Temporary dark markings on the surface of the Sun, known as sunspots, have been observed since ancient times. As seen from Earth, though, most sunspots are too small to be observed with the naked eye. It was not until the invention of the telescope that sunspots could be observed with regularity. Sunspots were a regular feature on the face of the Sun in the early seventeenth century; however, sunspots all but disappeared later in that century for a period of time lasting into the eighteenth... więcej
Salem Press Encyclopedia of Science, 2019. 2p.