Geocentric Model Earth Centered Everything in the universe

Geocentric Model • Earth Centered • Everything in the universe orbited around Earth • Supporters : Aristotle, Ptolemy, the catholic church

Heliocentric Model Sun centered Supporters: Copernicus, Galileo, Newton

Aristotle (384 BC) • Ancient Greek philosopher • wrote about several scientific ideas • His ideas were accepted by Western Civilization • Ideas supported by the Catholic Church • Believed the Universe was “Earth-centered” or “Geocentric”

Ptolemy (150 AD) • Roman citizen that lived in Egypt • Worked as an astronomer and a mathematician • Used mathematics to develop models of the structure of the Universe • His model was Earth centered or “Geocentric”

Nicolaus Copernicus 1473 -1543 Religious man who was also an astronomer First astronomer to formulate a Heliocentric model The“Heliocentric” model places the Sun as the center of the Universe. Collected data when he made observations of the sky

Copernicus’ Discoveries 1. Earth moved with a daily motion on its axis (rotation) 2. Also moved with a yearly motion around a stationary sun (revolution) Heliocentric (Greek) Helios = Sun Centric= Center

Scientific Revolution • Copernicus compiled his observations and wrote about his theory • He was reluctant to publish because he did not want to offend the church • His findings began the age of modern astronomy

Johannes Kepler 1571 -1630 Johannes Kepler's Laws of Planetary Motion : Kepler's laws challenged Aristotle and Ptolemy. His studies showed that the Earth moved, in elliptical orbits.

Galileo Galilei 15641642 Made improvements to the telescope which led to better observations of the night sky Galileo’s Model Ptolemy’s Model

With his more powerful telescopes, Galileo began making astronomical discoveries including… mountains and valleys on the moon Sunspots The four largest satellites of Jupiter, now called the Galilean moons image courtesy of NASA

• Beginning in 1610, Galileo began making observations of Venus and its phases. • The observations gave further evidence to support the heliocentric model by Copernicus (100 yrs later). • Galileo wrote AND PUBLISHED a book called the Starry Messenger, which supported the Heliocentric model of the universe. • Making his Heliocentric ideas public upset the Catholic church. Luckily, he was friends with the Pope, and he was only sentenced to house arrest for the rest of his life because of his work.

Sir Isaac Newton 1642 - 1726 Developed laws of motion that helped support Kelpler’s laws Provided further evidence to support the heliocentric model The ban on the heliocentric model was lifted after Newton’s discoveries