Astronomy › Section S · The Milky Way › Topic S.4
The centre of the galaxy
The heart of the Milky Way is hidden behind a wall of dust, yet astronomers have watched individual stars race around it. Their orbits weigh an object of about four million solar masses packed into a space smaller than Mercury's orbit: a supermassive black hole.
In this topic
- A hidden heart
- The radio and X-ray view
- A crowded neighbourhood
- Watching stars orbit
- Worked example: S2 at its closest approach
- How small is it?
- Worked example: the size of the event horizon
- Nobel-winning tests
- A quiet giant
- Common mistakes to avoid
- Key takeaways
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