Astronomers hoping to observe a planet around a nearby star have witnessed a much rarer “unprecedented celestial event,” the team said: The violent aftermath of not one, but two collisions between the rocky building blocks of planets.

Over the past two decades, astronomers witnessed two separate catastrophic collisions around the star Fomalhaut, located just 25 light-years away in the constellation Piscis Austrinus. The detections occurred after planetesimals (rocky pieces of unformed planets) measuring much larger than the dinosaur-killing asteroid smashed each other into massive clouds of glittering debris.

The Fomalhaut system is no stranger to such crashes. It’s famously known as the “Eye of Sauron” due to its resemblance to the fiery, all-seeing eye from J.R.R. Tolkien’s Lord of The Rings franchise. The likeness comes from the spectacular dust belt that surrounds Fomalhaut at a distance of 133 astronomical units (AU), with one AU being equal to 93 million miles (150 million km) — the average distance between the sun and Earth.

Formed from countless rocky, icy collisions, this belt of dust and debris provides a dustier analog of our early solar system as it appeared more than 4 billion years ago, the team said — offering a glimpse of our neighborhood’s chaotic infancy, when planets were being created, destroyed, and reassembled.

A new study, conducted by an international team of researchers and led by Paul Kalas, an astronomer at the University of California, Berkeley, described these two collision events in destructive detail to help solve a planetary mystery.

In the early 2000s, astronomers observing the Fomalhaut system spotted a large, luminous object that many assumed to be a dust-covered exoplanet reflecting light. They designated this exoplanet candidate Fomalhaut b.

Yet when this supposed planet blinked out of existence and another bright point of light appeared nearby, all in the span of approximately 20 years, researchers realized they weren’t viewing planets, but the shining debris clouds formed by what they call a “cosmic fender bender.”

The two collision events, now known as Fomalhaut cs1 and Fomalhaut cs2, appear to be incredibly serendipitous. Theory suggests that collisions of this size should only happen once every 100,000 years or so, but the Fomalhaut system surprised scientists with two such smash-ups in just 20 years.