Sun's core rotates faster than surface

Astronomers observing the Sun have concluded that its core rotates faster than its surface; a conclusion that could help piece together the story of the Sun's formation.

A cross section of the Sun’s inner portions.
Credit: Newton Science Magazine


The core of the Sun rotates almost four times as quick as the solar surface, according to a new study.

A team of scientists made the conclusion by measuring the time it takes an acoustic wave to travel from the surface of the Sun and back again.

The results could help astronomers piece together a model of how our closest star formed.


Read more about the Sun from BBC Sky at Night Magazine:


Scientists had previously assumed the core was rotating at about the same speed as the surface.

But the new results suggest that, after the Sun formed, streams of particles called solar winds may have slowed the rotation of the outer part of the Sun.

The team arrived at this conclusion by studying surface acoustic waves in the Sun’s atmosphere. These acoustic waves are produced by the plasma in the Sun’s convective zone.

Some of them penetrate to the Sun’s core, where they interact with gravity waves.

By measuring the acoustic waves in the Sun, the scientists determined the time it takes one to travel from the surface of the Sun to its centre, and back again.

This travel time is influenced slightly by the motions of the gravity waves.

The team identified the movements of the gravity waves and made their calculations using 16 years of observations by NASA’s Solar and Heliospheric Observatory.

“The most likely explanation is that this core rotation is left over from the period when the sun formed, some 4.6 billion years ago,” says Roger Ulrich, a UCLA professor emeritus of astronomy and co-author of the study.

“It’s a surprise, and exciting to think we might have uncovered a relic of what the Sun was like when it first formed.”

Carousel image: SoHO, a joint project of the European Space Agency and NASA
Like this article? Why not:
Saturn’s moon offers glimpse of Earth’s past
previous news Article
Six structures listed at Jodrell Bank
next news Article
We use cookies to improve your experience of our website. Cookies perform functions like recognising you each time you visit and delivering advertising messages that are relevant to you. Read more here