Black Holes Overpowered All Starlight

On September 14, 2015, LIGO made the first direct observation of gravitational waves when two black holes about 36 and 29 times the Sun's mass spiralled together and merged 1.4 billion light-years away. The collision created a 62-solar-mass black hole, converting roughly three Suns' worth of mass into gravitational-wave energy. During the final 20 milliseconds, its power output peaked at 3.6 x 10^49 watts, about 50 times the combined power of all light radiated by every star in the observable universe. The 0.2-second signal, named GW150914, confirmed a major prediction of general relativity and launched gravitational-wave astronomy.

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