| A | B |
|---|
| star | body of gases that gives off a tremendous amount of radiant energy in the form of light & heat |
| spectroscope | instrument that splits white light into a band of colors |
| circumpolar | describing any star that is always visible in the night sky & from the Noarthern Hemisphere can be seen circling Polaris |
| red shift | apparent lengthening of the light waves emitted by a star moving away from Earth |
| blue shift | apparent shortening of the light waves emitted by a star moving towards Earth |
| doppler effect | apparent shift in the wavelength of a sound wave or light wave emitted by a source moving away from or toward an observer |
| big bang theory | the universe began with an explosion of a hot, dense sphere billions of years ago & is still expanding |
| background radiation | low levels of energy evenly distributed throughout the universe |
| light year | distance that light travels in one year, about 9.5 trillion km |
| parallax | method of determining the distance from Earth to a star based on the shift in the apparent position of the star when viewed from different angles |
| apparent magnitude | brightness of a star as it appears from Earth |
| absolute magnitude | brightness of a star as it would apppear if located 32.6 light years from Earth |
| H-R diagram | graph showing the relationship of the surface temperature & absolute magnitude of a star |
| main sequence stars | star with characteristics that places it within a band running through the middle of the H-R diagram |
| red giant | very large, cool, bright star |
| white dwarf | small, hot, dim star |
| nebula | cloud of gas & dust in space; first stage in the development of a star |
| protostar | center of a shrinking spinning nebula; second stage in the development of a star |
| nuclear fusion | combination of the nuclei of small atoms to form a larger nucleus |
| nova | white dwarf star that explodes as it cools, temporarily becoming thousands of times brighter |
| supernova | star that blows apart with a tremendous explosion |
| neutron star | collapsed core of a supernova consisting of a small, extremely dense ball of neutrons |
| black hole | hole in space with a gravity so great that not even light can escape, formed by the collapse of a very large supernova |
| galaxy | large scale group of stars |
| normal spiral | galaxy with a center of bright stars & flattened arms that spiral around it |
| barred spiral | galaxy with a bar of stars at the nucleus with flattened arms spiraling around it |
| elliptical | galaxy with a nearly spherical to flattened disk shape |
| irregular | galaxy with no particular shape |
| globular cluster | spherically shaped group of hundreds of stars located around the core of the Milky Way Galaxy |
| open cluster | loosely shaped group of hundreds of stars |
| multiple star system | group of stars in which two stars may revolve around a common center with other stars revolving around them |
| binary star | pair of stars that revolve around each other |
| refracting telescope | uses lenses to bend light as one observes the night sky |
| reflecting telescope | uses mirrors & a lens to reflect the light as one observes the universe |
| eyepiece | smaller lens used as a magnifier in a telescope |
| objective | larger mirror or lens in a telescope that collects the light |
| radio telescope | used to collect radio waves rather than light to explore the universe |
| Hubble Space Telescope | large telescope orbiting Earth that can see deep into the universe |
| celestrial sphere | imaginary ceiling of the universe formed by a big ball with Earth at its center |
| azimuth | distance or angle across the horizon measured from due North |
| zenith | directly above head in celestial sphere |
| declination | angle above the horizon in celestial sphere |
| ecliptic | apparent path of the sun through the Milky Way |
| astronomy | the study of the universe beyond Earth |
| constellation | pattern of stars |
