| A | B |
|---|
| nebula | gas and dust |
| protostar | forms from nebula |
| heliocentric | sun is center of solar system |
| geocentric | earth is center of solar system |
| Kepler | discovers elliptical orbits |
| Copernicus | heliocentric view of solar system |
| Ptolemy | geocentric view of universe |
| refracting telescope | uses mirrors to gather light |
| spiral galaxy | shaped like a pinwheel |
| elliptical galaxy | shaped like a flattened oval |
| Big Bang Theory | explains origin of universe |
| classifiction of stars | temperature, brightness, and size |
| corona | outermost layer of sun |
| nuclear fusion | produces energy in sun and other stars |
| hydrogen | element makes up 60% of stars |
| black hole | follows supernova of giant star |
| white dwarf | follows nova of medium sized star |
| protostar | early stage of star, formed from nebula |
| Hertzsprung-Russell diagram | compares temperature and brightness of stars |
| refracting telescope | uses lenses to gather visible light |
