The Millennium that Defines Universe . ... Credit Copyright: R. J. Nemiroff ( Michigan Tech ) Explanation: Welcome to the millennial year at the threshold of millennium three . During millennium two , humanity continually redefined its concept of "Universe": first as spheres centered on the Earth , in mid-millennium as the Solar System , a few centuries ago as the Galaxy , and within the last century as the matter emanating from the Big Bang . ... NASA Official: Jay Norris. ... Michigan Tech. ...