Chapter 3: Telescopes © BRIEF 20141

2 Galileo Galileo Galilei ( )

© BRIEF Galileo Astronomy Prior to 1600: All astronomical observations for the last 4000 years were naked eye Mayan Dresden Codex Medieval Quadrant for measuring altitude of stars “Great Mural Quadrant” Tycho Brahe

© BRIEF Galileo Question: Did Galileo discover the telescope? NO. He was just the first one to turn it to the heavens. Galileo did make his own telescopes from the designs of others. Earliest known illustration by Giovanbattista della Porta Early Telescope of Galileo First Telescope of Galileo

© BRIEF Galileo What Galileo saw: Mountains and Valleys on the Moon. No longer a smooth surface as ancients thought Satellites of Jupiter (named for the Medici family whom funded Galileo: Medicean Stars) Phases of Venus Sunspots What Galileo did: His observations began to prove the old Aristotelian view of the world was wrong Began to show that the Church’s view of the universe was incorrect Published “Starry Messenger” of his findings and argued that theologians should not interfere with study of science. Drawing of the Moon Galileo’s Starry Messenger Drawing of the Phases of Venus Sunspots

© BRIEF Galileo Saturn Venus: phases like … Jupiter and its moons The Moon The stars in Orion’s sword Images using telescope very much like Galileo’s.

© BRIEF Telescopes Jupiter’s Moon – Observations by Galileo Sketch of his observations of the moons of Jupiter on the back of an envelope Translation of Galileo’s summary of his observations

© BRIEF Galileo Questions?

© BRIEF Galileo …almost 400 years ago lenses were combined to make a telescope, and a telescope was pointed to the sky by the Italian scientist Galileo The vast nighttime sky, points of light, until…

© BRIEF Galileo Saturn Venus: phases like … Jupiter and its moons The Moon The stars in Orion’s sword Images using telescope very much like Galileo’s. He didn’t understand what he saw when he looked at Saturn: he thought it had “arms” Venus showed phases like the moon over many months, convincing him that Venus was going around the sun as the moon goes around the earth. He also realized from watching the motion of Jupiter’s moons that they were in orbit around Jupiter. He saw several examples of objects not in orbit around the earth, as everyone had believed.