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How does the Sun's magnetic field work?

The sun has a large and complex magnetic fieldA field of force that is generated by electric currents. The Sun's average large-scale magnetic field, like that of the Earth, exhibits a north and a south pole linked by lines of magnetic force..

Magnetic fields are created by things that are magnetic (like iron magnets) or by moving charged particles. A magnetic field is the description of the force a magnetic object exerts in the space surrounding the magnetic object. A force is a push or pull. To learn more about forces and magnetic fields, please visit The University of Colorado Physics 2000 website.

When charged particles move around really fast they create magnetic fields. The Sun is made of positively charged ionsAn atom that has become electrically charged by the gain or loss of one or more electrons. and negatively charged electronsA negatively charged elementary particle that normally resides outside (but is bound to) the nucleus of an atom. in a state of matter called plasmaPlasma consists of a gas heated to sufficiently high temperatures that the atoms ionize. The properties of the gas are controlled by electromagnetic forces among constituent ions and electrons, which results in a different type of behavior. Plasma is often considered the fourth state of matter (besides solid, liquid, and gas). Most of the matter in the Universe is in the plasma state.. Since the Sun is made of charged particles, magnetic fields are created by the movement of the particles.

The Sun's charged particles move in three ways due to the Sun's high temperatures and the movement of its axis, which influence each other to make the Sun's magnetic field complex:

  1. The Sun's high temperatures cause the positively charged ions and negatively charged electrons that make up its plasma to move around a lot. The moving plasma creates many complicated magnetic fields that twist and turn.
  2. The extremely hot plasma that blows off the Sun as the solar windA stream of charged particles, mostly protons and electrons, that escapes into the Sun's outer atmosphere at high speeds and streams out into the solar system. also causes a magnetic field.
  3. The plasma in the Sun also rotates around the Sun's axis. The plasma near the poles rotates slower than the plasma at the equator causing twisting and stretching of magnetic fields, too.
Sun's Magnetic Field

The Sun’s magnetic field is shown in a series of illustrated images with the poles and equator indicated. The magnetic field linesImaginary lines that indicate the strength and direction of a magnetic field. The orientation of the line and an arrow show the direction of the field. The lines are drawn closer together where the field is stronger. Charged particles move freely along magnetic field lines, but are inhibited by the magnetic force from moving across field lines. change as the Sun rotates. After 1, 2, and 3 rotations the magnetic field line gets progressively wrapped around the Sun, becoming stretched as it nears the equator. After many rotations the magnetic field is complex and wrapped tightly around the Sun in many loops.

Image Credit: José Francisco Salgado, PhD (Adler Planetarium)

Those motions of the Sun's plasma interact and influence each other to form the Sun's entire magnetic field.

Close to the Sun's surface the magnetic fields are twisted and complex. Further away from the Sun's Surface, some general trends emerge. The magnetic field is stronger near the poles and weaker at the Sun's equator. However, even at the Sun's equator, where the magnetic field is weaker, it is still around 100 times stronger than the Earth's magnetic field.

In addition to being complex, the Sun's magnetic field is also large. It influences the motion of charged particles well beyond the orbits of the known planets, to distances of around 75-100 times the distance of the Earth to the Sun.

NASA Principal Investigator: Dave McComas
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Last Updated: 6 June 2014
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