Orbital Motion Review

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Across
  1. 5. the fifth planet from the Sun
  2. 9. leading astronomer in Denmark, believed in a combination of heliocentric and geocentric models where Earth is stationary
  3. 11. the apparent motion of a planet moving backward in the sky due to differences in orbital periods
  4. 15. Ptolemy's explanation for retrograde motion
  5. 16. the third planet from the Sun
  6. 17. the point in an orbit when a planet is furthest away from the star
  7. 18. the increase or decrease in velocity of an object
  8. 20. the fourth planet from the Sun
  9. 21. the cube of a planets orbital radius is proportional to the square of the planets period (as you increase distance from the Sun the orbital period increases)
  10. 23. the seventh planet from the Sun
  11. 24. the point in an orbit when a planet is closest to the star
  12. 25. planets travel around the Sun in elliptical orbits with the Sun at one focus of the ellipse
  13. 26. force in astronomy that pulls two objects toward each other
  14. 28. the speed and direction of an object
Down
  1. 1. the time it takes a planet to travel around the Sun
  2. 2. the first planet from the Sun
  3. 3. Ptolemy's model of the universe, with earth at the center
  4. 4. former ninth planet, now a dwarf planet
  5. 6. average distance between the earth and the sun
  6. 7. a planet accelerates as it approaches the Sun and decelerates as it moves farther from the Sun
  7. 8. the eccentricity of a circle
  8. 10. the eighth planet from the Sun
  9. 12. Copernicus's model of the universe, with the sun at the center
  10. 13. Distance light travels in one year
  11. 14. the line that passes from one end to the other in an ellipse and includes both foci
  12. 19. the sixth planet from the Sun
  13. 22. the number that describes the flatness of the ellipse (equal to the distance between the foci divided by the total width of the ellipse)
  14. 27. the second planet from the sun