|
| Galaxies |
 |
1. | Why can't we use middle or lower main sequence stars like the Sun or red dwarfs as reliable tracers of spiral structure? |
|
2. | Spiral galaxies contain many red stars, yet the most prominent color for most is blue. Why? |
 |
3. | How can the following two statements be true: two-thirds of all galaxies observed are spirals but most galaxies are faint ellipticals? |
|
4. | Which are more common: spirals or irregular galaxies? |
|
5. | What is the difference between a globular cluster and a dwarf elliptical galaxy? |
|
6. | Andromeda is predicted to collide with the Milky Way in about 3 billion years. Doesn't that contradict the Hubble Law since if Andromeda is flying away it cannot collide with us? |
|
7. | Are the soap bubbles between the voids empty? |
 |
8. | In the section on examples of spiral galaxies an image is shown of the spiral galaxy ESO 269-57. It's Doppler shift indicates a velocity of recession of 3100 km/s. What is its distance by the Hubble law? Its angular size at that distance is about 4 arc minutes. What is its approximate diameter in kilometers? |