Galileo's observation of sunspots. Illustration and Italian text about the pioneering sunspot observations made over several months in 1612 by Italian astronomer Galileo Galilei (1564-1642). Galileo was one of the first people to observe sunspots, making his observations using his telescope to observe them indirectly and at sunset and sunrise. He published his observations in 'Istoria e Dimostrazioni Intorno Alle Macchie Solari e Loro Accidenti' (1613, History and Demonstrations Concerning Sunspots and their Properties). Sunspots are areas of magnetic activity that are cooler than the rest of the Sun's surface.