Maths and Space

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Across
  1. 3. Which numerals do we use today?
  2. 4. What is OneRepublic counting?
  3. 6. Biggest planet in Solar System.
  4. 10. Study of space is called...
  5. 13. Numeric system which does not have a symbol for zero.
  6. 14. Oasis have a song entitled 'Champagne __________'.
  7. 15. Surname of the first human to journey into outer space.
  8. 16. Who sings 'I believe in a think called love'?
  9. 18. Taylor Swift has a 'blank ______, baby'
  10. 20. Where is Pythagoras from?
  11. 21. What substance does Earth contain that is found on no other planet in the Solar System in liquid form?
Down
  1. 1. Only number in the English language with the same number of letters as the number itself.
  2. 2. Hugely influential Italian astronomer and physicist. (Hint: Bohemian Rhapsody)
  3. 5. Name of the first artificial Earth satellite.
  4. 7. 3.14159 are the first 6 digits of which irrational number?
  5. 8. This band has a song entitled '2+2=5'
  6. 9. First animal to orbit the Earth.
  7. 11. Model for the birth of the universe.
  8. 12. Which technological advancement is meant to fly according to Nicki Minaj?
  9. 17. 'Space Bound' is a song by which artist?
  10. 19. Which artist makes the profound claim that 'The square root of 69 is 8 somethin'?