Across
- 3. makes up 15% of the know universe
- 6. composed of protons, neutrons, and electrons
- 9. in 1933 used dark matter to explain "missing mass"
Down
- 1. made up of clusters of stars and planets
- 2. dark matter may be tiny, sub-atomic particles which aren't a part of "normal" matter at all
- 4. first proposed dark matter in 1932
- 5. makes up 68% of the unknown universe
- 7. make up 27% of the universe
- 8. learn about the Universe by the electromagnetic radiation (or light) that we see from it