Space Puzzle

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Across
  1. 4. Scientist who first realized satellites can be launched into space
  2. 6. The point on the sky directly below your feet
  3. 7. milkyway is this type of galaxy
  4. 8. Nation that launched first artificial satellite
  5. 9. when energy from blackhole outshines the surrounding galaxy
  6. 11. stars that never rise or set
  7. 12. type of rock that gives moon its characteristic light color and is of low density
  8. 13. this mission detected water on Moon
  9. 15. first space station (albeit temporary)
  10. 16. first space probe to take close up images of a comet
  11. 18. satellites are launched using
  12. 19. Maximum number of astronauts ISS can hold
Down
  1. 1. when a satellite has same period of orbit as Earth's rotation
  2. 2. CEO of Mars One
  3. 3. the motion in which mars moved that proved geocentric theory wrong
  4. 5. evolution of stars diagram
  5. 8. size of star can be determined by this law
  6. 10. Zero g airplane
  7. 14. time of the day when waning crescent moon is highest in the sky
  8. 17. Astronauts of this mission were the first to escape Earth's gravity