What effects do sunspots have on the Earth?

Sunspots are actually the harbingers of magnetic activity on the Sun which can accelerate particles near the Sun to high energies, and eject them during flare events and Coronal Mass Ejections (CMEs). It is the CME events, most common when sunspots are in evidence, which travel to Earth in a few days and can interfere with the terrestrial plasma environment, causing magnetic sub-storms, auroral activity, and influence everything from telecommunications to the electrical power grid. Here is what a CME looks like, thanks to the Solar Heliospheric Observatory located in space.

Also, there seems to be a correlation between years of enhanced solar activity (heightened sunspot numbers) and the severity of weather systems in the northern hemisphere. No one really understands what the connection is.

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