The Sun’s almost perfectly round shape baffles scientists
2012-08-22 0:00

From: Phys.org

The sun is nearly the roundest object ever measured. If scaled 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.

The sun rotates every 28 days, and because it doesn’t have a solid surface, it should be slightly flattened.

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.

Now 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) have used the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory satellite to obtain what they believe is the definitive -- and baffling -- answer.

Because there is no atmosphere in space to distort the solar image, they were able to use HMI’s exquisite image sensitivity to measure the solar shape with unprecedented accuracy. The results indicate that if the Sun were shrunk 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 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.

Kuhn, the team leader and first author of an article published today in Science Express, said, "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."

This work was supported by NASA grants to Stanford University and the University of Hawaii.

More information: "The Precise Solar Shape and Its Variability," by J.R. Kuhn et al., www.sciencemag.org/content/early/2012/08/15/science.1223231


Article from: phys.org





Related Articles
Secrets of the Sun
Swiss woman dies after attempting to live on sunlight alone
Wonders of sun, moon and sky


Latest News from our Front Page

60 Years of Research Links Gluten Grains to Schizophrenia
2015-03-31 1:05
Does the consumption of gluten-containing grains contribute to psychiatric disorders such as schizophrenia? Believe it or not, this question has been asked for well over 60 years by researchers who stumbled upon evidence that the removal of gluten from the diet results in improved symptoms, or conversely, that gluten grain consumption leads to higher prevalence of both neurological and psychiatric problems. Reports ...
A Sour Deception: Citric Acid Comes From GMO Black Mold, Not Fruit
2015-03-30 23:32
Just what is your food made of, anyway? Try industrial synthesis, genetically modified mold secretions, hydrochloric acid, mercury-contaminated caustic soda, ferrocyanide… and, of course, lots of GMO corn. If common ingredients like “citric acid” and “ascorbic acid (Vitamin C)” sound normal and familiar enough that you practically conjure up an image of the flourishing orchard they were grown in – then ...
Thousands of migrants dumped on Britain as French wriggle out of border promise
2015-03-30 19:56
Thousands of migrants could be dumped on Britain’s doorstep if France tears up a historic border agreement, it was claimed last night. Officials have vowed to do “everything in their power” to wriggle out of a treaty moving the UK border to Calais. The besieged town’s mayor Natacha Bouchart is prepared to spark a major diplomatic row by opening the frontier ...
Richard III laid to rest at Leicester Cathedral
2015-03-30 18:36
King Richard III was today laid to rest at Leicester Cathedral - more than 500 years after his death in battle. The monarch, who reigned from 1483 to 1485, was the last of the Plantagenet dynasty. Actor Benedict Cumberbatch read a poem by Carol Ann Duffy during the service. Also in attendance was Robert Lindsay, who played Richard III in a version ...
Sweden - A new paradise for Romani beggars
2015-03-30 17:33
Thanks to the European Union and freedom of movement that follows with membership Sweden has been flooded with gypsies from Eastern Europe. Most member states have cracked down hard on the phenomenon of organized begging with legislation and forceful evictions so the Romani (colloquially known as Gypsies) who are engaged in this venture have moved their business to the country where ...
More News »