Theories of Planetary Motion Part 2: Heliocentric Theory

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

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

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!!!)

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

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)

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

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)

Heliocentric Theory Parallax:

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

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…

1992 !!!