1. The Universe  Viewing the Night Sky Clear view of the horizon ○ Stay away from ambient light, houses, & trees A good star chart Telescope or binoculars A good imagination  Is that a planet or a star?

2. The Universe  Star Brightness or Magnitude What determines a star’s magnitude? ○ Distance Light year -Distance light will travel in one year -186,000 mi./sec. ○ Size ○ Actual amount of light being emitted

3. The Universe Two classification scales ○ Apparent Magnitude Based on what you see from Earth Table 14.1 (p. 390) Range -Sun: -26 -Human eye limit: +6 -Telescope (a big one): +26

4. The Universe ○ Absolute Magnitude A stars “real brightness” -Luminosity -Standard distance -32.6 ly 1 sec. of parallax shift

5. The Universe  Temperature & Color of stars Range ○ Blue – 30,000 – 80,000 K ○ Yellow – 5,000 – 6,000 K (Sun) ○ Red – 2,000 – 3,500 K Classification based on temperature & color ○ O, B, A, F, G, K, M Spectral type Hertzsprung-Russell Diagram (Fig. 14.8) ○ Absolute magnitude and spectral type ○ Life cycle of a star

6. The Universe  Life Cycle of a Star Proto Star Stage ○ Forms from the gasses of interstellar space H & He Fusion begins ○ Gravitational attraction of particles ○ Temperature & pressure rises

7. The Universe Main Sequence Stage ○ Star continues to grow in mass & brightness ○ Range of spectral type Red Giant Stage ○ Star begins to cool Return to Main Sequence The End ○ Supernova Massive release of energy A star gives back

8. The Universe  Galaxies ○ Milky Way Spiral  The Beginning The Big Bang Proof of an expanding Universe ○ Edwin Hubble ○ Spectral shift Red shift