1. EARLY ASTRONOMERS

2. Aristotle 3384 BC- 322 BC GGreek Philosopher BBelieved in a geocentric model of the universe EEarth was the center and planets revolved around it AAlso believed in four basic elements- earth, fire, water, and air TThough a 5 th element aether made up the celestial bodies

3. Ptolemy  90 AD-168 AD  Astronomer and Mathematician  Geocentric model of the universe  Developed tables for the rising and setting of sun, appearance of the stars

4. Nicholas Copernicus  1473-1543  Polish astronomer and mathematician  First to propose a heliocentric model for the universe  The sun was at the center and Earth revolved around it

5. Galileo  1564-1642  Italian Physicist  Developed the first telescope  Lead to the discovery of 4 of Jupiter’s Moons  Tracked the phases of Venus  Believed in the heliocentric theory of the Universe  Catholic church tried him in an Inquisitition

6. Galileo  Excommunicated, but Pope John Paul in the 1980’s declared him innocent

7. Johannes Kepler  1571-1630  The first to describe the Motion of Planets based on Geometry  Tides were cause by the Moon.  Kepler's first Law: The orbit of a planet about the Sun is an ellipse with the Sun's center of mass at one focus.  Kepler's second Law: A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.  Kepler's third Law: The squares of the periods of the planets are proportional to the cubes of their semi-major axes.

8. Edwin Hubble  1889-1953  American Astronomer and Mathematician  Discovered Galaxies beyond are own- the Milky Way  Confirmed the Doppler Shift which states the shift of the light spectra is in direct proportion to the distance from Earth