Stacy McGaugh
CWRU Faculty Department of Astronomy

Cosmic History
The history of the universe spans fourteen billion years, unfolding here from top to bottom. It begins with the fiery crucible of the Big Bang in which light, matter, and the first elements are created. The universe cools as it expands, transitioning suddenly from an opaque, fog-like plasma to a transparent gas. This dark age ends after a few hundred million years, cosmic dawn being ushered in by the formation of the first stars. These light the unfathomable expanse of deep space and explode as supernovae that synthesize heavy elements to provide the seeds for cosmic dust, future stars, planets, and ultimately life. Stars and gas collect together under the influence of gravity to form small galaxies that merge to form ever larger galaxies until giant galaxies emerge like our very own Milky Way. Light from the most remote corner of creation must travel for billions of years from the dawn of time to reach the eager eyes of human observers at their telescopes below, provided it is not absorbed by clouds in the atmosphere in the last millisecond of a journey spanning eons.