In 1928, the astronomer Edwin Hubble forever changed our vision of the cosmos.  Observing from the 200-inch telescope on Mount Palomar, Hubble realized that galaxies around us were flying away from each other -- the result of a massive explosion that marked the birth of our universe.  

Measuring their speed, the exact time of of “big bang” could be pinpointed --  13.8 billion years ago.

Expanding from a single tiny point, fragments of matter and energy condensed into hydrogen atoms that swirled together to form suns and galaxies.  New elements were forged in the hearts of stars and from stellar explosions. It was 4.6 billion years ago when a thin molecular cloud, now enriched with metals, began forming the nebula that would one day become our own solar system.

  Edwin Hubble

Timeline of the Universe