Two Supermassive Black Holes Are on a Cosmic Collision Course

Astronomers at the Max Planck Institute discovered two supermassive black holes orbiting each other every 121 days within galaxy Markarian 501, at a distance roughly 250-540 times that between Earth and the sun. After analyzing 23 years of observations, they identified two jets of matter shooting into space, revealing a second black hole previously hidden behind the first. The pair could collide within the next century, creating detectable gravitational waves that scientists could monitor using pulsar timing arrays.