The Sun's Magnetic Field
The electric currents in the Sun generate a complex magnetic field with extends out into interplanetary space to form the interplanetary magnetic field. As the Sun's magnetic field is carried out through the solar system by the solar wind, the Sun is rotating. Its rotation winds up the magnetic field into a large rotating spiral, known as the Parker spiral, named after the scientist who first described it.
In the image above, it's easy to see why the neutral current sheet is often called the "ballerina skirt". The Parker spiral is indicated by the arrows. Image is courtesy of J. Jokipii, University of Arizona.
The magnetic field is primarily directed outward from the Sun in one of its hemispheres, and inward in the other. This causes opposite magnetic field directions in the Parker spiral. The thin layer between the different field directions is described as the neutral current sheet. Since this dividing line between the outward and inward field directions is not exactly on the solar equator, the rotation of the Sun causes the current sheet to become "wavy", and this waviness is carried out into interplanetary space by the solar wind. In addition, every eleven years the entire magnetic field of the Sun "flips" -- the north magnetic pole of the Sun becomes the south, and vice versa. The flip takes place at solar maximum. The Sun's Magnetic Field in the News:
June 10, 2008: NASA
plans to visit the sun -- Science@NASA
June 3, 2008: Giant "tornadoes" seen erupting from the sun -- National Geographic May 28, 2008: Plasma twisters seen on the sun -- Nature May 27, 2008: Cartwheel coronal mass ejection -- Science@NASA April 2, 2008: Hinode: Source of the slow solar wind and superhot flares -- ESA March 20, 2008: Science with the solar space observatory Hinode -- Astronomy & Astrophysics March 18, 2008: STEREO: The sun's corona unraveled in 3D -- Sky & Telescope February 26, 2008: Sun-like star flips its magnetic field like our sun: First observation -- Science Daily February 22, 2008: International solar mission to end following stellar performance -- NASA February 13, 2008: Sun-like star flips its magnetic field -- Astronomy.com January 14, 2008: Ulysses spacecraft flies over Sun's north pole -- NASA JPL January 7, 2008: 'Maverick' sunspot heralds new solar cycle -- New Scientist January 2, 2008: Third instrument for NASA's Solar Dynamics Observatory arrives at Goddard -- NASA GSFC November 28, 2007: Odd little star has magnetic personality -- Gemini Observatory November 19, 2007: An extended magnetic reconnection X-line in the solar wind -- ACE News November 16, 2007: Solar Dynamics Observatory instrument to peer inside the Sun arrives at Goddard -- NASA GSFC November 6, 2007: An X class flare region on the Sun -- APOD October 24, 2007: Solar telescope soars into sky on jumbo-jet-sized balloon -- Science Daily August 31, 2007: Scientists find elusive waves in Sun's corona -- Science Daily August 30, 2007: Scientists find elusive waves in solar corona -- NSF July 1, 2007: XMM-Newton reveals X-rays from gas streams around young stars -- Science Daily June 5, 2007: Hinode helps predict solar activity -- Astronomy.com June 1, 2007: XMM-Newson deciphers the magnetic physics around forming stars -- Science Daily June 1, 2007: Pioneering 3D view of near-Earth magnetic 'dance' -- Science Daily June 1, 2007: Secrets of the Sun's sizzling corona -- Australian Broadcasting Company March 22, 2007: Hinode studies the Sun -- Astronomy.com February 7, 2007: South pole flyby -- Science@NASA Click on images above to
learn more about them
A service of the Astrophysics
Science Division at NASA's GSFC
Questions and comments to: cosmicopia@cosmicra.gsfc.nasa.gov Curator: Beth Barbier, SP Systems Responsible NASA Official: Dr. Tycho von Rosenvinge Privacy Policy and Important Notices |
HOME In the News History Ask Us Great Links Glossary Site Map Search NASA |
Last modified: July 7, 2008
|