On a summer night in Phoenix, city dwellers can watch a line of head lamps inch up Piestewa Peak. The mountain rises sharply more than 1,200 feet above the neighborhoods of Central Phoenix. It's the most popular outdoor trek in the city. But in July and August the sun turns deadly there and hikers wait until it's safely below the horizon to begin their ascent. At the top, the view unfolds like magic every time — a desert city of four million people that glows red, white and orange.