1. Ch.20 The Solar System Section 1: Observing the Solar System

2. Section 1 Earth at the Center – Greek Observations – Geocentric – In a geocentric system, Earth is at the center of the revolving planets and stars – Ptolemy’s Model

3. Section 1 Sun at the Center – Heliocentric (sun centered) – In a heliocentric system, Earth and the other planets revolve around the sun – The Copernican Revolution Copernicus was able to work out the arrangement of the known planets and how they move around the sun

4. Section 1 Sun at the Center – Galileo’s Evidence Galileo used the newly invented telescope to make discoveries that supported the heliocentric model – Tycho Brahe’s Observations – Kepler’s Calculations Ellipse Kepler found that the orbit of each planet is an ellipse

5. Section 1 Modern Discoveries – Today we know that the solar system consists of the sun, the planets and their moons, and several kinds of smaller objects that revolve around the sun – What six planets were known to the ancient Greeks?