| Term |
Definition |
| star | a large celestial body that is composed of gas and that emits light |
| Doppler effect | an observed change in the frequency of a wave when the source or observer is moving |
| light-year | the distance that light travels in one year |
| parallax | an apparent shift in the position of an object when viewed from different locations |
| apparent magnitude | the brightness of a star as seen from the Earth |
| absolute magnitude | the brightness that a star would have at a distance of 32.6 light-years from Earth |
| dark-line spectra | another name for absorption spectra |
| absorption spectra | spectra composed of individual lines at specific frequencies characteristic of the gas |
| emmission spectra | a spectrum consisting of a series of bright lines against a dark background |
| continuous spectra | spectrum formed from white light contains all colors, or frequencies |
| bright-line spectra | another name for emmission spectra |
| Sol | the Latin name of our sun |
| hydrogen | most-common element in stars |
| helium | second most-common element in stars |
| apparent motion of stars | motion visible to the unaided eye, caused by the movement of Earth |
| circumpolar stars | stars that are always visible in the night sky |
| red-shift | wavelength distortion caused by a star moving AWAY from Earth |
| blue-shift | wavelength distortion caused by a star moving TOWARD Earth |
| spectrograph | instrument used to separate light into its different colors or wavelengths |
| absorption spectra | the kind of spectra produced by stars when observed by astronomers |
| O-blue | class and color of hottest stars |
| M-red | class and color of coolest stars |
| OBAFGKM | the spectral classes, in order from hottest to coolest |
| G-yellow | official class and color of the sun |
| circumpolar motion | type of motion where stars appear to revolve around the North Star |
| circumpolar, constellation shift, parallax | What are the three apparant types of stellar motion? |
| rotation, revolution (binary), and toward/away from Earth | What are the three actual motions of stars? |
| parallax | Scientists use this apparent motion to calculate the distance of stars that are within 1,000 light-years from Earth |
| emmission spectra | the type of spectra we observed in the light-tubes lab |
| the gasses the star is made of | What does a star's spectrum tell us about the star? |
