1. Star
Properties!!

2. Constellation
A. A grouping of stars (ex. Big Dipper) named after animals, mythological creatures, and everyday objects.

3. 4. Constellation. - Today, there are 88
4. Constellation - Today, there are Some constellations you can see year-round, others only in specific seasons.

4. Clusters of Stars
Star Cluster- A group of stars that is gravitationally bound to each other- they interact with each other.
Binary Stars- two stars that orbit around a common center of mass, and are very close to each other.

5. Stellar Distances
A. Light year - the distance light travels in a year - (it has nothing to do with time) It is 9,500,000,000,000 km Used to show distance to stars

6. Stellar Distances –
B. Parallax - the METHOD used to determine the distance to stars The star appears to move because Earth is moving Scientists can look at the angle of apparent movement to determine how far away the star is.

7. Star Color vs. Star Temperature
A. Hot Stars- stars that are 30, K or hotter are blue.
Medium Stars- stars in the middle range appear yellow.
Cool Stars- stars in the 4,000 K or less range are red.

8. 6. Star Color vs. Star Temperature

9. Hertzsprung-Russell Diagram
A. Y-axis is absolute magnitude
B. X-axis is the temperature of star

10. Hertzsprung-Russell Diagram
C. Main Sequence Stars
- Stars on a curve that runs diagonally through the graph
- 90% of all stars are main sequence.
- Hot and bright stars to cool and dim stars

11. The Hertzsprung-Russell Diagram

12. Hertzsprung-Russell Diagram
D. White Dwarf
- Small, dim, and hot
- Few are White Dwarfs
E. Red Giants
- Large, bright and cool
- Few are Red Giants

13. The Hertzsprung-Russell Diagram

14. Hertzsprung-Russell Diagram
F. Our sun is average in size and temperature (main sequence star)

15. Star Composition
Most stars are about 73% hydrogen and 25% helium!!