Since the very dawn of humankind, our species has looked out upon the cosmos in awe of the glory of the heavens above. While the spectacular views offered by our night sky haven't changed a great deal over the eons, our understanding of them has. Knowledge of our universe has gradually expanded over the last few thousand years thanks to the efforts of astronomers through the ages. We know what we do about the universe today thanks to the discoveries of all of these astronomers, the ten most important of whom are listed here.