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Become a nitrogen atom in the nitrogen cycle in our Traveling Nitrogen Classroom Activity Kit/Game. See all our games, activity kits and classroom activities.

Sunspots serve as markers that help us see the rotation of the Sun.
Images courtesy SOHO (ESA & NASA). Animation by Windows to the Universe staff (Randy Russell).

# Rotation of the Sun

The Sun, like most other astronomical objects (planets, asteroids, galaxies, etc.), rotates on its axis. Unlike Earth and other solid objects, the entire Sun doesn't rotate at the same rate. Because the Sun is not solid, but is instead a giant ball of gas and plasma, different parts of the Sun spin at different rates.

We can tell how quickly the surface of the Sun is rotating by observing the motion of structures, such as sunspots, on the Sun's visible surface. The regions of the Sun near its equator rotate once every 25 days. The Sun's rotation rate decreases with increasing latitude, so that its rotation rate is slowest near its poles. At its poles the Sun rotates once every 36 days!

The interior of the Sun does not spin the same way as does its surface. Scientists believe that the inner regions of the Sun, including the Sun's core and radiative zone, do rotate more like a solid body. The outer parts of the Sun, from the convective zone outward, rotate at different rates that vary with latitude. The boundary between the inner parts of the Sun that spin together as a whole and the outer parts that spin at different rates is called the "tachocline".

The behavior of the Sun's magnetic field is strongly influenced by the combination of convective currents, which bring the charged plasma from deep within the Sun to the Sun's surface, and the differential rotation of the outer layers of the Sun. The complex, swirling motions that result make a tangled mess of magnetic field lines at the Sun's surface. Differential rotation is apparently the main driver of the 11-year sunspot cycle and the associated 22-year solar cycle. The notion that differential rotation and convective motion drive these cycles was first put forth in 1961 by the American astronomer Horace Babcock, and is now known as the Babcock Model.

(Note: If you cannot see the movie of the rotating Sun on this page you may need to download the latest QuickTime player.)

#### Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

## Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

## The Plasma State

Plasma is known as the fourth state of matter. The other three states are solid, liquid and gas.In most cases, matter on Earth has electrons that orbit around the atom's nucleus. The negatively charged...more

## The Photosphere - the "Surface" of the Sun

Most of the energy we receive from the Sun is the visible (white) light emitted from the photosphere. The photosphere is one of the coolest regions of the Sun (6000 K), so only a small fraction (0.1%)...more

## Sunspots

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are colder than the areas around them. A large sunspot might have a temperature of about...more

## The Solar Core

The solar core is made up of a really hot and dense gas (in the plasma state). The temperature of 15 million kelvins (27 million degrees Faranheit) keeps the core at a gaseous state. The core is where...more

## The Sun's Magnetic Field

The Sun has a very large and very complex magnetic field. The magnetic field at an average place on the Sun is around 1 Gauss, about twice as strong as the average field on the surface of Earth (around...more

## Starspots

You may have heard of sunspots that sometimes dot the "surface" of the nearest star, our Sun. Well, other stars have spots too. They are called starspots and are relatively cool, dark regions on the visible...more

## Sunspots and Magnetic Fields

Sunspots are caused by very strong magnetic fields on the Sun. The best way to think about the very complicated process of sunspot formation is to think of magnetic "ropes" breaking through the visible...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support!