(2) Sunspots

Image courtesy of Big Bear Solar Observatory.

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Basic Facts About Sunspots

Dark splotches on the sun, like the one shown in close-up, are sunspots. They are almost always seen in pairs and in groups of pairs.

Sunspots are dark because they are the coolest places on the sun. Magnetic fields about as strong as those of a horseshoe magnet (which is 1000 times stronger than the Earth's surface magnetic field) keep heat from flowing up to the surface here. The sun's differential rotation (faster at low than high latitudes is critical in producing sunspots).

Solar flares (enormous explosive releases of energy from the sun) are most likely to occur in sunspot groups that are growing rapidly and rotating like a hurricane. The number of sunspots on the sun at any given time varies in an ll-year cycle as does the number and severity of disturbances in space weather. Constantly monitoring the development of sunspot groups is one important job of spaceweather forecasters.

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