Galileo's Instruments of Discovery
With these various instruments, Galileo Galilei was able to look into space and change our view of the universe.
- By Sarah Zielinski
- Smithsonian.com, July 20, 2009
At night, this small device could be used as a nocturnal to tell time. During the day, it could be used as an horary disk to tell time and also to determine when the sun and moon would rise and set. Similar devices went into use in Europe around the eighth century. This one dates to 1647.