Sunspots come in pairs with opposite magnetic polarity. If we could bury a giant horseshoe magnet beneath the surface of the Sun, it would produce a magnetic field similar to that generated by a sunspot pair.
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Windows to the Universe original artwork by Randy Russell using an image from NASA's TRACE (Transition Region and Coronal Explorer) spacecraft.
Sunspots and Magnetic Fields
Sunspots are caused by very
strong magnetic fields on the Sun. The best way to think about the very complicated process of sunspot formation is to think of
magnetic "ropes" breaking through the visible surface
(photosphere) of the Sun. Where the rope comes up from the solar surface is one sunspot and where the rope plunges into photosphere is another sunspot.
As you can see in the picture to the left, one sunspot has North magnetic polarity and one sunspot has South magnetic polarity.
Scientists
believe the differential
rotation of the Sun is the underlying cause of the magnetic ropes on the Sun. Since the gaseous sphere of
the Sun rotates more quickly at its equator than at its poles, the Sun's overall
magnetic field becomes distorted and twisted over time. The twisted
field lines eventually come through the photosphere, showing their
presence as sunspots.
When the tangled fields reach a "breaking point", like a rubber band
that snaps when wound too tight, huge bursts of energy are released as the
field lines reconnect. This can lead to solar
flares and Coronal Mass Ejections (CMEs).
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