About 14 billion years ago a tremendous explosion started the expansion of the universe. This explosion is known as the Big Bang. At the point of this event all of the matter and energy of space was contained at one point. What
existed prior to this event is completely unknown and is a matter of pure speculation. This
occurrence was not a conventional explosion but rather an event filling all of space with all of the particles of the embryonic universe rushing away from each other.
It has since expanded from this hot dense state into the vast and much
cooler cosmos we currently inhabit. We can see remnants of this hot dense
matter as the now very cold cosmic microwave background radiation which
still pervades the universe and is visible to microwave detectors as a
uniform glow across the entire sky. The Big Bang Model is a broadly
accepted theory for the origin and evolution of our universe.
The evolution of the Universe started about 14 billion years ago when all of the matter and energy in the Universe was concentrated into an area the size of an atom. At this moment, matter, energy, space and time did not exist. Then suddenly, the Universe began to expand at an incredible rate and matter, energy, space and time came into being. As the Universe expanded, matter began to coalesce into gas clouds, and then stars and planets. Our solar system formed about 5 billion years ago when the Universe was about 65% of its present size. Today, the Universe continues to expand.