Physics Puzzle

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Across
  1. 1. /Group of atoms bonded together
  2. 3. /Lots lighter than quarks and nuclei.
  3. 4. /Anything orbiting anything
  4. 6. /Basic unit of a chemical element
  5. 9. /A subatomic particle of about the same mass as a proton but without an electric charge
  6. 12. /Other combinations of Quarks make up?
  7. 13. /Rocks in orbits like planets
  8. 14. /Consists of everything observable
  9. 17. /Gravity of the invisible
  10. 18. /Come from a huge spherical cloud far outside of the Kuiper Belt called the Oort Cloud.
  11. 19. /Our sun is a
Down
  1. 1. /FO (Divided by Area) FI
  2. 2. /Generic name for electrons and their relatives mu and tau, and the associated neutrinos.
  3. 5. /Can never be “proved”
  4. 7. /The Earth
  5. 8. /Small solid object orbiting a sun
  6. 10. /Held together by gluons.
  7. 11. /If it goes around a planet it is
  8. 15. /Groups of millions to billions of stars held together by their mutual gravity
  9. 16. /Force (divided by) Area