Astronomy › Section T · Galaxies and quasars › Topic T.1
The discovery of galaxies
A century ago, many astronomers thought the Milky Way was the whole universe. Measuring the distance to one fuzzy spiral in Andromeda showed that it is one galaxy among billions.
In this topic
- Smudges among the stars
- Island universes?
- The Great Debate
- The evidence on each side
- Worked example: the nova argument
- Hubble finds a Cepheid
- Worked example: a Cepheid in Andromeda
- The universe grows
- Galaxies everywhere
- Common mistakes to avoid
- Key takeaways
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