Sun's Magnetic Field About To Flip (Video)

The Sun’s magnetic field is about to flip. According to recent measurements gathered by NASA-supported observatories, the vast solar magnetic field is on the verge of making its regularly occurring reversal. The solar magnetic field reverses in polarity approximately every 11 years.

“It looks like we’re no more than three to four months away from a complete field reversal,” stated solar physicist Todd Hoeksema of Stanford University. “This change will have ripple effects throughout the solar system.”

The Sun’s magnetic field reverses polarity right around the peak of the solar cycle — the upcoming reversal will mark the peak of Solar Cycle 24. That’s not to say that powerful solar flares won’t occur after the peak — simply that half of ‘solar max’ is still to come.

"Astronomers anticipate the reversal of the sun's global magnetic field." Image Credit: Science@NASA

Solar physicist Phil Scherrer, also at Stanford, explains the reversal: “The sun’s polar magnetic fields weaken, go to zero and then emerge again with the opposite polarity. This is a regular part of the solar cycle.”

NASA has more:

The poles are a herald of change. Just as Earth scientists watch our planet’s polar regions for signs of climate change, solar physicists do the same thing for the sun. Magnetograms at Stanford’s Wilcox Solar Observatory have been tracking the sun’s polar magnetism since 1976, and they have recorded three grand reversals — with a fourth in the offing.

A reversal of the sun’s magnetic field is, literally, a big event. The domain of the sun’s magnetic influence (also known as the “heliosphere”) extends billions of kilometers beyond Pluto. Changes to the field’s polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space.

When solar physicists talk about solar field reversals, their conversation often centers on the “current sheet.” The current sheet is a sprawling surface jutting outward from the sun’s equator where the sun’s slowly rotating magnetic field induces an electrical current. The current itself is small, only one ten-billionth of an amp per square meter (0.0000000001 amps/m2), but there’s a lot of it: the amperage flows through a region 10,000 km thick and billions of kilometers wide. Electrically speaking, the entire heliosphere is organized around this enormous sheet.

During field reversals, the current sheet becomes very wavy. Scherrer likens the undulations to the seams on a baseball. As Earth orbits the sun, we dip in and out of the current sheet. Transitions from one side to another can stir up stormy space weather around our planet.

During the reversal, cosmic rays — high-energy particles accelerated to almost light speed by supernova explosions and other extreme events — are also impacted. Such cosmic rays pose significant dangers to astronauts and to space probes. It’s also thought that they may have some impact on the Earth’s climate and cloud formation. “The current sheet acts as a barrier to cosmic rays, deflecting them as they attempt to penetrate the inner solar system. A wavy, crinkly sheet acts as a better shield against these energetic particles from deep space.”

Signs of the upcoming field reversal are becoming more and more obvious, according to the researchers: “The sun’s north pole has already changed sign, while the south pole is racing to catch up,” Scherrer stated. “Soon, however, both poles will be reversed, and the second half of solar max will be underway.”

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