| A | B |
|---|
| cosmology | study of the universe |
| electromagnetic radiation | travel at 300,000 km/s |
| absolute magnitude | brightness when placed 32.6 LY from Earth |
| apparent magnitude | brightness viewed from Earth |
| H-R Diagram | main sequence |
| nebula | cloud of gas and dust |
| Big Bang | explosion billions of years ago |
| pulsar | pulses of radio waves |
| quasar | quasi-stellar radio source |
| galaxies | spiral, elliptical, irregular |
| light year | about 9.5 trillion km |
| black hole | light cannot escape its gravity |
| constellation | patterns in the sky |
| cosmic background radiation | "echo" of the Big Bang |
| Doppler effect | change in wave frequency due to motion |
| giant | large star just beginning to die |
| main sequence | diagonal band on H-R Diagram |
| nova | star with sudden increase in brightness |
| neutron star | dying star that emits neutrons |
| parallax | change in position of object due to motion of observer |
| universe | all celestial objects together |
| white dwarf | small, dim, dying star |
