Flippin' tosser: Sun's magnetic field poised to SWIVEL on it - NASA
About to go to space? Better postpone your trip
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The solar magnetic field will completely "flip" within the next three or four months, according to NASA.
The dramatic-sounding event happens every 11 years. The Sun's magnetic activity follows a cycle, and as it reaches a maximum the poles weaken, reversing polarity.
In June last year, the Sun's northern polar field became more positively charged than the southern polar field - what's called a "reversal" of polarity. What's called a "flip" is considered to have taken place when the both fields change polarity. The Sun's magnetic field is weak but extends far beyond Pluto, NASA explains.
The current solar cycle, Solar Cycle 24, is the weakest of modern times, with fewer sunspots than scientists predicted and a decline in the number of sunspots per group.
As is its wont, NASA includes a pretty but useless "artist's concept" with its press release - this time it's of the heliospheric current sheet, and the artist has decided to colour it purple. Instead, here's a rather more useful chart of what the Sun is doing, via Stanford's Leif Svalgaard, who suggests "the Sun may be entering a new regime of very low activity".
Leif Svalgaard, Hansen Experimental Physics Laboratory, Stanford
Source presentation:[pdf]
The field reversal was first detected by the Hinode observatory satallite operated by the Japanese space agency JAXA.
Astronauts and spaceships ought to watch out too. According to NASA, during field reversals, the current sheet* becomes very wavy. A wavy current sheet, in turn, affects cosmic rays, "high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy", which are a danger to people and vehicles in space. ®
* "a sprawling surface jutting outward from the Sun's equator where the sun's slowly-rotating magnetic field induces an electrical current... [of] only one ten-billionth of an amp per square meter (0.0000000001 amps/m2)... 10,000 km thick and billions of kilometers wide."
