| A | B |
|---|
| geocentric model | all sky objects revolve around Earth |
| "geo" | Earth |
| "helio" | Sun |
| heliocentric model | solar system objects revolve around sun |
| assumption | something you believe to be true without questioning it |
| model | a human construct to explain how something might work |
| Ancient Greek's ideal shape | circles |
| "backward" motion in the sky | retrograde motion |
| epicycles | circles around circles |
| celestial spheres | Ancient Greek model of sky objects on crystalline spheres |
| prime mover | outer celestial sphere that made other spheres move |
| rotation | spining of an object about its axis |
| revolution | orbitting of one object around another object |
| paradigm shift | significant change in one's thinking |
| Occam's razor | the idea that the theory with the fewest assumptions is preferred or best |
| Claudius Ptolemy | Introduced epicycles into the geocentric model |
| Nicholaus Copernicus | Wrote one of first detailed explanations of heliocentric model |
| Galileo Galilei | Was forced to retract (take back) his support for the heliocentric model or else he'd be jailed |
| Tycho Brahe | His detailed observations were used by Kepler to mathematically explain the orbits of planets |
| Johannes Kepler | Explained planets orbits mathematically |
