For hundreds of millions of years, two city-sized stars — each outweighing
our sun — circled one another in a fatal dance. They were neutron stars,
the collapsed cores left behind after giant stars explode into supernovas.
Then, 130 million years ago, the dance ended. Their collision was fast and
violent, likely spawning a black hole. And a shudder — a gravitational wave
— rippled across the fabric of space-time. Light from the cataclysm
followed seconds later.
The space-time distortion and the light reached Earth together on Aug. 17,
making astronomical history. Astronomers announced the finding Oct. 16.
The gravitational wave first reached Italy’s just-finished detector,
Advanced Virgo, before stretching and squeezing the two LIGO observatories
in the United States. Orbiting space telescopes and instruments on all
seven continents turned to watch the cosmic collision play out in all
manner of light: radio, infrared, optical, ultraviolet, X-rays, gamma rays.
“It was extremely close to us, and so it was an extremely strong signal,”
says LIGO scientist Jolien Creighton of the University of