Transcript Theories of Planetary Motion

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:
1. There is no one center to all celestial
spheres
2. The center of earth isn’t the center of the
universe
3. All spheres revolve around the sun
4. (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
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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)
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Heliocentric Theory
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Parallax:
Heliocentric Theory
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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
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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 !!!