History Modern Research Glossary Sunspots - Introduction HOME Dark spots, some as large as 50,000 miles in diameter, move across the surface of the sun, contracting and expanding as they go. These strange and powerful phenomena are known as sunspots. This resource will allow you to explore the nature of sunspots and the fascinating history of our efforts to understand them. What You'll Find in Each Section The "HISTORY" section discusses the importance of the sun to ancient cultures and their understanding of sunspots. The section also looks at how the development of the telescope began to change our understanding of sunspots. A simple method for viewing sunspots on your own is included. The development of new technology has increased our knowledge of how the sun works. The "MODERN RESEARCH" section explains what sunspots are and how they affect earth. In examining some of the physical workings of the sun we use some terms which may be unfamiliar. To help, a "GLOSSARY" of terms has been included. We hope you enjoy the Exploratorium's sunspots resource Credits Observatory  1998 The Exploratorium.