In fact, it's like many stars in the universe. The sun makes up 99.86 percent of the solar system's mass, and provides the energy that both sustains and endangers us. The energy radiates through the middle layer, then bubbles and boils to the surface in a process called convection. Charged particles, called the solar wind, stream out at a million miles an hour. Sunspots Magnetic fields within the sun slow down the radiation of heat in some areas, causing sunspots.
Sunspots appear as dark patches.
Sunspot activity peaks every 11 years. The next peak is due in 2000. During this so-called solar maximum, the sun will bombard Earth's atmosphere with extra doses of solar radiation. The last peak, in 1989, caused power blackouts, knocked satellites out of orbit and disrupted radio communications. Though NASA scientists aren't predicting any record-setting space weather in 2000, the peak is expected to be above average.