the sun

Our Sun is a big ball of hot, glowing gas. Since it doesn't have a solid surface, its outer layers rotate at different speeds as the Sun turns on its axis. A spot at the equator takes about 25 days to make a complete turn. But a spot near one of the poles takes about 10 days longer.

This might be little more than a good Trivial Pursuit question, except for one thing. The outer layers generate the Sun's magnetic field. The different rotation rates tangle and stretch the magnetic field, creating dark "sunspots" and outbursts of gas and radiation. These outbursts can affect life on Earth — knocking out satellites and power grids, and perhaps even changing the weather.

The intensity of the Sun's magnetic storms varies in an 11—year cycle. The cycle is expected to peak again next year or in early 2001, when scores or even hundreds of dark sunspots should speckle the Sun's surface. Sunspots appear when the magnetic field holds back the flow of hot gas from the Sun's int...