1. Famous Astronomers

2. Ptolemy Thought the Earth was at the center of the universe and that the other planets revolved around it (GEOcentric model) Thought the Earth was at the center of the universe and that the other planets revolved around it (GEOcentric model) Incorrect but predicted the motion of the planets Incorrect but predicted the motion of the planets

3. Copernicus Said the sun was at the center of the universe and all planets orbited it (HELIOcentric model) Said the sun was at the center of the universe and all planets orbited it (HELIOcentric model) Major changes in science took place after this Major changes in science took place after this

4. Tycho Brahe Used a mural quadrant to plot the positions of the stars and moon (helped future astronomers) Used a mural quadrant to plot the positions of the stars and moon (helped future astronomers) Thought the sun and moon revolved around Earth but that all other planets revolved around the sun Thought the sun and moon revolved around Earth but that all other planets revolved around the sun

5. Johannes Kepler Using Brahe’s data, he figured out that all the planets revolve around the sun in an elliptical orbit Using Brahe’s data, he figured out that all the planets revolve around the sun in an elliptical orbit Also found that the sun is not exactly in the center of those orbits Also found that the sun is not exactly in the center of those orbits Developed the three laws of planetary motion Developed the three laws of planetary motion

7. Galileo First use of telescope to observe space First use of telescope to observe space Discovered craters and mtns. on the moon, sunspots on the sun, and moons of other planets Discovered craters and mtns. on the moon, sunspots on the sun, and moons of other planets

8. Newton Showed that all objects in the universe attract each other through gravitational force. Showed that all objects in the universe attract each other through gravitational force. The force of gravity depends on the mass of the objects and the distance between them. The force of gravity depends on the mass of the objects and the distance between them. This explains why the planets orbit the most massive object in our solar system: the sun This explains why the planets orbit the most massive object in our solar system: the sun

9. Hubble Proved that other galaxies existed beyond the Milky Way by using a better telescope Proved that other galaxies existed beyond the Milky Way by using a better telescope His data confirmed the beliefs of other astronomers that the universe is bigger than our solar system. His data confirmed the beliefs of other astronomers that the universe is bigger than our solar system.