It took only a split-second for a black hole in outer space to swallow a neutron star, the densest object known in the universe. And for the first time ever, astronomers watched it happen—sort of. What they couldn’t see with their eyes, they could detect by tracking changes in gravitational waves. Ten days after the first crash, they saw the same thing happen again, this time on the other side of the universe.
Astronomers witnessed the last 500 orbits each star took before slamming into the black holes. The whole process took far less than a minute. In both cases, a neutron star orbits closer and closer to the ultimate point of no return, known as a black hole. The incredibly heavy star, a teaspoon of which would weigh a billion tons, eventually crashes straight into the black hole. In the blink of an eye, the neutron star gets gobbled up.
“It was just a big quick (gulp), gone,” says Patrick Brady, an astrophysicist at the University of Wisconsin Milwaukee. According to Brady, the black hole “gets a nice dinner of a neutron star and makes itself just a little bit more massive.”
A neutron star is the remains of a massive star. It is the leftover matter when a big star dies in a supernova explosion. Neutron stars are so dense that they contain one and a half to two times the mass of our Sun! They are heavy, but not large. A neutron star is only about six miles wide.
A black hole is an area of space where gravity is so strong that nothing can escape it. When a big star collapses into itself, it can become a black hole. The collapse creates something with such powerful gravity that not even light can escape.
How did astronomers know exactly when to watch for the cosmic crash? They detected bursts of energy from the collisions in January of 2020. Detectors on Earth spotted gravitational waves caused by the collision of the neutron stars and black holes. This wasn’t the first time that astronomers have noticed the gravitational ripples from a black hole or a neutron star. But it is the first time they could identify one of each crashing together.
“This is very cool,” says Johns Hopkins University astrophysicist Marc Kamionkowski. He says this latest research will help astronomers predict how abundant these neutron star and black hole pairings are. Of course, God knows the exact number of all the universe’s structures, as Psalm 147:4 reminds us. “He determines the number of the stars; He gives to all of them their names.”