The collision of two neutron stars, triggering a flash brighter than a billion suns and causing ripples through space-time, has been witnessed by astronomers for the first time. After the two incredibly dense stars smashed into each other, they almost certainly immediately collapsed into a black hole. The event was detected by the Laser Interferometer Gravitational-Wave Observatory (Ligo), based in Louisiana and Washington state, USA. Astronomers were then able to observe the red-tinged afterglow in the night sky through telescopes. The collision took place around 130 million light years from Earth, which is the distance travelled by light emitted 130 million years ago—that is, during the Age of Dinosaurs.

Albert Einstein first predicted the existence of gravitational waves a century ago, but the first proof that space itself can be stretched and squeezed came in 2015, when Ligo scientists detected a collision between two black holes. This event, however, was invisible to conventional telescopes. This time, as the neutron stars collided they gave off an intense beam of gamma rays, which telescopes both on the ground and in space could detect. Dave Reitze, executive director of Ligo, said: “What is amazing about this discovery is it is the first time we’ve got a full picture of one of the most violent, cataclysmic events in the universe.”

On impact, an intense burst of gamma rays was emitted as jets of matter were blown out of the poles. There would have been an almost instantaneous collapse into a black hole. Scientists believe it was probably the first time the creation of a black hole had ever been witnessed. Ligo even picked up the sound of the collision: a 100-second hum that rose in pitch to a whistle as the stars careered towards one another.