Across
- 4. apparent change in the movement of a planet through the sky when it is not real; hint: retro+what are on parentportal
- 7. light rays are bent by gravity gravity force that pulls on a mass (typically towards the center of the Earth)
- 10. Tycho Brahe, Johannes Kepler, Henry Cavendish tides related to the moon
- 11. center of black hole
- 12. (universal law of _) Newton's law, every particle attracts every other particle in the universe
Down
- 1. collapsed star with a gravitational force so stupendous that not even light can escape
- 2. laws; planets follow elliptical orbits, planets cover equal area in equal time, period of planet increases as its mean distance from Sun is raised to the 3 / 2 power
- 3. satellite with the same orbital period as the Earth's rotation period
- 5. minimum velocity needed to break free of a gravitational influence of a massive body
- 6. Newton's law, gravitational attraction force between two point masses is inversely proportional to the square of their separation distance
- 8. gravity, strong force, weak force, electromagnetic
- 9. Recollapsing, critical, coasting, accelerating