Hundreds of earthlings turned their faces to the sky Monday to see an airplane built to launch a ship into space, watching the gleaming white craft soar overhead. The twin-fuselage craft named “WhiteKnightTwo,” looking like two planes connected at the wing tips, circled the runway several times before touching down at the Experimental Aircraft Association’s Air Venture annual gathering. It was the first glimpse the public had of the plane, which was made by Virgin Galactic as part of its effort to jump-start commercial space travel.