Galileo Galilei, Sunspot observations
Paper
3 May 1612http://www.loc.gov/exhibits/vatican/vatican.html#itmotpmahd
Galileo helped to create a new science partly because of his extraordinary skills as an observer, which enabled him to create and use the first telescope. These drawings represent sunspots— whose existence proved that the sun was not the perfect, unchanging body that traditional Aristotelian cosmology considered it to be. Galileo’s work received strong support for a long time from Maffeo Barberini, the future Pope Urban VIII, though his Dialogues on Two World Systems and Copernican views would eventually be condemned by Rome.
(via scientificillustration)