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According to Dearborn, "In Europe, where the telescope was first invented and used, it informed them that sunspots existed. There was a belief that the heavens were perfect, and frequently people see only what they expect to see. So when they first saw sunspots, they were amazed. They didn't really know what sunspots were, because they didn't have the tools to measure the magnetic fields that were producing these things, but they definitely sparked curiosity."

There is some debate over which European was first to discover sunspots. The credit is usually shared by Johann Goldsmid (known as Johannes Fabricius) of Holland, Galileo Galilei of Italy, Christopher Scheiner of Germany, and Thomas Herriot of England, all of whom claimed to have discerned sunspots sometime in 1611. All four men observed sunspots through telescopes, and made drawings of the changing shapes by hand, watching the spots traverse the visible surface of the sun. These drawings were the first steps toward understanding sunspots.
 Dave Dearborn
Dave Dearborn talks about the development of the telescope and viewing sunspots.

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 .Sunspot Drawing from Rosa Ursina But these scientists could not agree on what they were seeing. Some, like Galileo, believed that sunspots were part of the sun itself, features like spots or clouds. But other scientists, especially Scheiner, who was a Jesuit priest, believed the Catholic Church's doctrine that the heavens were perfect, representing the divine perfection of God. This doctrine is often seen as an extension of Aristotle's view of the heavens as ideal and unchanging. To admit that the sun had spots or blemishes that moved and changed would be to undermine that perfection! So Scheiner argued that the spots he and Galileo were seeing must be planets or moons orbiting the sun, and he interpreted his observations in the light of that argument.

Perhaps less entangled in the doctrine of the period, Galileo made a breakthrough. By observing the sun closely over a period of several weeks, Galileo noticed the shape of the sunspots became foreshortened as they approached the edge of the visible sun. He realized that this would only happen if the spots were objects on the surface of the sun, and not if they were spherical planets or moons passing before the sun. So he concluded that the spots must be on the surface. Though he admitted that he was unsure what the spots were, he suggested that they could be clouds.

History Page 3of 4


Observatory  1998 The Exploratorium.