| A | B |
|---|
| binary stars | member of a double star system |
| constellation | group of stars that form a pattern |
| nova | a star that suddenly increases in brightness in just a few hours or days |
| nebula | a huge cloud of dust and gas between the stars |
| galaxy | huge collection of stars |
| spiral galaxy | a galaxy that is shaped like a pinwheel; one of three types of galaxies |
| elliptical galaxy | a gallaxy that can change shape from spherical to flat; one of three galaxy types |
| spectroscope | an instrument that breaks up light into its characteristic colors |
| spectrum | the band of colors formed when light passes through a prism |
| red shift | a shift toward the red end of the spectrum of a star that is moving away from the earth |
| doppler effect | apparent change in the wave-length of light that occurs when an object is moving toward or away from the Earth |
| big-bang theory | a theory that says the universe began to expand with an explosion of concentrated matter and energy and continues to expand |
| gravity | force of attraction between objects |
| quasar | a star like object (quasi stellar) they give off radio waves and x-rays |
| giant star | star with a diameter about 10 to 100 times as large as the sun |
| supergiant star | star with a diameter up to 1000 times the diameter of the sun; the largest of all stars |
| white dwarf | small dense star |
| neutron star | smallest of all the stars |
| apparent magnitude | brightness of a star as it appears on the Earth |
| absolute magnitude | amount of light a star actually gives off |
| Hertzsprung-Russell diagram | a chart that show the relationship between the absolute magnitude and the surface temperature of stars |
| main sequence star | in the H-R diagram, a star that lies in an area from the upper left corner to the lower right corner |
| parallax | an apparent change in the position of a star due to the change in the Earth's position as the Earth moves around the sun |
| nuclear fusion | combining of two atomic nuclei to produce one larger nucleus, with the release of nuclear energy |
| corona | outermost layer of the sun's atmosphere |
| chromosphere | middle layer of the sun's atmosphere |
| photosphere | innermost layer of the sun's atmosphere |
| core | center of the sun, Earth, or other object |
| prominence | violent storm on the sun that can be seen from the Earth as a huge bright arch or loop of hot gas |
| solar flare | storm on the sun that occurs when thenew moon comes directly between the sun and the Earth |
| solar wind | a continuous stream of high-energy particles released into space from the sun's corona |
| sunspot | dark area on the sun's surface |
| axis | imaginary vertical line through the center of a body around which the body rotates or spins |
| protostar | a new star |
| supernova | a tremendous explosion in which a star breaks apart, releasing energy and newly formed elements |
| pulsar | neutron star that gives off pulses of radio waves |
| black hole | core of a supermassive star that remains after a supernova; has gravity so strong that even light can't escape |
