Less than four months after getting switched back on — and only days after its “next light” images — NASA’s re-commissioned NEOWISE mission has made its first discovery: a never-before-seen near-Earth asteroid 27 million miles (43 million km) away. Identified in a series of images captured on Dec. 29, 2013 YP139 is a coal-black asteroid about 650 meters — over 2,100 feet — wide. The image above shows the asteroid as a circled red dot as it moved across NEOWISE’s field of view over a period of several hours. 2013 YP139 would be all but invisible in optical light because...