An artist’s concept of the heliospheric current sheet. The rotating Sun is located in the center. The current sheet circles the Sun’s equator like a wavy skirt around a ballerina’s waist.
The sun’s magnetic field permeates the entire solar system called the heliosphere. All nine planets orbit inside it. But the biggest thing in the heliosphere is not a planet, or even the sun. It’s the current sheet — a sprawling surface where the polarity of the sun’s magnetic field changes from plus (north) to minus (south). A small electrical current flows within the sheet, about 10−10 A/m². The thickness of the current sheet is about 10,000 km near the orbit of the Earth. Due to the tilt of the magnetic axis in relation to the axis of rotation of the sun, the heliospheric current sheet flaps like a flag in the wind. The flapping current sheet separates regions of oppositely pointing magnetic field, called sectors.
As Earth orbits the sun, it dips in and out of the undulating current sheet. On one side the sun’s magnetic field points north (toward the Sun), on the other side it points south (away from the Sun). South-pointing solar magnetic fields tend to cancel Earth’s own magnetic field. Solar wind energy can then penetrate the local space around our planet and fuel geomagnetic storms.
View an associated news item at https://www.nasa.gov/content/goddard/the-suns-magnetic-field-is-about-to-…