The Flippin’ Solar Magnetic Field

Solar Magnetic Field About to Change

A Dec. 8 image of the Sun from the Solar Dynamics Observatory, showing regional magnetic field lines and plasma flowing along them in active regions. Courtesy SDO/NASA.
A Dec. 8 image of the Sun from the Solar Dynamics Observatory, showing regional magnetic field lines and plasma flowing along them in active regions. Courtesy SDO/NASA.

This is not “new” news, since it was announced earlier this year, but the Sun’s magnetic field is about to flip its polarity sometime in the next few weeks to a month. When this happens, the Sun’s polar magnetic fields weaken and then drop to zero.  Shortly thereafter, they emerge again, but with the opposite polarity. So, if one pole was “north”, it will be “south” after the flip, and the other will flip to “north”. This is really an outward effect of the Sun’s interior dynamo reorienting itself. This is a regular part of the solar cycle. The Sun does this every 11 years, regular as clockwork. Completely normal and nothing to be worried about.

It’s not completely clear yet WHY the Sun’s north pole flips south and the south pole flips north, although solar physicists are making great strides in understanding actions inside our star that cause this and other activity. They DO know that the new polarity builds up throughout the 11-year-long sunspot cycle. Sunspots are those dark spots that appear on the visible surface of the Sun. They’re regions where the temperatures are cooler than the surrounding surface and thus they appear darker. Astronomers at Stanford University, who are monitoring this regular magnetic field flip, described the process in a press story released last month.

“New polarity builds up throughout the 11-year solar cycle as sunspots – areas of intense magnetic activity – appear as dark blotches near the equator of the sun’s surface. Over the course of about a month, sunspots disintegrate, and gradually that magnetic field migrates from the equator to one of the sun’s poles.

As the surviving polarity moves toward the pole, it erodes the existing, opposite polarity, said Todd Hoeksema, a solar physicist at Stanford since 1978 and director of the Wilcox Solar Observatory. The magnetic field gradually reduces toward zero, and then rebounds with the opposite polarity.

“It’s kind of like a tide coming in or going out,” Hoeksema said. “Each little wave brings a little more water in, and eventually you get to the full reversal.”

When the Sun’s polarity flips, it does actually affect the rest of the solar system, but not in any psychic or alien way. And yes, there ARE people out there who interpret a magnetic field flip as some kind of paranormal thing. Nothing could be further from the truth, which is that the Sun is an active, evolving, magnetized sphere of plasma, and as such, it has constantly changing characteristics in ALL its magnetic fields. It has an overall magnetic field, and it also has localized magnetic fields which cluster around sunspots and are suspected to be involved in heating of the corona in some way. So, if you start to see hysterical ravings about the “mysterious” magnetic field flips of the Sun and how it will bring on a new age of psychic unity or something unlikely, put on your skeptic hat and turn to actual solar science for some answers.

Actually, the effects of a solar magnetic field flip are pretty cool to study. The changes propagate out to the “edge” of the heliosphere (the limit of the Sun’s influence in space).  Since these flips coincide with higher sunspot activity and more bursts of charged particles (through flares and coronal mass ejections), we can expect to see more auroral displays. The interactions with Earth’s magnetic field can affect our technology (how much it does so depends on the severity of any space weather “attack” fostered by the Sun’s activity), and might cause satellite operators to put their instruments into “safe mode” for a short while. We are currently in the middle of “solar max”, which is supposed to be the maximum amount of activity during a sunspot cycle. This has been a somewhat quiet solar max, so it will be interesting to see how the magnetic field reversal plays out.

If you want to read a more detailed description of what happens during a polarity flip, check out the Science Daily article from August 6th of this year or the recent press release from Stanford University, whose Wilcox Solar Observatory has been watching the Sun since the mid 1970s and is providing very good long-range looks at the Sun’s activity.

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