Space

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Across
  1. 2. This person compiled the 3 Laws of Planetary Motion
  2. 4. According to Kepler's 3rd Law, square of time is proportional to cube of _______
  3. 6. This is tangential to the curved path
  4. 8. The shape of the path of each planet around the Sun
Down
  1. 1. Escape velocity is ______ than orbital velocity
  2. 3. The speed an object needs tobreak free of a plant or moon's gravity well and leave it without propulsion
  3. 5. No matter what type of orbit a satellite is in, mechanical energy is ______
  4. 7. Director of the world's first observatory