| A | B |
|---|
| spectroscope | Instrument that breaks up light into its characteristic colors. |
| spectrum | Band of colors formed when light passes through a prism |
| red shift | Shift toward the red end of the spectrum of a star that is moving away from the earth |
| Doppler effect | Apparent change in the wavelength of light that occurs when an object is moving towards or away from earth |
| big-bang theory | Theory that states that the universe began to expand with an explosion of concentrated matter and energy and has been expanding ever since |
| gravity | Force of attraction between objects |
| quasar | quasi-stellar radio source; distant object that gives off mainly radio waves and X-rays |
| open universe | A universe that continues to expand. |
| closed universe | The reverse of the big-bang; where the matter of the universe will pack itself back into a small area that can be no larger then the period at the end of this sentence. And then will again explode into a new universe. |
