1. Developing a Model of the Solar System THE HISTORY OF ASTRONOMY

2.  About 1600 B.C.  Recorded position of planets  Times of eclipses  Early Chinese, Central American, and North European cultures show evidence of studying astronomy BABYLONIANS

3.  Thales  Used Babylonian data to predict eclipses  Eratosthenes  Measured the circumference of the Earth  Hipparchus  Produced first star catalog and recorded the names of constellations ANCIENT GREEKS

4.  Heraclides  330 B.C.  Developed the first solar system model with the Earth at the center  Aristarchus  270 B.C.  Developed a heliocentric model of the solar system GEOCENTRIC VERSUS HELIOCENTRIC

5.  200 A.D.  Librarian of Alexandria  Believed Heraclides’ geocentric model of the solar system to be correct  His model seemed to adequately explain the motion of the planets, but it was complicated. PTOLEMY

6.  1500’s  Believed in the heliocentric model of the solar system  The Heliocentric model was not popular with the church COPERNICUS

7.  1580’S  Built the Danish Observatory  Measured positions of planets and stars  Showed that the sun was much farther from the Earth than the moon is TYCHO BRAHE

8.  1600’s  Brahe’s student  Used Brahe’s data to formulate Laws of Planetary Motion  Used elliptical orbits instead of circular orbits KEPLER

9.  1620’s  Developed laws of motion  Natural versus forced  Rest versus uniform motion  Used a telescope to discover  Spots on the sun  Mountains and “seas” on the moon  Multiple stars in the Milky Way  Phases of Venus  Jupiter’s moons GALILEO

10.  1680’s  Developed the law of universal gravitation  Developed the first reflecting telescope NEWTON