Astrology is the belief that the location of the stars and planets on the day you were born determines your personality and your life. Astronomy is the study of the moon, stars, and other objects in space.

The ancient Greeks were some of the first people to try to explain why natural events occurred without reference to supernatural causes. books.com/books_hunt_living_in_ancient _greece.html

The Geocentric Theory The earth is located at the center of the universe and all the planets revolve around the earth. The earth is located at the center of the universe and all the planets revolve around the earth.

Why Geocentrism? The Geocentric theory was believed by the Catholic church especially because the church taught that God put earth as the center of the universe which made earth special and powerful. The Geocentric theory was believed by the Catholic church especially because the church taught that God put earth as the center of the universe which made earth special and powerful. The idea of the Earth actually moving was widely felt as foolish because, as they saw it, if the Earth was moving they would be able to feel it. The idea of the Earth actually moving was widely felt as foolish because, as they saw it, if the Earth was moving they would be able to feel it.

Aristotle ( B.C.) Developed an early model based on the concept of uniform circular motion. He placed the earth at the center of the universe and all of the planets, sun and stars around it. Developed an early model based on the concept of uniform circular motion. He placed the earth at the center of the universe and all of the planets, sun and stars around it. When Aristotle lived, if a person could “reason” why something happened, then experiments to see what would happen were not considered necessary. When Aristotle lived, if a person could “reason” why something happened, then experiments to see what would happen were not considered necessary.

When things change, the natural motion of earth materials was to seek the center of the universe. When things change, the natural motion of earth materials was to seek the center of the universe. This is why Aristotle placed the earth at the center of the cosmos. This is also his explanation for why objects fall when dropped. A dropped object is just following its natural tendency to seek the center of the universe. This is why Aristotle placed the earth at the center of the cosmos. This is also his explanation for why objects fall when dropped. A dropped object is just following its natural tendency to seek the center of the universe.

Aristotle reasoned that if the earth rotated about its axis, we should fly off into space. Since we don't, the earth must be stationary. Aristotle reasoned that if the earth rotated about its axis, we should fly off into space. Since we don't, the earth must be stationary. It would be almost 1900 years before Galileo introduced the concepts of gravity and inertia that explain why these effects are not observed even though the earth does move. It would be almost 1900 years before Galileo introduced the concepts of gravity and inertia that explain why these effects are not observed even though the earth does move.

Ptolemy (140 A.D.) Ptolemy advanced the geocentric theory in a form that prevailed for 1400 years because it visually appeared correct. He added mathematics to support the theory.

Ptolemy’s evidence: *The moon circled the earth. *The sun seemed to circle the earth too. *He concluded that the stars must also. Ptolemy’s problem: *Planet motions would not fit.

Ptolemy’s Problem Many supporters of the geocentric theory had one piece of evidence they couldn’t explain – the movement of MARS. Many supporters of the geocentric theory had one piece of evidence they couldn’t explain – the movement of MARS. Let’s take a break and investigate this movement. Let’s take a break and investigate this movement.

Mars’ Motion

How did Ptolemy explain this Problem? Ptolemy used geometric models to predict the positions of the sun, moon, and planets, using combinations of circular motion known as epicycles. Ptolemy used geometric models to predict the positions of the sun, moon, and planets, using combinations of circular motion known as epicycles. An epicycle is an orbit within an orbit. An epicycle is an orbit within an orbit. Having set up this model, Ptolemy then went on to describe the mathematics which he needed in the rest of the work. Having set up this model, Ptolemy then went on to describe the mathematics which he needed in the rest of the work.

Ptolemy’s Model – Epicycles Included

Ptolemy’s model Notice where the sun is! be.com/watch?v=V SeN6ZB1wqA

The Heliocentric Theory The Sun is the center of our solar system The Sun is the center of our solar system

Copernicus ( ) Polish astronomer who advanced the theory that the Earth and other planets revolve around the Sun. This was highly controversial at the time. Polish astronomer who advanced the theory that the Earth and other planets revolve around the Sun. This was highly controversial at the time. The Ptolemaic model had been widely accepted in Europe for 1000 years when Copernicus proposed his model. The Ptolemaic model had been widely accepted in Europe for 1000 years when Copernicus proposed his model.

Copernicus was told by many scholars that he should make his new findings accessible to others by publishing it. In 1543 the book called "On the revolutions of the heavenly bodies" was released. Copernicus's book had a great impact that angered the Catholic and Protestant Church. Copernicus was told by many scholars that he should make his new findings accessible to others by publishing it. In 1543 the book called "On the revolutions of the heavenly bodies" was released. Copernicus's book had a great impact that angered the Catholic and Protestant Church. The Church became so angry – the Geocentric theory made human beings seem closer to God and since earth was in the center that meant humans were more special. The heliocentric theory changed that perspective completely, making humans lose that position in the universe. The Church became so angry – the Geocentric theory made human beings seem closer to God and since earth was in the center that meant humans were more special. The heliocentric theory changed that perspective completely, making humans lose that position in the universe.

Galileo ( ) An Italian scientist, Galileo was renowned for his contributions to physics, astronomy, and scientific philosophy. He is regarded as the chief founder of modern science. An Italian scientist, Galileo was renowned for his contributions to physics, astronomy, and scientific philosophy. He is regarded as the chief founder of modern science. Galileo was condemned by the Catholic Church for his view of the cosmos based on the theory of Copernicus. Galileo was condemned by the Catholic Church for his view of the cosmos based on the theory of Copernicus.

Galileo’s Books Galileo published his discoveries and support for the Copernican model in two books published in 1616 and Galileo published his discoveries and support for the Copernican model in two books published in 1616 and Galileo was unusual for the time because he wrote in Italian rather than Latin like most scholars. Galileo was unusual for the time because he wrote in Italian rather than Latin like most scholars. Galileo also took great pains to make his books interesting often writing them in the form of dialogues rather than dry, boring dissertations. Galileo also took great pains to make his books interesting often writing them in the form of dialogues rather than dry, boring dissertations. After his first book, "Starry Messenger", was published he was warned by the Church not to publicly support Copernicism again. After his first book, "Starry Messenger", was published he was warned by the Church not to publicly support Copernicism again.

Trial Before the Inquisition Galileo abided by this edict until 1632 when he published "A Dialogue on the Two Chief World Systems". This book's outright support for the Copernican model and its ridiculing of the Ptolemaic model earned Galileo a trial before the Inquisition. Galileo abided by this edict until 1632 when he published "A Dialogue on the Two Chief World Systems". This book's outright support for the Copernican model and its ridiculing of the Ptolemaic model earned Galileo a trial before the Inquisition. Galileo was accused of heresy and sentenced to house arrest for life. However, he got off easily compared to fellow Italian Giordano Bruno who was burned at the stake in 1600 for teaching Copernican ideas. Galileo was accused of heresy and sentenced to house arrest for life. However, he got off easily compared to fellow Italian Giordano Bruno who was burned at the stake in 1600 for teaching Copernican ideas.Giordano BrunoGiordano Bruno

In 1992, the Roman Catholic Church finally repealed the ruling of the Inquisition against Galileo. The Church gave a pardon to Galileo and admitted that the heliocentric theory was correct. This pardon came 350 years after Galileo's death. In 1992, the Roman Catholic Church finally repealed the ruling of the Inquisition against Galileo. The Church gave a pardon to Galileo and admitted that the heliocentric theory was correct. This pardon came 350 years after Galileo's death.

Along comes Tycho… From 1576 to 1597, Danish astronomer Tycho Brahe ( ) made very detailed measurements of planetary positions. Tycho’s observations were made without a telescope as they weren’t invented just yet! Hmmm… wassup with my nose!?

Intrigue!? Johannes Kepler ( ), Tycho’s assistant, analyzed the data and found a problem! Johannes Kepler ( ), Tycho’s assistant, analyzed the data and found a problem! Orbits are NOT circular, Tycho… they’re elliptical (flattened circles). Orbits are NOT circular, Tycho… they’re elliptical (flattened circles). Planets’ speed as they orbit are not constant … they speed up when closer to the Sun! … but, WHY!? Planets’ speed as they orbit are not constant … they speed up when closer to the Sun! … but, WHY!? Secrets, secrets … do I smell bacon!?

Not just great hair… Sir Isaac Newton (1643–1727), an English physicist and mathematician, advanced the three laws of motion to describe planetary motion and answer WHY planets move the way they do. Sir Isaac Newton (1643–1727), an English physicist and mathematician, advanced the three laws of motion to describe planetary motion and answer WHY planets move the way they do. I can calculate the motion of heavenly bodies, but not the madness of people To every action there is always opposed an equal reaction. I can’t wait to brush my glorious locks…