Astronomers observed flashes of X-rays coming from a supermassive black hole at a steadily increasing clip. The source could be the core of a dead star that's teetering at the black hole's edge.

Scientists have come a step closer to understanding how collisionless shock waves -- found throughout the universe -- are able to accelerate particles to extreme speeds.

Radiation-induced mutation is unlikely to have induced genetic differences between dog populations in Chornobyl City and the nearby Chornobyl Nuclear Power Plant.