Galileo turned his telescope to the sky beginning in the autumn of 1609 revealing a heavenly world which was not quite so heavenly anymore. In his Sidereus Nuncius, published in 1610, Galileo described the sights he saw with his telescopes, much more improved than the first spyglasses which first appeared in Holland in 1608. Galileo reported that the moon had craters and mountains. He showed by mapping the Pleiades, Praesepe, and parts of Orion, that more stars existed than can be seen with the naked eye. Galileo discovered that Venus had a cycle which could not be explained by its rotation around the earth, but could be explained by both the Earth's and Venus's rotations around the sun. Finally, Galileo discovered the existence of four "stars" orbiting Jupiter, dealing yet another blow to the commonly held notion that the Earth is the center of the universe. By suggesting that the sun, and not the Earth, was the center of the universe, Galileo had put the Earth into the heavens and the heavens in the world of the imperfect. Aristotelian astronomy, not merely a basis for understanding how the stars moved, but also the foundation of philosophy and even scriptural interpretation, would be shattered if people chose to believe Galileo. And Galileo had proof.

The astronomy group of the History 333 class at Rice University seeks to reproduce Galileo's astronomical findings. Are Galileo's findings reproducible? Did Galileo tell all that he did? Are we able to build a telescope which is exactly like Galileo's? Did Galileo really see that big crater on the moon that he drew in Sidereus Nuncius? Why didn't Galileo sketch the Orion Nebula into his star map of Orion? How easy is it to observe the phases of Venus? Why didn't Galileo see the satellites of Jupiter with his 10X telescope? What improvements might Galileo have made on his telescope that he didn't tell us about? Find out what our research has revealed about these questions and more.

Making a Galilean Telescope

Using a Galilean Telescope

Looking at Orion

Looking at Pleiades

Looking at the Moon

Looking at Venus

Looking at Comet Hyakutake

Other resources which may be useful:

• The History of the Telescope
• The Moon
• The Satellites of Jupiter
• The Ptolemaic System
• The Copernican System
• The Galileo Project at Rice University

The members of our group are Rebecca Brown, Travis Dunn, Karl Haushalter, and Tom Williams. Updates of our research and of the research done by other groups in our class can be found at the History 333 Newsgroup.