Space

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Across
  1. 3. type of planets made of heavier elements
  2. 5. large enough to become spherical on top of formed layers
  3. 6. when elements break off from larger, more unstable elements. thisbreak can generate energy
  4. 8. a remnant of a proplyd that is not a planet
Down
  1. 1. a larger asteroid that formed layers
  2. 2. a rotating disc with a new, forming star and remaining materials accreting around it (short name)
  3. 4. a spacial body large enough to clear its neighborhood
  4. 7. type of planet made of lighter elements, blasted by solar wind