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Geocentric Theory Vs. Heliocentric Theory. Problems with The Geocentric Theory. Problem #1: Planets seemed bright and close at times but dim and far away at other times Ptolemy’s Answer: Eccentric circles This model offended the ancients because the earth was not the center anymore
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Problems with The Geocentric Theory • Problem #1: Planets seemed bright and close at times but dim and far away at other times • Ptolemy’s Answer: Eccentric circles • This model offended the ancients because • the earth was not the center anymore • Problem # 2: Planet some times move slower and backwards • Ptolemy’s answer: Retrograde motion • Planets moved in epicycles • Crystal Sphere moved deferent • Problems with this theory is that its inaccurate and complex
Heliocentric Theory • Copernicus studied mathematics, astronomy, medicine, law, and theology • Wrote a book called “The Revolutions” • With this book answered the questions people had for a moving Earth • Problem #1: A Spinning Earth would fly apart • Answer: The sky would be far more likely to fall apart because it is bigger and therefore moves faster • Problem #2: The birds would be left behind by a moving earth • Answer: Earth drags the atmosphere along with it; including the birds • Problem #3: If earth was rotating around the Sun, then the stars should be bigger and smaller • Answer: Stars are so far away that you can’t see the difference in distance.
Tycho Brahe • One of the most accurate astronomers in history • He did not accept the Copernican Theory • He held to a variation of the geocentric theory: The sun revolved around the earth and the everything else revolved around the sun • He recorded remarkably precise observations for the next twenty years • He became the imperial mathematician and started analyzing his data
Johannes Kepler • Outstanding Christian and a brilliant mathematician • Persecuted by the Roman Catholic Church and left Austria to work for Tycho Brahe • Began to study Mars, making hundreds of pages of calculations • Published a book called New Astronomy- in which he describe 2 new laws • He published a third law later • Greatest contribution was proving that planets orbits were elliptical not circular
Galileo • First to use a telescope for Astronomy • Fascinated by Venus and its phases • If Venus was in a crystal sphere, there should not be phases • Fascinated by Saturn • Could see two things poking out of the planet, what we know as rings • Fascinated by Jupiter • Could see Jupiter's four closest moons • Realized that the moons revolved around Jupiter • Smaller bodies rotate around larger bodies
Newton • English Mathematician • Story: Newton was sitting in an apple orchard thinking about the moon and how it orbits the earth. He saw an apple fall off a tree and had his Eureka moment. • The same force that pulled the apple to ground is the same force that pulls the moon around the earth • The universal Law of Gravitation: Any two bodies attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them
Evidence that the Earth Moves • Earth Motions has two components • Rotation: moving on an axis • Revolution: around the sun • We can prove both motions without going to space
Evidence of Rotation • Earth’s Shape • Is earth a perfect sphere? • Earth bulges in the middle and slightly flattens at the spheres
Evidence of Rotation • Other planets have similar bulges • Jupiter and Saturn are the fastest spinning planets • They have the biggest bulge in the middle • Mercury and Venus have the slowest spin • They are almost perfect spheres • Since the equator is the fastest moving place on earth, it explains the bulge at the equator • The bulge is land trying to keep up with inertia
Evidence of Rotation • Wind Patterns If the earth did not rotate, warm air would rise from the heat of the equator and cold air would fall over the poles. • We would only get wind and storms from the north. • How do you explain most of our storms coming from the west? • The earth’s rotation actually deflects the wind patterns into a curved path
Evidence of Rotation • Where would you have to aim if we launched a missile from Alaska and tried to hit Ecuador?
Evidence of Rotation • Focault Pendulum • Jean Focault set up a 220ft wire with 61lb iron ball at the end of it. • He started swinging the ball back and forth • Within a short time the ball started moving a different directions • Only a rotating earth could explain the direction change of the pendulum • At the equator, the pendulum does not change directions • At the North or South Poles, the pendulum does a complete circle in 24 hours
Evidence of Rotation • Direct observation • Astronauts on the moon saw the earth’s entire surface in 24 hours • The moon does not revolve around the earth once everyday • The earth must be rotating
Evidence of Revolution • The second great motion of earth is its revolution • Two kinds of evidence • Earth and Sun moving • Just the earth moving
Evidence of Revolution • The Sun’s apparent motion • The suns position amongst the stars changes throughout the year • Does this prove Geocentric Theories? • The Sun follows an apparent pathway through the stars • We call this the ecliptic: using stars a background • It is explained by the changing viewpoint of earth
Evidence of Revolution • Why do we have Seasons? • Are we closer to the sun during the summer? • During summer we are actually the farthest away from the sun • Three reasons why its warmer during the summer: • 1st: greater number of daylight hours, the earth has more time absorb the sun’s heat • 2nd: higher angle rays of the sun are more concentrated • 3rd: higher angle rays loose less energy traveling through the atmosphere
Evidence of Revolution • Solstices and Equinoxes • The Sun appears to move north and south from season to season • Summer solstice: when the sun is directly of Tropic of Cancer • Winter solstice: when the sun is directly over the Tropic of Capricorn • Vernal and Autumnal equinox: When the sun is directly over the equator
Evidence of Revolution • Stellar Parallax • The apparent movement of stars among farther stars
Evidence of Revolution • Stellar Parallax • The apparent movement of stars among farther stars
Evidence of Revolution • Meteoric Evidence
Evidence of Revolution • As the earth rotates we see more meteors when we are the leading face
