Galileo is one of the most famous scientists ever, both for his groundbreaking discoveries and his willingness to stand by his theories in opposition to conventional thought. His persecution by the Catholic church is one of the more celebrated cases of extreme conservatism in history.
Less is known about Galileo himself, however. He had a background in art, often drawing and painting. This training helped him realize what he was observing in the heavens. Specifically, his understanding of chiarascuro (the use of shading to indicate depth) led him to realize that the forms he observed on the moon were craters and mountains. In short, he realized that the moon had a texture, in contradiction to the concept of the moon as perfect in its smoothness. Without his training in the arts, he would not have been able to make this discovery.