A recent report released by the National Research Council outlined scientific goals for the next decade and put knowledge of the sun and its weather patterns at the forefront. Now, following suit, the Institute for Astronomy from the University of Hawaii has released a report about the sun. About what? The roundness of the sun.
Apparently, the sun is just about the most round object ever measured. If you were compress the sun into the size of a beach ball, the differences between the widest and narrowest diameters is less than the width of a strand of human hair.
The sun should have a slightly bulged equator due to its 28-day rotation cycle. But the results show that if it had a diameter of one meter, the differences in the equator diameter and North-South pole diameter is only 17 millionths of a meter.
"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," says study leader Jeffrey Kuhn.
To obtain the most precise measurement of the sun's shape, the astronomers used the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory satellite. Using Earth-based imaging systems results in a distorted image because of the atmosphere. Out in space, however, there is no atmosphere to interfere with the photograph.
"The sun is very, very round, so it's difficult to measure any deviations in that roundness," said Kuhn. "It's only been in the last few years that we've been able to make decent shape observations."
The report by the National Research Council warned that the sun and solar weather patterns could be of concern in the future. The 85 scientists involved in the report have put understanding the sun, and the Earth-sun relationship at the top of their list of priorities.
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