Rogue black holes are usually detected by the matter falling into them, but the first truly isolated black hole has been found because of the way it bends the light of a distant star
An isolated stellar-mass black hole has been detected floating through interstellar space for the first time.
Astronomers typically spot black holes by measuring their interactions with nearby stars, which can produce vast plumes of gas or radiation. But isolated stars, which astronomers have observed in their millions, imply that isolated black holes should also fill the sky, as dying stars can birth black holes once they explode in a supernova.
“[Isolated stellar-mass black holes] aren’t rare, but they’ve never been found,” says …