Although astronomers cannot directly witness the universe's formation, much of what we know about the Big Bang Theory comes from advanced mathematical models ... The three most important ...

From the hundreds of galaxies we can see in this very small patch of sky, we can estimate that there are about 50 billion galaxies in the universe. The 3-D model below will show you the structure ...

after it had been predicted by the theory, provided very strong support for the Big Bang theory, and led to the Big Bang becoming the currently accepted model of the development of the Universe.

The universe began with a vast explosion that generated ... more familiar forms of matter and energy. From one billion to three billion years after the big bang many smaller galaxies merged ...