Monday 12 August 2013

Get ready for the sun to flip its magnetic field

We're just a few months away from the sun flipping its magnetic field, a change that only happens about once every 11 years.







We're hitting the peak of the solar cycle and the sun will be pulling off quite the gymnastics move to mark the occasion. According to NASA, a flip of the sun's magnetic field is only a few months away. It's dramatic, but it's also normal behavior.
"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," says Stanford solar physicist Phil Scherrer.
NASA Science News describes the changes:
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.

NASA-sponsored solar observatories have been keeping an eye on changes in the sun that indicate the field reversal is imminent. Nobody on Earth is likely to wake up and notice a sudden change in the sun's magnetic field, so we'll have to wait for the official announcement from scientists.

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