Hunting the Edge of Space premieres April 6 & 13 on PBS at 8PM ET/PT (please check local listings). Hour 2 begins at the dawn of the 20th century, when astronomers still believed that the entire universe lay within the Milky Way. That was before George Ellery Hale, who built the greatest telescopes of the 20th century, and Edwin Hubble, who used Hales 100 telescope on Mt. Wilson, California, to prove that the universe is populated by untold numbers of galaxies, all of which lie far beyond the confines of our Milky Way.