STELLAR CROSSWORD

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Across
  1. 4. Variant of an element with different numbers of neutrons.
  2. 5. How bright an object like a star appears from Earth.
  3. 8. Particle with a negative charge in an atom.
  4. 10. Measure of how hot or cold something is.
  5. 11. The element formed from hydrogen in stars, symbol He.
  6. 12. Fundamental particle that makes up protons and neutrons.
  7. 13. Fundamental substances that make up matter.
  8. 14. The particle with a positive charge in an atom.
  9. 15. Particle with no charge in the nucleus.
Down
  1. 1. The primary fuel of stars, symbol H.
  2. 2. A very young star in the early formation stage.
  3. 3. The initial cosmic explosion that created the universe.
  4. 6. A cloud of gas and dust in space, often where stars are born.
  5. 7. The total distance around a circle or sphere.
  6. 9. The center of an atom containing protons and neutrons.