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Galileo was the first to show that sunspots are surface features on the Sun carried around by its rotation. Be very careful ever observing sunspots with the naked eye. Galileo spent the last twenty years of his life blind from careless observations of the Sun. The best procedure is to magnify the Sun's image with a small telescope and project it into a viewing chamber shielded from outside light. Sunspots are magnetic disturbed regions cooler than the surrounding areas. They have temperatures of four thousand to forty-five hundred degrees Kelvin versus fifty-seven hundred degrees on average for the solar photosphere. The gas motions in a sunspot are controlled by intense magnetic fields.
