Space

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Across
  1. 2. The first artificial satellite to orbit Earth
  2. 4. A natural satellite of a planet
  3. 5. A large explosion of a star
  4. 7. The smallest planet in our solar system
  5. 8. A large cloud of gas and dust in space
Down
  1. 1. The largest moon of Saturn
  2. 3. The measure of the amount of matter in an object
  3. 4. The fourth planet from the sun, known as the red planet
  4. 6. A scientist who studies celestial objects