Great astronomers, astrophysicists, and leaders of the science world, like Aristarchus, Claudius Ptolemy, Hipparchus, Nicolaus Copernicus, Pythagoras, Johannes Kepler, Cassini, Sir Isaac Newton, Joseph Fraunhofer, Annie Canon, Albert Einstein, Edwin Hubble, and Stephen Hawking, emerged with their views and new theories regarding the unknown world around us.