On September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC), the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA both measured ripples in the fabric of spacetime – gravitational waves – arriving at the Earth from a cataclysmic event in the distant universe. The new Advanced LIGO detectors had just been brought into operation for their first observing run when the very clear and strong signal was captured. 

Gravitational waves sent out from a pair of colliding black holes have been converted to sound waves, as heard in this animation. On September 14, 2015, LIGO observed gravitational waves from the merger of two black holes, each about 30 times the mass of our sun. The incredibly powerful event, which released 50 times more energy than all the stars in the observable universe, lasted only fractions of a second.