| A | B |
|---|
| astronomy | study of the universe |
| a year | time takes Earth to ORBIT once around sun |
| a day | time takes Earth to ROTATE once on its axis |
| a month | time takes moon to ORBIT once around Earth |
| Ptolemy | thought Earth was center of universe |
| Copernicus | thought Sun was center of universe |
| Brahe | recorded observations of planets which helped future astronomers |
| Kepler | thought planets revolve around sun, made 3 laws of planetary motion |
| Galileo | used telescope |
| Newton | Laws of Gravity |
| Hubble | proved other galaxies exist beyond Milky Way |
