ASTEROID EXPLODES OVER SUDAN, and there was some warning that it was on the way: “While boulders of various sizes routinely hit the Earth’s atmosphere, this was the first time that astronomers saw one coming and accurately predicted the time and place of impact, UH astronomer David Tholen said yesterday.” Plus, an Army of Davids effect: “JPL and the University of Pisa have software for impact calculations, but some amateurs did their own calculations, which were ‘remarkably consistent’ with professional groups, Tholen said.”