Eighty percent of the world's population can't see the Milky Way. Light pollution interferes. Author and adventurer Craig Childs, of Norwood, Colorado, writes about a trek from light to dark in his new book. "The Wild Dark" takes readers from the incandescence of Las Vegas to the spangled skies of rural Nevada. Childs spoke with Sr. Host Ryan Warner at the Mountain Words Festival in Crested Butte in May.