Scientists have discovered that a high-energy flare ripped through the galaxy in the relatively recent past. The cataclysmic event was thought to have been triggered by nuclear activity associated with Sagittarius A* - a gargantuan black hole four million times the mass of the Sun. It occurred 3.5 million years ago and could be felt over a distance of 200,000 light years. Scientists believe that the flare produced two enormous 'isolation cones' which sliced through the galaxy, leaving behind a trail of gas that extends between the Large and Small Magellanic Clouds. "The flare must have been a bit like a lighthouse beam," said study team leader Prof Bland-Hawthorn from the University of Sydney. "Imagine darkness, and then someone switches on a lighthouse beacon for a brief period of time." The discovery suggests that our galaxy is a lot more active that previously thought. "These results dramatically change our understanding of the Milky Way," said study co-author Magda Guglielmo. "We