30th December 2013
The sun has fully "flipped upside down", with its north and south poles reversed
to reach the midpoint of Solar Cycle 24, Nasa has said.
Now, the magnetic fields have once again started moving in opposite directions
to begin the completion of the 22 year long process which will culminate in the poles switching once again.
"A reversal of the sun's magnetic field is, literally, a big event," said Nasa’s Dr. Tony Phillips.
"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."
To mark the event, Nasa has released a visualisation of the entire process.
At the beginning, in 1997, the video shows the sun with its positive polarity on the top (the green lines),
and the negative polarity on the bottom (the purple lines).
Over the next 11 years, each set of lines gradually move toward the opposite pole, eventually showing a complete flip.
By the end, both set of lines representing the opposing magnetic fields begin to work their way back, which will eventually culminate in the completion of the full 22 year magnetic solar cycle in approximately 11 years, before the whole process starts over again.
"At the height of each magnetic flip, the sun goes through periods of more solar activity,
during which there are more sunspots, and more eruptive events such as solar flares and coronal mass ejections,"
said Nasa’s Karen C. Fox.
"Cosmic rays are also affected," added Dr. Phillips.
"These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy."http://www.independent.co.uk/news/science/video-sun-has-flipped-upside-down-as-new-magnetic-cycle-begins-9029378.html?origin=internalSearch