The sun is round ...

Very, very, very round.

The sun is the roundest natural object known to humans, according to new research. University of Hawaii researcher Jeffrey Kuhn and his colleagues used NASA's space-based Solar Dynamics Observatory to precisely measure the sun's shape. A precise understanding of the sun's roundness and the factors that shift its shape, such as sub-surface turbulence, could shed new light on changes in the Earth's climate. From National Geographic:

If the sun were a meter-wide (3.3-foot-wide) beach ball, Kuhn said, the variation in the sun's shape from the highest to the lowest point would be about 17 microns—less than the width of a fine human hair, according to the SDO measurements… Study leader Kuhn said his team is going to update computer models of the sun's cycle to see if and how the highly accurate shape affects their behavior.
"We're not done with measurements, though. We need to follow a full 11-year solar cycle to make sure the sun isn't fooling us," Kuhn said. "By doing that we can improve the accuracy even further."

"Sun Is Roundest Natural Object Known"