5 Early Greek AstronomyPtolomy (140 AD): Still believed that Earth was center of Universe (geocentric theory). Noticed that Aristotle’s model did not explain planetary movements.Planets and stars moved in EPICYCLES. In other words planets move in perfect CIRCLES WITHIN CIRCLES!
6 Ptolemaic System Jupiter Mars Saturn Earth & Moon Venus Mercury Sun Ptolemaic SystemMarsJupiterPtolemy’s system provided the intellectual framework for all discussion of the universe for nearly 1600 years!! So in a very true sense, this idea was stupendously successful even though we now know that it was incorrect.SaturnEarth & MoonVenusMercurySun
10 Copernicus 1. Earth is not the center of “everything.” 2. All the planets revolve around the Sun! (heliocentric theory)3. Stars are very much farther away than the Sun4. Any motion of the stars is a result of the Earth’s rotation5. Still used “perfect” circles for the orbits.
11 Changing Ideas is Not Easy. Copernicus was no fool. He waited until his own death before he published his new ideas.On March 5, 1616, Copernicus' work was banned from being taught and discussed by the Congregation of the Index "until corrected." It stayed on this list of prohibited books and teachings until 1822!!!!
12 Italian scientistGalileo Galilei (late 1500s - early 1600s): First to point the refracting TELESCOPE towards the heavens. He studied the movement and orbits of many nearby planets in our solar system.Offered PROOF to Copernicus’s Heliocentric Model of our Universe.Led to the discovery of the moons of Jupiter
14 The Great Compromise Tycho Brahe (1546-1601) Danish Nobleman Experimentalist & Observer.Made very careful measurements of star’s positions. Earth must be stationary.
15 Tycho developed a system that combined the best of both worlds. Tychonic ModelTycho developed a system that combined the best of both worlds.He kept the Earth in the center of the universe, so that he could retain Aristotelian physics and Ptolemy’s geocentric idea.The Moon and Sun revolved about the Earth, and the shell of the fixed stars was centered on the Earth.But Mercury, Venus, Mars, Jupiter, and Saturn revolved about the Sun.