Universe Structure

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Across
  1. 4. Large balls of gas that generate energy through nuclear fusion.
  2. 7. The smallest galaxies have an _____ shape.
  3. 8. Pluto is now considered a _____.
  4. 10. Planet where all living things can survive.
  5. 11. _____ is about the same size as Earth and is sometimes called the "morning star".
  6. 12. Objects that orbit planets.
  7. 14. Planets outside our solar system.
  8. 15. Smaller, irregular, rocky objects that orbit stars.
  9. 17. The star in our solar system.
  10. 18. This planet has large seas of liquified hydrogen.
  11. 19. _____ has 146 moons.
  12. 20. Our galaxy is called the _____ galaxy.
Down
  1. 1. Planets must _____ a star.
  2. 2. Clusters of billions of stars held together by gravity.
  3. 3. Any of the large bodies that revolve around the Sun in the solar system.
  4. 5. The largest storm in the solar system.
  5. 6. Planet named after the Roman god of the underworld.
  6. 9. Everything, including all of space, time and matter.
  7. 13. Sometimes called dirty snowballs.
  8. 15. Study of all the objects outside the Earth's atmosphere.
  9. 16. The force of attraction responsible for holding planets in orbit.