Chapter 6 Lesson 1 Models of the Solar system

What was the Geocentric model? Geocentric Model- The Earth is at the center of the revolving planets and stars Ancient observers noticed that the patterns of the stars didn’t change over time The stars seemed to move, however they stayed in the same position relative to one another Many early observers believed that the Earth was at the center of the universe

Ptolemy’s model Ptolemy- Greek astronomer who further developed the geocentric model. Believed that Earth was at the center of the universe Ptolemy’s model- planets moved in small circles along in bigger circles His model was widely accepted for 1,500 years after Ptolemy

How did the heliocentric model develop? Not everyone agreed the geocentric model Aristarchus developed a model call the heliocentric model In this model the Earth and the planets revolved around the sun This model was not widely accepted However, people did not truly accept that the Earth was the center of the universe

The Copernican revolution Polish astronomer Nicolaus Copernicus further developed the heliocentric model He was able to work out the arrangement of the planets and how they moved around the sun His model would revolutionize astronomy People still needed more evidence

Brahe and kepler Ptolemy and Copernicus both assumed the planets moved in perfect circles Brahe and his assistant Kepler made calculations that figured out the shape of the orbits of the planets Their calculations did not support circular orblts Their calculations determined the planets orbit was an ellipse Ellipse- an oval shape

GALILEO’S EVIDENCE In the 1500s and 1600s most people still believed in the geocentric model Italian scientist Galilei gradually convinced others that the heliocentric model was correct He used a telescope to discover 4 moons around Jupiter This proved everything did not revolve around the Earth His discovery on phases of Venus similar to the moon on Earth also proved that everything did not revolve around the Earth Thus proving the geocentric model must be incorrect