"'We have wondered why the Milky Way’s black hole appears to be a slumbering giant,' says team leader Tatsuya Inui of Kyoto University in Japan. 'But now we realize that the black hole was far more active in the past. Perhaps it’s just resting after a major outburst.'"
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A black hole 4 million times the mass of our Sun. That thar's a derned big monster. Imagine the flare it must have launched.