1. THE OLD GUYS

2. Astronomers Click on astronomers to guide you through the PowerPoint. All red boxes are links. Use them to guide you!

3. Astronomy Joke

4. Greek Astronomy  The Greek Universe was the solar system  Sun, Moon, Earth and Planets  Greek Scientists include:  Pythagoras  Aristotle  Aristarchus  Eratosthenes  Hipparchus  Ptolemy

5. Astronomy Joke

6. Pythagoras  Life: 582-507 B.C.  Theories:  1st to recognize the shape of the Earth as round  ‘Proof’ As ships sail away the mast is the last to disappear During a lunar eclipse he noticed the edge of the shadow was curved

8. Aristotle  Life: 384-322 B.C.  Theories:  Geocentric Model: the Earth was the center of the universe  ‘proof’  He based his model on 3 points: The Earth doesn’t feel like it’s moving If it were moving there would be a strong, constant wind We would see a stellar parallaxstellar parallax

10. Aristarchus  Life: 310-230 BC  Theory:  Heliocentric Model: Proposed that the planets and the Earth revolved around the Sun, and that the Earth turned on its axis once a day  ‘Proof’  He was also the first to take measurements of the Sun and the Moon

11. The Theory

12. Why Aristarchus was off...

14. Eratosthenes  Life: 275-195 B.C.  Theory  Using basic geometry he is the first to figure the circumference and diameter of the earth with in 5º

15. How?

16. Hipparchus  Life: 190-120 B.C.  Observations:  Compiled a catalog of more than 800 stars, ranking them according to their apparent brightness  Was the first to suggest precession

17. Ptolemy  Life: 90 - 168 AD  Theory:  Was the first to come up with a good working model for a geocentric Universe  Planets moved in circles (which was the perfect form) but added an epicycle on which the planets also moved Saw Retrograde Motion Backward, westward loop traced out by a planet with respect to the fixed stars

20. Mapping Mars As mars is tracked through the night sky, it looks like it back tracks for a few months = epicycle

21. Tracking Mars Movement From earth’s view versus mars, you can see there is an overlap when earth passes mars in our trip around the sun = our year is faster so we pass mars and it looks like mars is going backwards