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Astronomy #3
| Term | Definition |
|---|---|
| constellation | imaginary patterns formed from groups of stars |
| parallax | the apparent change in the position of an object when seen from different places |
| light-year | the distance light travels in one year; 9.5 million million kilometers (9.5 trillion km) |
| Hertzsprung-Russell diagram | graph showing the relationship between a star's temperature and its brightness |
| solar nebula | large cloud of gas and dust such as the one that formed our solar system |
| spiral galaxy | galaxy with a bulge in the center and arms that spiral outward like a pinwheel |
| elliptical galaxy | galaxy shaped like a round or flattened ball, generally containing only old stars |
| binary star | star systems that have two, or double, stars |
| quasar | extremely bright, distant galaxy with a giant black hole at its center |
| refracting telescope | uses convex lenses to gather and focus light |
| reflecting telescope | uses a curved mirror to collect and focus light |
| radio telescope | device used to detect radio waves from objects in space |
| optical telescope | uses lenses and mirrors to collect and focus visible light |
| nebula | large cloud of gas and dust spread out in an immense volume |
| protostar | contracting cloud of dust and gas with enough mass to form a star |
| white dwarf | blue-white hot core of a star after the outer layers have expanded and drifted into space |
| supernova | the brilliant explosion occurring of a dying supergiant star |
| neutron star | the remains of a dense, high-mass star after a supernova |
| pulsar | rapidly spinning neutron star that produces radio waves |
| black hole | an object with gravity so strong that nothing, including light, can escape |