ALBUQUERQUE - The first measurements of weather just beneath the surface of the Sun reveal remarkable similarities to weather patterns on Earth and other planets.
The Sun's weather is of course nothing like Earth -- perpetually far hotter than the worst days here in this Southwest city. However, its variations seem to mimic short-term storms, from localized wind flows to large-scale "hurricanes" that could swallow up to 18 Earths. Other solar trends are similar to years-long climate patterns like El Nino.
Deborah Haber and Brad Hindman, both of the University of Colorado, led a team of researchers analyzing more than 5 years of data from the SOHO spacecraft. They studied movements of material in a thin layer near the surface of the Sun. They presented their findings here today at the 200th meeting of the American Astronomical Society.
"For the first time, we can see large-scale weather systems developing on and just below the surface of a star," Haber said. The research revealed steady gales of 45 mph and more violent gusts up to 100 mph, all heading in myriad directions. Some patterns changed daily, others lasted for years.
On Earth, scientists know that heat, mostly from the Sun, drives all weather. Researchers examine terrestrial surface temperatures, ocean currents and other indicators to understand what causes specific storms and climate patterns.
"The big difference is that we don't know what drives the weather on the Sun," Hindman said in an interview.
He suspects, however, that the primary driving force is the same: Heat rises, or convects, pulling in surrounding atmosphere, causing wind. He said the same principles probably hold generally true for stars and planets.
"Any object that convects probably has very weather-like patterns," Hindman said.
The recent discovery of weather on a brown dwarf bolsters this idea. Brown dwarfs are mid-sized objects larger than Jupiter but not massive enough to be full-blown stars. Yet these strange objects have weather, too, storms that dwarf even the largest storms on Jupiter.
The newly spotted weather on the Sun could help researchers better understand a strange aspect of the Sun's surface, said John Leibacher of the National Solar Observatory in Arizona. Leibacher, who was not involved in the new study, explained the mysterious "differential rotation" long observed on the Sun: Sunspots on its mid-section are known to move more quickly than spots at higher latitudes -- up to 20 percent faster.
Leibacher said the key to this differential rotation may lie in a better understanding of the weather just below the surface, which the new study provides.
The new study may yield other important findings over time.
One curious pattern observed, Haber explained, is a breeze in the Sun's northern hemisphere that reversed direction in 1998.
"We are seeing a global weather shift on the Sun like the El Nino pattern here on Earth," Haber said.
She added that the flow may be tied to a reversal in magnetic fields that the Sun experiences every 11 years, she said. This reversal is tied closely to the Sun's overall activity, which peaks every 11 years, sending stronger space storms toward Earth.
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