Space!

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Across
  1. 2. Has two moons, wind, and is called "the red planet"
  2. 9. The name of our galaxy
  3. 10. The combination of hydrogen atoms to form helium and release energy
  4. 14. The smallest planet
  5. 16. Stars are sorted in a graph by brightness and temperature
  6. 18. The reason we have a year (365 days)
  7. 20. Distance that light travels in one year
  8. 22. The small core of a star that is very hot, but also very dim
  9. 24. Stars that are still going through nuclear fusion
  10. 26. Looks like a dirty snowball. Has a tail that always points away from the sun
Down
  1. 1. The brightness of a star
  2. 2. The reason some planets appear blue
  3. 3. The reason we have day and night (24 hours)
  4. 4. The explosion of a massive star that could result in a black hole
  5. 5. A group of millions or billions of stars held together by gravity
  6. 6. Made of rock and orbits the sun in a belt between Mars and Jupiter
  7. 7. A cloud of gas and dust where new stars are formed
  8. 8. Nicknamed "Earth's Twin"
  9. 11. Rocky planets, the inner four
  10. 12. First telescope put into orbit by NASA around earth
  11. 13. The reason some planets appear red
  12. 15. The largest planet
  13. 17. The name of NASA's missions to the moon.
  14. 19. Model of the solar system proposed by Copernicus in which the sun is the center
  15. 21. Giants The outer four planets
  16. 23. Exists in three states and is the reason Earth supports life
  17. 25. The first man-made satellite put into orbit by Russia