1. Earth is in the center with everything revolving around it Everything orbits in a perfect circle There is a sphere of stars that surrounds the system like a shell. Geocentric Model (Plato/Aristotle) 400 B.C. Earth is in the center with everything revolving around it Everything orbits in a perfect circle There is a sphere of stars that surrounds the system like a shell. 400 B.C. Earth is in the center with everything revolving around it Everything orbits in a perfect circle There is a sphere of stars that surrounds the system like a shell. 400 B.C. Earth is in the center with everything revolving around it Everything orbits in a perfect circle There is a sphere of stars that surrounds the system like a shell. 400 B.C. Geocentric Model (Plato/Aristotle) Geocentric Model (Plato/Aristotle) Geocentric Model (Plato/Aristotle)

2. Earth is in the center Everything orbits around Earth in a circle Each planet moves in a circle while it revolves Sphere of stars surrounds system Epicycle Model (Ptolemy) 150 A.D. Earth is in the center Everything orbits around Earth in a circle Each planet moves in a circle while it revolves Sphere of stars surrounds system Earth is in the center Everything orbits around Earth in a circle Each planet moves in a circle while it revolves Sphere of stars surrounds system Earth is in the center Everything orbits around Earth in a circle Each planet moves in a circle while it revolves Sphere of stars surrounds system Epicycle Model (Ptolemy) 150 A.D.

3. Sun is in the center Everything orbits around the Sun in a circle Seven Planets Sphere of stars surrounds system Heliocentric Model (Copernicus) 1500 A.D. Sun is in the center Everything orbits around the Sun in a circle Seven Planets Sphere of stars surrounds system Heliocentric Model (Copernicus) 1500 A.D. Sun is in the center Everything orbits around the Sun in a circle Seven Planets Sphere of stars surrounds system Heliocentric Model (Copernicus) 1500 A.D. Sun is in the center Everything orbits around the Sun in a circle Seven Planets Sphere of stars surrounds system Heliocentric Model (Copernicus) 1500 A.D.

4. Sun is in the center Everything orbits with an elliptical path Six Planets Elliptical Model (Kepler) 1600 A.D. Elliptical orbits are like squashed circles Sun is in the center Everything orbits with an elliptical path Six Planets Elliptical Model (Kepler) 1600 A.D. Elliptical orbits are like squashed circles Sun is in the center Everything orbits with an elliptical path Six Planets Elliptical Model (Kepler) 1600 A.D. Elliptical orbits are like squashed circles Sun is in the center Everything orbits with an elliptical path Six Planets Elliptical Model (Kepler) 1600 A.D. Elliptical orbits are like squashed circles

5. Sun is in the center Everything orbits with an elliptical path Eight? Planets Current Model 1930 A.D. Elliptical orbits are like squashed circles Sun is in the center Everything orbits with an elliptical path Eight? Planets Current Model 1930 A.D. Elliptical orbits are like squashed circles Sun is in the center Everything orbits with an elliptical path Eight? Planets Current Model 1930 A.D. Elliptical orbits are like squashed circles Sun is in the center Everything orbits with an elliptical path Eight? Planets Current Model 1930 A.D. Elliptical orbits are like squashed circles