Hello Pat,

Many sunspots, especially the bigger ones, can be seen by the naked eye, if one is foolish enough to look without some kind of protection. It is indeed true that there are records from CHinese astronomers discussing dark spots on the Sun, dating back to 28 BC and perhaps further. It is not true that Galileo discovered sunspots however. Thomas Harriot and Fabricius had published results recording sunspots in 1609-1610 a year or so before Galileo's recorded observations. Christoph Scheiner was also observing sunspots around 1611. Galileo did claim to have discovered them but the hostorical records prove otherwise. Galileo was the first, I believe, to point out that sunspots were in fact on the Sun rather than a phenomenon of Earth's atmosphere or the passage of Mercury in front of the Sun.

David

Hi Pat,

I believe they were looking at the sun on very hazy days or else near sunset. If a sunspot is large enough you don't need a sunspot to see it. A little more information is here:

http://www.hao.ucar.edu/P...imeline.A.html#800bc

http://findarticles.com/p..._1988_Oct/ai_6955852

Actually, I have heard that Galileo's blindness was not caused by looking at the Sun, but by other causes (see Galileo's Daughter by Dava Sobel). He actually used the telescope to project the image of the Sun on another surface, as you should.

Cheers,

Terry