what is your favourite scientific fact?

Question: what is your favourite scientific fact?
- Keywords:
  fact,
  quirky,
  work
Asked by to Dave on 17 Jun 2014. This question was also asked by .
- Dave Jones answered on 17 Jun 2014:
  
  Ok, let’s try this one. If you took all the blood vessels in the human body and laid them end to end, it would reach about 1/4 of the way to the Moon.

Question: what is your favourite scientific fact?