1. Chapter 6 Lesson 1 Models of the Solar system

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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