Infrared light reveals size of asteroids

Telescopes, which capture visible light, have difficulties distinguishing between a small, light asteroid and a large, dark one, because light surfaces reflect more visible light than darks ones. This is known as albedo. The NEOCam telescope captures infrared light, which we normally associate with heat. Large objects emit more heat radiation than small ones, and so, the method is more accurate for determining size. With an infrared telescope, it is, moreover, possible to spot an entirely dark asteroid.