| A | B |
|---|
| an imaginary pattern of stars in the sky | constellation |
| an instrument that separates light into colors and makes an image of the resulting spectrum | spectograph |
| the brightness of a star as seen from Earth | apparent brightness |
| the brightness a star would have if it were at a standard distance from Earth | absolute brightness |
| the distance that light travels in one year, about 9.5 million million kilometers | light-year |
| the apparent change in position of an object when seen from different places | parallax |
| a graph relating the surface temperatures and absolute brightness of stars | Hertzsprung-Russell diagram |
| a diagonal area on an H-R diagram that includes more than 90 percent of all stars | main sequence |
