If you thought the Sun was round -- you'd be right. But astronomers this week said the Sun is so round it's nearly perfect in its roundness. So round that astronomers said if they scaled it to the size of a beach ball, it would be so round that the difference between the widest and narrow diameters would be much less than the width of a human hair.
It's not that scientists didn't know the Sun was round mind you, they just didn't know how round. Using an instrument on NASA's Solar Dynamics Observatory satellite, astronomers said they were able to "measure the solar shape with unprecedented accuracy." The study, done by Jeff Kuhn and Isabelle Scholl of the Institute for Astronomy, University of Hawaii at Manoa; Rock Bush of Stanford University, and Marcelo Emilio of Universidade Estadual de Ponta Grossa, Brazil, says that the sun rotates every 28 days, and because it doesn't have a solid surface, it should be slightly flattened.
It is this tiny flattening has been studied with many instruments for almost 50 years to learn about the sun's rotation, especially the rotation below its surface, which we can't see directly, Kuhn said. He added that this solar flattening is remarkably constant over time and too small to agree with that predicted from its surface rotation. This suggests that other subsurface forces, like solar magnetism or turbulence, may be a more powerful influence than expected.
"For years we've believed our fluctuating measurements were telling us that the sun varies, but these new results say something different. While just about everything else in the sun changes along with its 11-year sunspot cycle, the shape doesn't," Kuhn said.
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