| A | B |
|---|
| Galaxy | a giant, flat structure that contains billions of stars. |
| Universe | All of space and everything in it. |
| Empty Space | Most of the universe is made up of this. |
| Light-year | DISTANCE that light travels in one year. |
| Parallax | The apparent change in position of an object when you look at it from different places. |
| Size, brightness, and temperature | The characteristics used to classify stars. |
| Apparent magnitude | A star's brightness as seen from Earth. |
| Absolute magnitude | The brightness a star would have if it were a standard distance from Earth. |
