| Question |
 |
|
| Answer |
 |
|
| Showed that planets and moons stay in orbit due to gravity |
Sir Isaac Newton |
| was one of the first perons to use a telescope to observe celestial bodies |
Galileo Gallilei |
| developed a theory of a sun-centered universe |
Copernicus |
| stated that planets move in elliptical orbits around the sun |
Johannes Kepler |
| used a mural quadrant to measure the positions of planets and stars |
Tycho Brahe |
| developed a theory of an Earth-centered universe in 140 CE |
Ptolemy |
| proved the existenc ot galaxies other than the Milky Way |
Edwin Hubble |
| the time required for the Earth to orbit once around the sun |
Year |
| roughly the amound of time required for the moon to orbit once around the Earth |
Month |
| the time required for the earth to rotate once on its axis |
Day |