Historical Models of the Universe & Kepler's Laws

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Across
  1. 5. P-squared = a-cubed describes the relationship between a planet's _____ and average_____ to the sun.
  2. 6. Kepler's 2nd Law is known as The Law of ______.
  3. 7. A planet orbits the slowest at this point on its orbit.
  4. 8. Brahe invented astronomical instruments that were the most _______ until the telescope was invented.
  5. 11. An imaginary line sweeping from the sun to a planets orbit creates "slices" which have equal ______ during an equal period of time.
  6. 14. The shape of a planet's orbit.
  7. 15. 9.296 x 10-7th power equals one ______ _____.
  8. 17. The acronym listing the planets from the smallest to largest orbit. (Including Pluto)
  9. 19. Kepler's 1st Law is know as The Law of _____.
  10. 20. A model of the universe with the earth at its center.
  11. 21. The apparent "loop" that a planet makes from the earth's point of view takes place when the earth ______ the other planet
Down
  1. 1. He believed that the universe was made up of 4 elements: earth, air, water and fire
  2. 2. Galileo's powerful telescope allowed him to identify four _____ of Jupiter.
  3. 3. Newton proposed that the force of _________ kept the planets in motion around the sun.
  4. 4. From the earth's point of view, it may appear that a planet's location loops backward and then forward. This is called ________ _______.
  5. 9. Kepler's 3rd Law is known as The Law of ______.
  6. 10. a small circle whose center moves around the circumference of a larger one.
  7. 12. Aristotle proposed a geocentric "spheres within spheres" model containing a 5th element: _______.
  8. 13. Aristarchus was the first to propose a _______ model of the universe.
  9. 16. His model included aspects of both Aristarchus and Ptolemy.
  10. 18. each elliptical orbit has two of these, with the sun placed at one of them.