Astronomy Section 1
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Created by:
caitlynchausow on July 1, 2012
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23 terms
Terms | Definitions |
|---|---|
 Parallax | the apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes |
| Geocentric Model | earth stationary at the center of the universe |
| Heliocentric Model | sun stationary at the center of the universe |
| Aristotle | first to suggest the geocentric model |
| Ptolemy | noticed that planets speed-up, slow-down, and even reverse direction of motion (retrograde motion). Model contained epicycles. |
| Deferent | a large circle encircling Earth, on which an epicycle moves |
| Epicycle | each plant rides on a small _____ whose center in turn rides on a larger circle called the deferent |
| Supported the Geocentric Model | stars don't seem to show any parallax |
| Supported the Geocentric Model | we don't feel as though the Earth moves |
| Supported the Geocentric Model | objects fall toward Earth, not the sun |
| Copernican | reintroduced the Heliocentric model |
| Copernican Model | model accounted for retrograde motion. Lacked uniform circular motion (same speed all along the circle) |
| Tycho Brahe | made own instruments to observe the universe. Believed that the sun and moon orbited the Earth and then all the other planets and stars orbited around the sun |
| Kepler | said that orbits are ellipses not circles |
| Kepler's 1st Law | planetary orbits are ellipses, sun at one focus |
| Perihellon | closest to sun |
| Aphellon | farthest from sun |
| Kepler's 2nd Law | draw imaginary line from planet to sun. sweeps over equal area in equal time. Distance between the planet and the sun changes as the planet orbits the sun. |
| Kepler's 3rd Law | planet's orbital period squared is proportional to cube of its average distance from sun |
| Galileo | confirmed Copernicans ideas with three major results from use of telescope |
| Galileo's Finding that Contradicts Ptolemy Model | phases of Venus: crescent when close to Earth, gibbous when furthest away. Concluded Venus revolves around the sun. |
| Aristarchu | 1st suggested heliocentric model |
| Known Planets | Mercury, Venus, Mars, Jupiter, Saturn (sun and moon) |
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