| Term | Definition |
|---|
| telescope | device that makes distant objects appear to be closer |
| electromagnetic radiation | energy that can travel through space in the form of waves |
| visible light | light you can see |
| wavelength | the distance between the crest of one wave and the crest of the next wave |
| spectrum | a range of different colors with different wave lengths that you see coming out of a prism with light shone through it |
| optical telescope | a telescope that uses lenses or mirrors to collect and focus visible light |
| refracting telescope | uses convex lenses to gather and focus light |
| convex lens | piece of transparent glass curved so that the middle is thicker than the edges |
| reflecting telescope | uses a curved mirror to collect and focus light |
| radio telescope | devices used to detect radio waves from objects in space |
| observatory | building that contains one more telescopes |
| constellation | imaginary patterns of stars |
| spectrograph | device that breaks light into colors and produces an image of the resulting spectrum |
| apparent brightness | a star's brightness seen from earth |
| absolute brightness | a star's brightness the star would have if it were at a standard distance from earth |
| light-year | distance that light travels in one year |
| parallax | apparent change in position of an object when you look at it from different places |
| Hertzsprung-Russell Diagram | the graph astronomers made to find out if the temperature and absolute brightness of a star are related |
| main sequence | where most of the stars in the H-R diagram are, the diagonal area |
| nebula | large cloud of gas and dust spread out in an immense volume |
| protostar | contracting cloud of gas and dust with enough mass to form a star |
| white dwarf | blue-white core of the star that is left behind that cools |
| supernova | the explosion when a star runs out of fuel |
| neutron star | remains of high-mass stars |
| pulsar | spinning neutron stars, short for pulsating radio sources |
| black hole | an object with gravity so strong that nothing, not even light can escape |
| binary star | star systems that have two stars |
| eclipsing binary | system in which one star periodically blocks the light from another |
| open cluster | have a loose, disorganized appearance and contain no more than a few thousand stars |
| globular cluster | large groupings of older stars |
| galaxy | huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity |
| spiral galaxy | galaxy with a bulge in the middle and arms that spiral outward like pinwheels |
| elliptical galaxy | galaxies that look like round or flattened balls |
| irregular galaxy | galaxies without regular shapes |
| quasar | active young galaxies with giant black holes in the middle |
| universe | all of space and everything in it |
| scientific notation | uses powers of ten to write very large or very small numbers in shorter form |
| big bang | what the universe exploding is called |
| Hubble's Law | states that the father away a galaxy is, the faster it is moving away from us |
| cosmic background radiation | leftover thermal energy from the big bang |
| solar nebula | a large cloud of gas and dust such as the one that formed solar system |
| planetesimal | small asteroid like bodies |
| dark matter | matter that does not give off electromagnetic radiation |
| dark energy | a mysterious new force that astronomers infer is causing the expansion of the universe to accelerate |
Combine with other sets
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