““one does not need experiments to do science. While this claim may sound strange and counterintuitive at first, a moment's reflection will show that it is obviously true: astronomers do not conduct experiments, and yet we think of astronomy as solidly situated within the sciences, not the humanities or the pseudosciences. Why? Because astronomers can carry out the two fundamental activities that, jointly considered, truly characterize a science: systematic observations and the construction and testing of hypotheses.””
