ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY
Sunspot observations made in 1769. Drawings like these were made by tracing sunspots (dark areas) on an image of the Sun projected by a lens onto an observation screen. Here, a large sunspot is shown moving as the Sun rotates. The observations are labelled 1-5 and dated in the key below to November and December 1769. Sunspots, first observed with telescopes in 1610, are areas of magnetic activity that are cooler than the rest of the Sun's surface. These observations were published in volume 64 of Philosophical Transactions, the journal of the Royal Society in London, England.
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