The Universe part 2

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Across
  1. 2. type of star that alternately increases and decreases in size usually with corresponding changes in brightness.
  2. 3. Greek word gala means.
  3. 7. type of black hole formed when massive stars use up all their fuel and die.
  4. 8. another name for universe.
  5. 10. ____ fusion is the process by which gas clouds get so hot it begins to form a star.
  6. 14. tool that allows the different wavelengths and colors of light to be seen with the human eye.
  7. 17. another type of galaxy other than spiral, irregular, and peculiar.
  8. 18. the phenomenon by means of which bodies having mass are attracted to one another.
  9. 19. celestial objects made out of frozen gases, rock and dust that orbit the Sun.
  10. 20. About 90% of stars are made of this.
  11. 21. natural objects that orbit planets
  12. 23. when the fuel of a smaller star begins to be used up, it is called this. (2 words)
  13. 24. _____ sensing is the science of gathering data on an object or area from a considerable distance.
Down
  1. 1. two stars that appear as one to the naked eye (2 words)
  2. 4. when the largest stars explode, they collapse under the pressure of tremendous gravity and become this. (2 words)
  3. 5. another name for asteroids.
  4. 6. the name of our galaxy (2 words)
  5. 9. the middle-aged, middle-size star in our solar system.
  6. 11. in larger stars nuclear fusion eventually causes this to form in the star.
  7. 12. ____ 1 is the first human-made spacecraft designed to leave our solar system.
  8. 13. a star with planets orbiting around it (2 words)
  9. 15. the donut-shaped zone of no return on a black hole (2 words).
  10. 16. the fourth state of matter
  11. 22. type of matter that cannot be seen but has a gravitational effect on objects nearby.