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.

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January 8, 2009: Magnetic fields could reveal exoplanets -- Physics World
October 30, 2008: Magnetic portals connect Sun and Earth -- Science@NASA
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