Across
- 3. a place in space where gravity pulls so much that even light cannot escape
- 5. unit distance measurement
- 8. whether or not the density of the universe is above or below this number determines the fate of the universe
- 9. gravitational force, electromagnetic force, nuclear strong force, weak force
- 10. when a light source moves away from you and the light it emits shifts toward the red spectrum
Down
- 1. systems of dust, gas, dark matter and a million to a trillion stars held together by gravity
- 2. the observed apparent change in the position of an object resulting from a change in the position of the observer
- 4. an instrument for measuring the intensity of lights
- 6. unit of thermodynamic measurement
- 7. a mysterious energy or force that repels objects and the reason the expansion of the universe is speeding up
- 8. the study of nature and the evolution of the universe