Before there was a Milky Way galaxy, a solar system or planet Earth, the Universe — as if taking a nap after the birth effort of the Big Bang — was wrapped in a blanket of cosmic fog. There were as yet no stars nor galaxies. Cosmologically speaking, it was the Dark Ages.  Renyue Center, Princeton University (top) and Hy Trac, Carnegie Mellon University  Initially, in that first mysterious microsecond about 13.7 billion years ago, there was light. And then an instant after the Big Bang, as the prevailing cosmological theory is often called, matter was an expanding soup of elementary particles, quarks and gluons and photons, which in turn evolved into a plasma, an ultra-hot swirl of protons, neutrons and electrons — with temperatures too hot for atoms to form. As the plasma cooled and the rapidly growing baby Universe was still very young — around 380,000 years, protons and electrons came together and made neutral hydrogen atoms. To read further, please visit http://psc.edu/science/2012/cosmos/.