NASA Scientist Maps Sun's Plasma Flow; Could Eventually Help Predict Solar Flares
The sun has vast swirling cells, like conveyor belts of superheated plasma, that circle the hot materials on the inside toward the cool surface and then back under again. Some of the cells are about 620 miles across, while some are closer to 20,000 miles — which is almost the distance around the earth. But scientists had long imagined, and seen limited evidence of, even larger convection cells. Now, researchers at NASA have proved their existence.
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In an article published Friday in the journal Science, David Hathaway and two co-authors describe the enormous convection cells that largely define the sun's structure and are likely linked to earth-impacting events, such as solar storms. The way the sun's energy moves on its surface leads to the flares that can cause satellite interference and electrical problems here on earth. "The analogy with earth weather systems is very close," Hathaway told The Verge. "The same way weather systems carry moisture in the earth's atmosphere, these things are carrying magnetic fields in the sun's surface and interior."
The sun's surface swirls for the same reason water boils. At 27 million degrees Fahrenheit, the sun's core is hot enough to boil the hydrogen that mostly makes up the sun's matter. That boiling, or convection, happens in a hierarchy of convection swirls. Some are relatively small and short lived (called granules), existing within the bigger, planet-sized ones (supergranules). For the past 45 years, that hierarchy had led scientists to believe, in theory, that there was probably a bigger order of convection going on. But those had been difficult to track. According to The Verge, these new giant cells flow at about 10 yards per second, which is pretty much standing still when viewed from 93 million miles.
The team of researchers identified them, though, by tracking the supergranules for months. One thing this helps clear up is the rotation of the sun's equator, which flows faster than other parts of the star. But there's still a lot they don't know.
"The observation we're dying to get is whether there is any indication in these flows about where new sunspots are going to emerge," Hathaway told The Verge. That's the most interesting thing to us non-scientists because predicting sunspots can help predict solar flares. A sunspot is an area of high magnetic activity that discourages convection. Sunspots often predict flares, or massive ejections of energy that get tangled up in the earth's own magnetic field. The results range from power outages to the auroras. So far, though, scientists have not been able to connect the dots between plasma flow and magnetism. "I think we will get a better hand on that given the fact that we now see these flows," Hathaway told The Verge.
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