Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Spiral galaxies abound in the universe, but spiral sunspots are definitely an unusual twist. Sunspots appear dark only because they are relatively cool - about 4,000 degrees compared to the 6,000 degrees Celsius of the surrounding solar surface. Associated with surface magnetic fields, their numbers increase and decrease in a regular pattern tracing the Solar Activity cycle . A maximum in sunspot numbers occurs every 11 years with the next maximum expected around the year 2001.
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