Geocentric Theory Vs. Heliocentric Theory

Geocentric Theory Vs. Heliocentric 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

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


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




Where would you have to aim if we launched a missile from Alaska and tried to hit Ecuador?


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


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


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


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



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




Stellar Parallax◦ The apparent movement of stars among farther

stars


Stellar Parallax◦ The apparent movement of stars among farther

stars


Meteoric Evidence


As the earth rotates we see more meteors when we are the leading face



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Geocentric Theory Vs. Heliocentric Theory