1. Measuring Distance to Stars
Very difficult!
Astronomers have developed methods of determining stellar distances.

2.  Parallax (most basic way to measure star distance)
• Slight shift of apparent position of a star due to the orbital motion of Earth (determined from photographs)
* Nearest stars have largest angles; distant stars are too small to measure.

3.  Variable Stars (stars may fluctuate in brightness)
• Cepheid Variable: varies in brightness at a measureable interval
Nova - explosively increases in brightness (sudden change).
Who cares?
Figure 6: pg. 705 Images of a Nova Taken 2 Months Apart, shows the decrease in brightness that follows a nova flare-up.