| A | B |
|---|
| Spectrum | Rainbow of colors when white light passes through a prism |
| Spectrograph | Instrument used to spread starlight out into its colors |
| Apparent Magnitude | How bright a light looks or appears |
| Absolute Magnitude | The actual brightness of a star |
| Light-year | The distance that light travels in one year |
| Parallax | Apparent shift in the position of an object |
| H-R Diagram | Shows the relationship of surface temperature to absolute magnitude |
| Main Sequence | Diagonal pattern of stars on the H-R diagram |
| White Dwarf | Small hot star near the end of its life |
| Red Giant | Star that expands and cools once it runs out of hydrogen |
| Supernova | Death of a large star by explosion |
| Neutron Star | Star in which all the particles have become neutrons |
| Pulsar | Spinning neutron star that emits rapid pulses of light |
| Black Hole | Object whose gravity is so strong that not even light can escape |
| Galaxy | Large groupings of stars in space |
| Spiral Galaxy | Galaxy that has a nuclear bulge at the center and spiral arms |
| Elliptical Galaxy | Galaxy that has a bright center and very little dust and gas |
| Irregular Galaxy | Galaxy that does not fit into any other class |
| Nebula | Giant clouds of gas and dust in space |
| Open Cluster | Group of stars that forms when large amounts of gas and dust come together |
| Globular Cluster | Group of older stars that looks like a ball of stars |
| Quasar | Star-like source of light and radio waves that is extremely far away |
| Cosmology | Study of the origin and future of the universe |
| Big Bang Theory | Theory that states the universe began with a tremendous explosion |
| Cosmic Background Radiation | Radiation left from the big bang that fills all of space |
