Across
- 3. used to find distance to a galaxy
- 6. occurs when light from a distant object passes a nearby massive object
- 8. cloud of turbulent gas
- 10. a flattened cloud of billion stars
- 11. the orbital speed of visible stars
- 13. relation between apparent velocity of recession and distance
- 14. first called quasi-stellar
- 15. invisible stuff in space that has gravity
Down
- 1. contains most of the galaxy's stars
- 2. highly luminous nuclei with peculiar spectra
- 4. to find the mass of the galaxy
- 5. a measurement of distance
- 7. difficult to observe directly
- 9. triggered by a burst of star formation
- 12. contains a thousand or more galaxies