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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 - PowerPoint PPT Presentation
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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
Problems with The Geocentric 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.
Heliocentric Theory
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
Tycho Brahe
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
Johannes Kepler
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
Galileo
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
Newton
Earth Motions has two components◦ Rotation: moving on an axis◦ Revolution: around the sun
We can prove both motions without going to space
Evidence that the Earth Moves
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 Rotation
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