STANFORD, California -- According to
measurements from NASA-supported observatories, the sun's vast magnetic
field is about to flip in less than four months.
The sun's magnetic field changes polarity approximately every 11
years at the peak of each solar cycle as the sun's inner
magnetic dynamo re-organizes itself. The coming reversal will mark the
midpoint of Solar Cycle 24. Half of "solar max" will be behind us, with
half yet to come.
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.
Solar magnetic field reversals affect the Sun's "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 entire heliosphere is organized around this
enormous sheet. During field reversals, the current sheet becomes very wavy. Transitions from one side
to another can stir up stormy space weather around Earth.
The current sheet also 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.
