1. SPACE SCIENCE UNIT 2 LESSON 1 Historical Modes of the Solar System

2. Solar system – the sun and all of the bodies that orbit it

3. Models of the solar system 1.Heliocentric – the sun is the center of our solar system 2. Geocentric – the earth is the center of our solar system 3. Parallax – The apparent shift in the position of an object when viewed from different locations

4. Aristotle – Greek philosopher 384-322 BCE Geocentric model Parallax

5. Aristarchus – Greek Astronomer and Mathematician 310-230 BCE Heliocentric Not widely accepted Attempted to measure relative distances to the moon and sun

6. Ptolemy – Egyptian Astronomer and Mathematician 100-170 CE Geocentric His book was based observations going back 800 years First detailed model of geocentric model (used for the 14 centuries) Celestial bodies travel at a constant speed Orbits perfect circle “Wheels on Wheels” system

7. Copernicus – Polish Astronomer 1473-1543 Heliocentric Made first detailed model of heliocentric model First step in the modern model Orbits perfect circles “Wheels on Wheels” system

8. Brahe – Danish Astronomer 1546-1601 20 years of observations of the planets

9. Kepler – German Astronomer 1571-1630 Heliocentric Used Brahe’s observations 3 laws of planetary motion – 1. elliptical orbits – 2. closer to the sun the fast planet revolves – 3. Farther from the sun takes longer to orbit

10. Galileo – Italian scientist 1564-1642 Heliocentric Used scientific method Evidence for heliocentric model – Found 4 natural satellites of Jupiter – Found that Venus goes through phases – Not all bodies in space revolve around earth