solar storms and allow people to prepare for them, rather like putting up storm windows in response to a hurricane warning. [...]

Interesting. Thanks to new technologies, we are rapidly finding out a lot more about the sun than we ever knew before. But of course, the more we find out, the more questions we have, too.

I wonder how much we will find out by 2013, when the predicted solar maximum peaks? And it looks like there will be plenty of activity in the meantime too:

More Mammoth Solar Flares Expected From 'Old Faithful' Sunspot, Scientists Say
An active region of the sun that blasted out powerful solar storms four days in a row last week likely isn't done yet, scientists say.

Officially, the flare-spouting region is called sunspot 1283. But space weather experts have dubbed it "Old Faithful," after the famous geyser in the United States' Yellowstone National Park that goes off like clockwork. And the solar Old Faithful should erupt again before it dissipates, researchers said.


From Sept. 5-8, sunspot 1283 produced four big flares and three CMEs. Two of the flares were X-class events and two were M-class flares. (Strong solar flares are classified according to a three-tiered system: X-class are the most powerful, M-class are of medium strength and C-class are the weakest.)

While the rapid motion previously observed in sunspot 1283 seems to have died down a bit, Young said, the sunspot looks poised to erupt again sometime soon.

"There's a good probability that we're still going to see at least another M-class flare, possibly another X-class flare," Young told SPACE.com.

It's not uncommon for sunspots to pop off a number of powerful flares in quick succession the way 1283 has done, he added. That seems to be the natural order of things.

"When you see one big flare, your chances of seeing another one are pretty good," Young said. [...]

Well it looks like there will be lots more "chances" over the next couple of years.

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