The captivating flickering of the young F-type star, Gaia-20ehk, along with the expanding dust cloud encircling it, indicates a dramatic planetary collision unfolding in real time. This event provides a unique opportunity to observe the violent processes involved in the formation of nascent planetary systems.

Located approximately 11,000 light-years from Earth in the constellation Leo, Gaia20ehk is a stable “main sequence” star, typically known for its steady and predictable luminosity. However, since 2016, this star has exhibited violent flickering.

“Initially, the star’s light output was consistent, but it has since dropped by around 3 degrees,” remarked Anastasios (Andy) Tzanidakis, a doctoral candidate at the University of Washington. “By 2021, the situation escalated dramatically.”

“Such behavior is unexpected for stars like our Sun. When we observed this, we thought, ‘What could be happening here?'”

The flickering of Gaia20ehk is not due to the star itself. Instead, it is caused by a cloud of rocks and dust obstructing the light as it orbits the system.

The astounding source of this debris appears to be a catastrophic planetary collision.

“It’s remarkable that multiple telescopes captured this impact in real time,” Tzanidakis stated.

“There are only a handful of documented planetary collisions, and none possess as many parallels to the impacts that formed Earth and the Moon.”

“Observing similar events in other parts of the galaxy could significantly enhance our understanding of our planet’s formation.”

Additionally, evidence suggests this impact may closely resemble the one that created the Earth and Moon approximately 4.5 billion years ago.

This dust cloud orbits Gaia20ehk at about 1 astronomical unit, the same distance from its star as Earth is from the Sun.

At this distance, materials could eventually cool and solidify into structures akin to the Earth-Moon system.

“How rare was the event that shaped the Earth and Moon? This inquiry is essential to the field of astrobiology,” commented James Davenport, a professor at the University of Washington.

“The Moon seems to play a crucial role in making Earth a habitable place, shielding it from some asteroids, influencing ocean tides and weather patterns, and potentially even facilitating geological activity.”

“Currently, the prevalence of these dynamics remains uncertain, but as we observe more collisions, we will gain clearer insights.”

The team’s research paper will be published in today’s Astrophysical Journal Letters.

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Anastasios Zanidakis & James R.A. Davenport. 2026. Gaia-GIC-1: Evolving catastrophic planetesimal impact candidate. APJL 1000, L5; doi: 10.3847/2041-8213/ae3ddc