1. Stars How do we find out about them?
What would we like to know about stars?
Only clues we get are from the light by which we see the stars.
The major clues are
Brightness
Color

2. Stars What does a star’s brightness tell us?
Take two identical stars
Put one twice as far away as the other
If you compare their brightness, the more distant one will appear four times fainter
This one looks brighter
Eye

3. Stars What does a star’s color tell us?
Temperature!
Reddish star colors indicate a cool star
White or bluish colored stars are hotter

4. Star Colors
Can you see a blue star? An orange one?

5. Stars Surface temperatures of stars
Blue-white
45,000 deg F
White
20,000 deg F
Yellow
11,000 deg F
Orange
7,500 deg F
Red
5,500 deg F