Space

123456789101112131415161718192021
Across
  1. 3. The layer of gases surrounding Earth (9 letters)
  2. 6. Spacecraft that carried astronauts to the Moon (7 letters)
  3. 9. A massive star explosion (9 letters)
  4. 10. Path taken by an object around a star or planet (5 letters)
  5. 11. Closest planet to the Sun (7 letters)
  6. 15. The first artificial satellite sent into space (6 letters)
  7. 16. The galaxy that contains our Solar System (7 letters)
  8. 19. Small rocky body orbiting the Sun (9 letters)
  9. 20. Study of celestial objects and phenomena (10 letters)
  10. 21. The closest star to Earth (3 letters)
Down
  1. 1. Bright ball of burning gases like our Sun (4 letters)
  2. 2. A place where stars are born (6 letters)
  3. 4. A system of millions or billions of stars (6 letters)
  4. 5. Invisible form of energy in the universe (4 letters)
  5. 7. A telescope that orbits Earth (5 letters)
  6. 8. Natural satellite of Earth (4 letters)
  7. 11. The red planet (5 letters)
  8. 12. These icy celestial bodies orbit the Sun (6 letters)
  9. 13. The force that keeps planets in orbit (9 letters)
  10. 14. The largest planet in our solar system (7 letters)
  11. 17. Twinkling objects seen in the night sky (5 letters)
  12. 18. The first human in space (5 letters)