By Maya & Carlee

Content

 Introduction  Plolemy’s Theory  Copernicus’ Theory  Galileo’s Theory  Kepler’s Theory

Introduction

Ptolemy 100-170 A.D

Nicolaus Copernicus 1473-1543 Johannes Kepler 1571-1630 Galileo Galilei 1564-1642 Our solar system includes the sun, eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Venus and Neptune) moons, satellites and dwarf planets.

Ptolemy’s Theory

Ptolemy (100-170 A.D) lived in Egypt as a mathematician, geographer and an astrologist whose solar system theories were thought to be true until the mid 1500. Little is known about Ptolemy’s life, other than that he was born in Egypt while it was still a Roman province. Ptolemy’s theory was that the Earth was the center of the universe and everything else moves around or towards the earth’s center. He also believed that the sun, moon and stars all moved around the earth at different speeds. His theory is known as the Ptolemaic system or the Geocentric Theory. Ptolemy’s theory was accepted in the church because the earth was the center, or most important. His theory was used for many years.

Copernicus’ Theory

Nicolaus Copernicus (1473-1543) lived in Poland as a astrologist. He is considered the founder of modern day astronomy because of his Heliocentric Theory which was a sun-centered universe, a revolutionary idea. He stated that the earth was a part of the track of planets, and believed the earth to be the third planet from the sun. He also said that the earth revolved yearly around the sun as other planets do, and rotates on an axis daily. He published a book of his ideas which was soon banned by the church until the 1800’s when his ideas had already been furthered by other astrologists.

Galileo’s Theory

Galileo Galilei (1564-1642) was an Italian astronomer who built his first telescope in 1609 and started his observations. He published his first results the year later which described the moon, the moons of Jupiter and many new stars. He later confirmed that the sun rotates and that all the planets rotate around it. However, he thought that planets moved around the sun in circular orbits which was later proved incorrect by Kepler. Galileo worked at confirming the theories of Copernicus, which the church had banished. He got permission to continue with his research, so long as nothing was published. In 1632, Galileo published a book that stated the Heliocentric Theory was correct, and the church charged him with heresy and forced him to say his findings were wrong and was imprisoned.

Kepler’s Theory

Johannes Kepler (1571-1630) was born in Germany and lived as a astronomer adding to Copernicus’ theory. Kepler is well known for his three laws of planetary motion; Kepler’s Laws of Motion. Kepler also introduced the relationships between the six known planets. His theories were greatly accepted in the scientific field, but highly disliked by the church.

Kepler’s Laws of Motion 1. All Planets travel in Elliptical Orbits 2. Equal areas are crossed in equal amounts of time 3. There is a relationship between the time span of a planets elliptical orbit and its distance from the sun.

First Law

All planets travel in elliptical (oval shaped) orbits around two focal points, one being the sun and the other empty space.

Second Law

Equal areas are crossed in equal amounts of time.

Third Law

There is a relationship between the time span of a planets elliptical orbit and its distance from the sun.

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