Space

12345678910111213141516171819202122
Across
  1. 1. a comet that is seen every ~76-80 years
  2. 4. a satellite that orbits Earth every 24 hours
  3. 5. comets were used in lecture to describe which of kepler's laws
  4. 8. the primary constituent of comets
  5. 9. a physics teacher
  6. 10. created three laws of planetary motions
  7. 13. a satellite that can be seen in the same location in the sky at all times
  8. 14. the structure of Earth's core
  9. 18. unable to escape from black holes
  10. 19. when a star in the sky has brightness that varies over time
  11. 20. created three laws of motion
  12. 21. all planetary orbits form this shape
Down
  1. 2. an astronomical object that Bruce Willis blew up in 1998
  2. 3. the director of 2001:A Space Odyssey
  3. 6. determined the "G" constant
  4. 7. the period of earth's revolution around the sun
  5. 11. the surface of a black hole
  6. 12. the period of earth's rotation upon its axis
  7. 15. name of locations in a two body orbit of relative gravitational stability
  8. 16. an object that orbits the Earth at an altitude of 400km
  9. 17. a comet with a very long period, last seen in 1997-1998
  10. 22. the radius of a black hole