1. Week 3 Notes Observing the Solar System
Ch 3, Section 1
p 72 – 77

2. I. EARTH AT THE CENTER
a. Ancient __GREEKS__ watched stars move across the sky. They noticed that the patterns did __NOT__ move. They named theses patterns __CONSTILLATIONS__

3. A. Greek Observations
a. The word __PLANET__ comes from the Greek word meaning __WANDERERS__
b. These planets consist of __MERCURY__, __VENUS__, __MARS__, __JUPITER__, and __SATURN__
c. __GEO__ is the word for Earth
d. __GEOCENTRIC__ is the belief that __EARTH__ is the center of the revolving planets and stars.

4. B. Ptolemy’s Model
a. __PTOLEMY__ thought that the Earth was the __CENTER__ of the Solar System
b. Ptolemy’s model had planets moving on __SMALL__ circles that traveled on bigger __CIRCLES__
c. This model was __INCORRECT__ but it did explain the motion observed in the sky. It was accepted for nearly __1,500__ years.
Show just enough to understand model

5. II. SUN AT THE CENTER a. __HELIOS__ is Greek for __SUN__
In a __HELIOCENTRIC__ system the __SUN__ is the center of the Solar System
A. Copernican Revolution
a. __COPERNICUS__ was able to work out the __ARRANGEMENT__ of the __KNOWN__ planets and how they __MOVED__ around the __SUN__

6. B. Galileo’s Evidence
a. __GALILEO__ used the __TELESCOPE__ to make discoveries that support the __HELIOCENTRIC__ model.
b. Galileo used a telescope to discover __4__ moons revolving around __JUPITER__
c. The motion of the __MOONS__ proved that not everything in the __SKY__ revolves around Earth
d. __VENUS’S__ phases like that of the __MOON__ also proves that the __HELIOCENTRIC__ model is correct
BrainPop: Galileo

7. C. Tycho Brahe’s Observations
a. __BRAHE__ recorded the __POSITIONS__ of the planets without using a __TELESCOPE__
D. Kepler’s Calculations
a. Kepler found out that the __ORBITS__ of the planets were __ELLIPSE__
b. __ELLIPSE__ is an __OVAL__ shape
c. Kepler stated that all __PLANETS__ orbits are __ELLIPSES__ and __NOT__ perfect circles.

8. III. MODERN DISCOVERIES
a. __GALILEO__ knew of Mercury, Venus, Earth, Mars, Jupiter, and Saturn.
b. Since Galileo we found __2__ more planets- Uranus and Neptune, __PLUTO__ which is no longer considered a planet.
c.. __TELESCOPES__ used to be used on Earth only, now you will find them in __SPACE__ for better views of the Solar System .
Heliocentric vs Geocentric: