1. Theories of Planetary Motion
Part 2: Heliocentric Theory

2. Heliocentric Theory Copernicus (1473 – 1543)
1st to say that the sun was the center of the universe (all things revolve around it) with supportive information
Mathematically solved “relative” size of solar system (based on earth’s orbital size which he labeled 1 A.U.)
Calculated period of motion of known planets

3. Heliocentric Theory Copernicus’ Heliocentric Theory:
There is no one center to all celestial spheres
The center of earth isn’t the center of the universe
All spheres revolve around the sun
(4 – 7) The motion of stars, sun & planets is due to earth’s motion; not their motion

4. Heliocentric Theory Copernicus (cont.)
He never pursued proving his theory due to:
Lack of equipment to find proof
Couldn’t explain lack of parallax
Extreme pressure from church (“stop your crazy talk, or die!!!)

5. Heliocentric Theory Tycho Brahe (1546 – 1601)
Genius or Crazy Drunk?!?!?!?
Made extremely accurate measurements of celestial movements
Still believed earth was center of universe
Accurately documented the path of Mars
Couldn’t mathematically prove his findings

6. Heliocentric Theory Johannes Kepler (1571 – 1630) Student of Brahe
Brilliant mathematician
His work stated, the earth isn’t the center of the universe, celestial bodies do not possess uniform circular motion (they move in ellipses)
Contradicted Brahe (they hated each other)

7. Heliocentric Theory Johannes Kepler (cont.)
Used Brahe’s work + his math to create 3 Laws of Planetary Motion
Galileo (1564 – 1642)
Invented telescope
His findings supported heliocentric theory
Explained parallax & retrograde motion

8. Heliocentric Theory Galileo:
Parallax = can only be witnessed if you are up close (we weren’t close enough to notice until we looked through telescope)

9. Heliocentric Theory
Parallax:

10. Heliocentric Theory Retrograde Motion:
Not caused by epicycles, but rather a faster planet “lapping” the slower planet as they orbit the sun
Retrograde Motion of Venus
Retrograde Motion of Mars

11. Heliocentric Theory Galilean Timeline:
1616 – Told to abandon Copernican Theory
1632 – Sentenced to house arrest
1642 – Galileo dies
1741 – Church accepts Copernican Theory
Church clears Galileo’s name in…

12. 1992 !!!