Puzzle Time...

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Across
  1. 3. the explosion of a star
  2. 6. increase in wavelength causing a shift toward the red end of the electromagnetic spectrum
  3. 7. consists of stars, gas, and dust held together by gravity
  4. 8. the theory explaining the origin of the universe
Down
  1. 1. consists of space,time,matter and energy
  2. 2. it contains our solar system
  3. 4. a celestial body moving in an elliptical orbit around a star
  4. 5. the study of the cosmos/the entire universe