| A | B |
|---|
| telescope | A device built to observe distant objescts by makingthem appear closer |
| elecotromagnetic radiation | Energy that travels through space in the form of waves |
| visible light | Electromagnentic radiation that can be seen with the unaided eye |
| wavelength | The distance between the crest of one wave and the crest of the next wave |
| spectrum | The range of wavelengths of the electromagnetic waves |
| optical telescope | A telescope that uses lenses or mirrors to collect and focaus visible light |
| reflecting telescope | A telescpe that uses a curved mirror to collect and focus light |
| convex lens | A piece of tranparent glass curved so that the middle is thicker than the edges |
| refrating telescope | A telescope that uses convex lenses to gather and focus light |
| radio telescope | A device used to detect radio waves from objects in space |
| observatory | A building that contains one or more telescopes |
| constellation | An imaginary pattern of stars in the sky |
| spectrograph | An instrument that seperates light into colors and makes an image of the resulting spectrum |
| apperent brightness | The brightness of a star as seen from Earth |
| absolute brightness | The brightness a star would have if it were at a standard distance from Earth |
| light-year | The distance that light travels in one year, about 9.5million million kilometers |
| parallax | The apparent change in position of an object when seen from different places |
| Hertzsprung-Russell diagram | A graph relating the surface temperatures and absolute brightness of stars |
| main sequence | A diagonal area on an H-R diagram that includes more than 90 percent of all stars |
| nebula | A large cloud of gas and dust in space,spread out in an immense volume |
| protostar | A contracting cloud of gas and dust with enough mass to from to form a star |
| white dwarf | The blue-white hot ore of a star that is legt behind after its outer layers have expanded and drefted out into space |
| supernova | The brilliant explosion of a dying supergiant star |
| neutron star | The small, dense remains of a high-mass star after a supernova |
| pulsar | A rapidly spinning neutron star that produces radio waves |
| black hole | An object whose gravity is so strong that nothing, not even light, can escape |
| binary star | A star system with two stars |
| eclipsing binary | A binary star system in which one star periodically blocks the light from the other |
| open cluster | A star cluster thar has a loose, disorganized appearance and contains no more than a few thousand stars |
| globular cluster | A large, round, densely-packed grouping of older stars |
| galaxy | A huge group of single stars, star systems,star clusters, dust, and gas bound together by gravity |
| spiral galaxy | A galaxy with a bulge in the middle and arms thar soiral outward in a pinwheel pattern |
| elliptical galaxy | A galaxy shaped like a round or flattened ba;l, geberally containing only odd stars |
| irregular galaxy | A galaxy that does not have a regular shape |
| quasar | An enormously bright, distant galaxy with a giant black hole at its center |
| universe | All of space and everything in it |
| scientific notation | A mathematical method of writing numbers using powers of ten |
