Planetesimal wrecks are raging around distant stars. With the Webb and Spitzer Space Telescopes, astronomers are learning what that looks like.

An artist's conception shows a Mars-size object named Theia hitting Earth just after the birth of the solar system.

NASA / JPL-Caltech

It reads almost like mythology: Long, long ago, only 100 million or so years after the Sun began to burn, a Mars-size object named Theia rammed into the infant Earth. Out of that cataclysm, the Moon was born.

But it’s not mythology. Collisions are a key part of planet formation around every young star. It’s just that giant collisions, like the one Earth experienced, appear to be rare, occurring only in 1% of the planet-forming stars astronomers have observed. Now, astronomers are getting a better look at these rare systems with data from the Spitzer and James Webb space telescopes.…