the 36-inch refractor at Lick Observatory in California. The discovery, a testament to his extraordinary eyesight, made him quickly famous. The moon was later named Amalthea . Sources: http://en.wikipedia.org/wiki/Jupiter , http://www.windows.ucar.edu/tour/link=/jupite r/discovery.html   christiee's Recommendations The Worlds of Galileo: The Inside Story of Nasa's Mission to Jupiter Amazon List Price: $29.99