Astronomers Detect Rare Planetary Collision Near Sun-Like Star 11,000 Light-Years Away

While analyzing archival telescopic data from 2020, Anastasios (Andy) Tzanidakis, a doctoral candidate in astronomy at the University of Washington (UW), uncovered evidence of a rare and violent cosmic cataclysm. The subject of the study is Gaia20ehk, a star located approximately 11,000 light-years from Earth in the direction of the Puppis constellation. This discovery offers a unique window into the high-energy events that shape distant planetary systems and provides a rare glimpse into the chaotic dynamics that can occur in solar systems similar to our own.

Gaia20ehk is a stable main-sequence star with physical characteristics very similar to our Sun, which typically suggests a steady and predictable level of brightness. However, starting in 2016, astronomers recorded three distinct instances where the star's light dipped significantly. By 2021, the light flow had become completely chaotic, a behavior that is highly atypical for sun-like stars. Researchers determined that the cause of this anomaly was the presence of colossal volumes of rock and dust orbiting the star and periodically blocking the light reaching Earth.

The most likely source of this extensive debris cloud was identified as a catastrophic event: a direct collision between two planets that were orbiting Gaia20ehk. James Davenport, an associate professor of astronomy at UW and the senior author of the study, pointed to a critical diagnostic sign. He noted that as the visible light dropped, there was a simultaneous and sharp spike in the infrared spectrum. This thermal profile is a definitive match for a powerful planetary impact that generates massive amounts of energy, distinguishing it from less energetic glancing collisions. The study, published on March 11, 2026, in The Astrophysical Journal Letters, confirms that the event shares striking similarities with the hypothetical impact believed to have formed the Earth-Moon system roughly four and a half billion years ago.

The resulting cloud of wreckage in the Gaia20ehk system is currently orbiting at a distance of one astronomical unit (AU) from the star, which is exactly the distance between the Earth and the Sun. This provides researchers with an unprecedented opportunity to observe the fundamental processes of planetary formation in real-time. Such insights are of vital importance to the field of astrobiology, given the Moon's essential role in stabilizing the conditions necessary for life on Earth. Furthermore, the success of infrared analysis in this case provides a robust method for astronomers to differentiate major planetary crashes from other types of stellar obscuration events.

Davenport anticipates that the search for these cosmic collisions is only just beginning. Thanks to the commissioning of the Vera C. Rubin Observatory, which became operational in 2025, scientists expect to identify as many as 100 new collision candidates over the coming decade. This will greatly expand our knowledge of how frequently Earth-like formation scenarios occur in the universe. At present, the debris in the Gaia20ehk system is beginning to cool, and it will likely take centuries for astronomers to see if the material eventually coalesces into a new planet, a set of rings, or a system with a large satellite.