The surface of the sun undergoes period outbursts of enormous power. Great Arcs of gas and magnetic fields with the power of many atomic bombs. This image of a particularly large solar prominence was observed by ultraviolet detectors aboard the Skylab space station in 1979. Flares are even more violent rupturing the surface of the sun in just minutes. Temperatures in the flares can get as high as 100,000,000 degrees K. effect of flare .
Solar activity changes in step with the solar cycle.
The changing surface of the sun has a great effect on the Earth. 1 CME anim 2 Satellites get fried by Coronal Mass Ejections. Powerlines get overloaded. Astronauts can be in big trouble. As we rely more on space for telecommunications space weather will be more of an issue.