Shop Windows to the Universe

Science, Evolution, and Creationism, by the National Academies, focuses on teaching evolution in today's classrooms. Check out the other publications in our online store.
Magnetic field lines from a computer simulation of the solar corona show some of the complexity of the Sun's magnetic field. Colors on the Sun's surface show the strength of the magnetic field (yellow is largest).
Click on image for full size

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 0.5 Gauss). Since the Sun's surface is more than 12,000 times larger than Earth's, the overall influence of the Sun's magnetic field is vast.

The magnetic field of the Sun actually extends far out into space, beyond the furthest planet (Pluto). This distant extension of the Sun's magnetic field is called the Interplanetary Magnetic Field (IMF). The solar wind, the stream of charged particles that flows outward from the Sun, carries the IMF to the planets and beyond. The solar wind and IMF interact with planetary magnetic fields in complex ways, generating phenomena such as the aurora.

Overall, the basic shape of the Sun's magnetic field is like the shape of Earth's field... or like the field of a simple bar magnet. However, superimposed on this basic field (called a dipole field) is a much more complex series of local fields that vary over time. Places where the Sun's magnetic field is especially strong are called active regions, and often produce telltale sunspots. The local magnetic field in the neighborhood of a large sunspot can be as strong as 4,000 Gauss... much, much greater than the Sun's average field. Disruptions in magnetic fields near active regions can spawn energetic explosions on the Sun such as solar flares and Coronal Mass Ejections. The degree of complexity of the Sun's field waxes and wanes over the course of each sunspot cycle.

The exact nature and source of the Sun's magnetic field are areas of ongoing research. Turbulent motions of charged plasmas in the Sun's convective zone clearly play a role. Some of the Sun's magnetism may even be a remnant from the primordial cloud from which the Sun formed.

Some of the spectacular structures seen in the solar atmosphere, such as solar prominences and coronal loops, are fantastic visible indicators of material flowing along magnetic field lines which arc thousands of kilometers above the Sun's surface.

Last modified June 23, 2010 by Randy Russell.

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.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

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

The Magnetic Field

The force of magnetism causes material to point along the direction the magnetic force points. This property implies that the force of magnetism has a direction. As shown in the diagram to the left, the...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

Pluto

Pluto is a frigid ball of ice and rock that orbits far from the Sun on the frozen fringes of our Solar System. Considered a planet, though a rather odd one, from its discovery in 1930 until 2006, it was...more

Planetary Magnets

The Earth is a good example of a planetary dipole, where the lines of force point in a direction out of the South (magnetic) Pole and into the North (magnetic) Pole. Planets can also show evidence of quadrupoles...more

Active Regions on the Sun

An active region on the Sun is an area with an especially strong magnetic field. Sunspots frequently form in active regions. Active regions appear bright in X-ray and ultraviolet images. Solar activity,...more

Sunspots

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are cooler than their surroundings. A large sunspot might have a central temperature of...more

Sunspots and Magnetic Fields

Sunspots are caused by extremely strong, localized magnetic fields on the Sun. "Jet streams" of plasma that form deep within the Sun's convective zone produce powerful magnetic fields. When these loops...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! NASA AGU AGI NSF