Astronomers collect rare evidence of two planets colliding
by William Poor, University of Washington. 11 March 2026
Anastasios (Andy) Tzanidakis was combing through old telescope data from 2020 when he found an otherwise boring star acting very strangely. The star, named Gaia20ehk, was about 11,000 light-years from Earth near the constellation Puppis. It was a stable "main sequence" star, much like our sun, which meant that it should emit steady, predictable light. Yet this star began to flicker wildly.
"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 Tzanidakis, a doctoral candidate in astronomy 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?'"
The cause of the flickering had nothing to do with the star itself: Huge quantities of rocks and dust—seemingly from out of nowhere—were passing in front of the distant star as the material orbited the system, patchily dimming the light that reached Earth. The likely source of all that debris was even more remarkable: a catastrophic collision between two planets.
"It's incredible that various telescopes caught this impact in real time," Tzanidakis said. "There are only a few other planetary collisions of any kind on record, and none that bear so many similarities to the impact that created Earth and the moon. If we can observe more moments like this elsewhere in the galaxy, it will teach us lots about the formation of our world."
The analysis of the star is published in The Astrophysical Journal Letters.
Article link:
https://phys.org/news/2026-03-astronomers-rare-evidence-planets-colliding.html
Pic Descriptions:
PIC 1 (Top): Lead author Andy Tzanidakis’s rendering of the planetary collision he suspects occurred around star Gaia20ehk in 2021. Credit: Andy Tzanidakis
PIC 2: Star Gaia20ehk—seen here in the center of the orange crosshairs in the inset image—is roughly 11,000 light-years from Earth, near the constellation Puppis. Photo: NASA/NSF NOIRLab