| The
Shapley-Curtis Debate: 1920 |
|
|
|
|
|
|
|
|
|
| • | Are spiral nebulae really other |
|||||||
| galaxies, or just swirling clouds of |
||||||||
| gas and dust within our own |
||||||||
| galaxy? |
||||||||
| • | Many spiral galaxies had much |
|||||||
| larger radial velocities than other |
||||||||
| objects within our own galaxy |
||||||||
|
|
|
|
|
|
|
|
|
|
| • | Answered by new observations: |
||||||||
| • | In 1923/4 Edwin Hubble photographed and
identified Cepheids in the |
||||||||
| Andromeda Galaxy: |
|||||||||
| – | Distance to Cepheids cleared showed Andromeda was
outside our own |
||||||||
| galaxy |
|||||||||
