Gravity Crossword Puzzle

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