| A | B |
|---|
| constellation | A pattern of stars in the sky |
| absolute magnitude | The brightness of a star if it were a standard distance from Earth |
| apparent magnitude | The brightness of a star as seen from Earth |
| big bang | The initial explosion that resulted in the formation and expansion of the universe |
| binary star | A star system that contains two stars |
| black hole | The remains of an extremely massive star pulled into a small volume by the force of gravity |
| convex lens | A piece of transparent glass curved so that the middle is thicker than the edges |
| eclipsing binary | A star system in which one star periodically blocks the light form another |
| electromagnetic radiation | Energy that can travel through space |
| elliptical galaxy | A galaxy shaped like a flattened ball, containing old stars |
| galaxy | A giant structure that contains hundreds of billions of stars |
| giant star | A very large star, much larger than the Sun |
| Hertzsprung-Russell diagram | A graph that relates the temperature and brightness or stars- shows that main sequence stars increasing in brightness also increase in temperature |
| irregular galaxy | A galaxy that does not have a regular shape |
| light-year | The distance that light travels in one year |
| main sequence | A diagonal area on the Hertzsprung-Russell diagram that includes more than 90 percent of all stars, including our Sun |
| nebula | A large amount of gas and dust in space, spread out in an immense volume |
| neutron star | The remains of a supernova explosion that has condensed to a very tiny star- 1 teaspoon has more mass than Earth! |
| observatory | A building containing one or more telescopes- usually located in mountains or areas with very clear sky |
| parallax | The apparent change in position of an object when seen from diferent places. |
| protostar | A contracting cloud of gas and dust; the earliest stage of a star's life |
| pulsar | A neutron star that produces radio waves |
| quasar | A distant galaxy with a black hole at its center |
| radio telescope | A device used to detect radio waves from objects in space |
| reflecting telescope | A telescope that uses one or more mirrors to gather light |
| refracting telescope | A telescope that uses convex lenses to gather and focus light |
| spectrograph | An instrument that seperates light into colors and photographs the resulting spectrum |
| spectrum | The range of wavelengths of electromagnetic waves |
| spiral galaxy | A galaxy whose arms curve outward in a pinwheel pattern |
| supernova | The explosion of a dying giant or supergiant star |
| universe | All of space and everything in it |
| visible light | Electromagnetic radiation that can be seen with the unaided eye |
| wavelength | The horizontal distance between two wave crests that distinguish one type of electromagnetic wave from another |
| white dwarf | The remaining hot core of a star after its outer layers have expanded and drifted out into space |
