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Astronomy Chp.3
Galaxies and Stars
| Term | Definition |
|---|---|
| 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 distance between the crest of one wave and the crest of the next. |
| spectrum | the range of wavelengths of electro magnetic 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 edges. |
| reflecting telescope | a telescope that uses one or more mirrors to gather light. |
| 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 percent of all stars. |
| pulsar | a neutron star that produces radio waves. |
| nebula | a large abount 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 super giant star. |
| neutron star | a tiny star that remains after a supernova explosion. |
| 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 with little to not gas and dust. |
| 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. |
Created by:
melaniebird
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