| A | B |
|---|
| CONSTELLATION | A pattern of stars in the sky. |
| VISIBLE LIGHT | Electromagnetic radiation that can be seen with the unaided eye. |
| ELECTROMAGNETIC RADIATION | Energy that travels through space in the form of waves. |
| WAVELENGTH | The horizontal distance between two wave crests or troughs. |
| SPECTRUM | The range of wavelengths of electromagnetic waves. |
| REFRACTING TELESCOPE | A telescope that uses convex lenses to gather and focus light. |
| CONVEX LENS | A piece of transparent glass curved so that the middle is thicker than the edge. |
| REFLECTING TELESCOPE | A telescope that uses one or more mirrors to gather light. |
| RADIO TELESCOPE | A device used to detect radio waves from objects in space. |
| OBSERVATORY | A building that contains one or more telescopes. |
| SPECTROGRAPH | An instrument that separates light into colors and photographs the resulting spectrum. |
| GALAXY | A giant structure that contains hundreds of billions of stars. |
| UNIVERSE | All of space and everything in it. |
| LIGHT-YEAR | The distance that light travels in one year. |
| PARALLAX | The apparent change in position of an object when seen from different places. |
| GIANT STAR | A very large star, much larger than the sun. |
| APPARENT MAGNITUDE | The brightness of a star as seen from Earth. |
| ABSOLUTE MAGNITUDE | The brightness of a star if it were a standard distance from Earth. |
| HERTZSPRUNG-RUSSELL DIAGRAM | A graph relating the temperature and brightness of stars. |
| MAIN SEQUENCE | An area on the Hertzsprung-Russell diagram that runs from the upper left to the lower right and includes more than 90% of all stars. |
| PULSAR | A neutron star that produces radio waves. |
| NEBULA | A large amount of gas and dust in space, spread out in an immense volume. |
| PROTOSTAR | A contracting cloud of gas and dust; the earliest stage of a star's life. |
| WHITE DWARF | The remaining hot core of a star after its outer layers have expanded and drifted out into space. |
| SUPERNOVA | The explosion of a dying giant or supergiant star. |
| BLACK HOLE | The remains of an extremely massive star pulled into a small volume by the force of gravity. |
| QUASAR | A distant galaxy with a black hole at its center. |
| BINARY STAR | A star system that contains two stars. |
| ECLIPSING BINARY | A star system in which one star periodically blocks the light from another. |
| SPIRAL GALAXY | A galaxy whose arms curve outward in a pinwheel pattern. |
| ELLIPTICAL GALAXY | A galaxy shaped like a flattened ball, containing only old stars. |
| IRREGULAR GALAXY | A galaxy that does not have a regular shape. |
| BIG BANG | The initial explosion that resulted in the formation and expansion of the universe. |
