Are we really made of stardust?

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Across
  1. 1. The planet closest to the Sun
  2. 4. The Milky Way is an example of this
  3. 6. The particle inside the nucleus which has no charge
  4. 9. The particle which orbits the nucleus of an atom
  5. 11. The name of the force which repels two protons
  6. 12. The biggest planet in the solar system
  7. 13. The birthplace of stars
Down
  1. 2. A star the size of the Sun becomes this once hydrogen starts running out
  2. 3. The lightest element
  3. 5. The process which occurs in main sequence stars
  4. 7. An object which orbits another object in the solar system
  5. 8. The units of weight
  6. 10. An object so massive not even light can escape