Astronomers Detect Planetary Collision Near Sun-like Star

Astronomers have detected compelling evidence of a violent collision between two planets orbiting a Sun-like star 11,000 light-years away, capturing in real time an event that mirrors the ancient impact believed to have formed Earth's Moon. The discovery, centered on the main-sequence star Gaia20ehk in the constellation Puppis, was detailed in a study published Wednesday in The Astrophysical Journal Letters.

The observation began with unusual fluctuations in the star's brightness. For years, Gaia20ehk exhibited the steady light output typical of stars like the Sun. That changed in 2016, when its brightness dipped three times over brief periods. By 2021, the variations became erratic and intense. "The star's light output was nice and flat, but starting in 2016 it had these three dips in brightness. And then, right around 2021, it went completely bonkers," said lead author Anastasios Tzanidakis, a doctoral candidate at the University of Washington. "I can't emphasize enough that stars like our Sun don't do that. So when we saw this one, we were like, 'Hello, what's going on here?'"

Analysis revealed that the flickering stemmed not from the star itself but from vast clouds of rock...