For centuries astronomers have trained their gaze on the matter that brightens the universe: the moon, the planets, the stars, and the galaxies. But these bright spots only comprise four percent of the cosmos.
The rest is seemingly a void, nothing but darkness. But the darkness is not empty: It is filled with dark matter and dark energy that has, over the course of the 14 billion years since the big bang, molded the universe into the dynamic structure and shape it holds today. The big bang is the name given to the theory that the universe started with a single cosmic explosion.