| A | B |
|---|
| relative motion | It compares motion of one body to motion of another body. |
| red shift | the effect on spectral lines of objects moving away from earth is __ . |
| main sequence | Stars of the ____ have similar chemical composition byt differ in mass. |
| cepheids | ___ are stars that pulse due to the expansion and contraction of outer gases. |
| quasar | A ___ may be the center of a galaxy that formed many years ago. |
| irregular | ___ galaxies contain many stars and great clouds of gas. |
| black hole | A ___ is the final stage in the life cycle of a star |
| white dwarf | A ___ is a star that radiates its internal heat into space and grows dark. |
| absolute magnitude | ____ represents the brightness of a star at a distance of 10 parsecs. |
| eclipsing | A pair of stars that orbit a common point are __ stars. |
| elliptical | ___ galaxies contain little dust and gas but may have trillions of stars. |
| neutron star | In a ____, electrons and protons combine to form very dense matter. |
| apparent magnitude | A star's birght ness we see is __. |
| fusion | ___ is the process by which stars produce and emit energy. |
| emit | send out |
| spiral | The earth is part of a ___ galaxy. |
