Sun observed as the most perfect sphere ever in universe

Sun is the most perfect sphere with a perfect shape in the Universe, says scoientists who measured the dimensions of the Sun. The researchers used the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory satellite to obtain the answer for the most baffling question about the earlier concept of slightly flattened surface of the sun.

The Sun is the roundest sphere in the Universe ever measured. If scaled to the size of a beach ball, the difference between the widest and narrowest diameter of the Sun would be much less than the width of a human hair.

The Sun takes a complete rotation in every 28 days, and owning to the absence of a solid surface, it should be slightly flattened. This small flattening has been studied using many instruments for last 50 years to learn about the Sun's rotation, especially the rotation below its surface, which cannot be seen directly.

Since there is absence of any atmosphere in the space that could distort the solar image, the scientists were able to use HMI's exquisite image sensitivity to measure the solar shape with unprecedented accuracy.

The study was conducted by Jeff Kuhn and Isabelle Scholl (Institute for Astronomy, University of Hawaii at Manoa), Rock Bush (Stanford University), and Marcelo Emilio (Universidade Estadual de Ponta Grossa, Brazil) and the results of the study indicate that if the Sun were compressed to a ball one meter in diameter, its equatorial diameter would be only 17 millionths of a meter larger than the diameter through its north-south pole, which is its rotation axis.

They also found that the solar flattening is significantly constant over time and was 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.

The details study has been recently published in Science Express.

-With inputs from ANI