Space

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Across
  1. 2. a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body
  2. 3. a large bag filled with gas so that it rises in the air
  3. 7. the force that causes something to fall to the ground
  4. 8. physical power which moves something
  5. 9. a gas which is lighter than air
Down
  1. 1. the sudden increased pressure against a vehicle when it travels at near the speed of sound
  2. 4. we need this gas to breathe
  3. 5. a machine which produces power to make a vehicle move
  4. 6. a large piece of material that fills with air and helps the wearer fall slowly to the