THE OLD GUYS
Astronomers Click on astronomers to guide you through the PowerPoint. All red boxes are links. Use them to guide you!
Astronomy Joke
Greek Astronomy The Greek Universe was the solar system Sun, Moon, Earth and Planets Greek Scientists include: Pythagoras Aristotle Aristarchus Eratosthenes Hipparchus Ptolemy
Astronomy Joke
Pythagoras Life: 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
Aristotle Life: 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
Aristarchus Life: 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
The Theory
Why Aristarchus was off...
Eratosthenes Life: B.C. Theory Using basic geometry he is the first to figure the circumference and diameter of the earth with in 5º
How?
Hipparchus Life: B.C. Observations: Compiled a catalog of more than 800 stars, ranking them according to their apparent brightness Was the first to suggest precession
Ptolemy Life: 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
Mapping Mars As mars is tracked through the night sky, it looks like it back tracks for a few months = epicycle
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