The asteroid that caused our last mass extinction 66 million years ago — wiping out the dinosaurs in the process — came from the farthest reaches of our solar system, unlike most asteroids that have hit Earth, a new study shows.

Researchers in Europe and the United States have discovered that the dinosaur-killing asteroid formed beyond the orbit of Jupiter in an extremely cold region and was rich in water and carbon, according to findings published Thursday in the journal Science.

The researchers said that of all the cosmic bodies they have studied that have hit Earth in the past 500 million years, only the one that wiped out the dinosaurs was a water-rich asteroid. Objects that form closer to the sun are much drier, said François Tissot, a professor at the California Institute of Technology who co-authored the study.

“Every other impact was an object that was close to the sun and happened to hit here,” Tissot said. “So the impact that killed the dinosaurs is very special in two ways: by what it did and also by where it came from.”

This apocalyptic object created the Chicxulub crater on Mexico’s Yucatán Peninsula. Although researchers were unable to study a direct sample of the asteroid because it was destroyed, Tissot explained that dust from the impact fell back to Earth, allowing them to study the fine particles deposited in the Earth’s layers.

Specifically, they examined the element ruthenium, which is extremely rare on Earth and could definitely be traced back to this asteroid.

The study confirmed previous findings that identified the asteroid as a carbonaceous C-type asteroid, but refuted a 2021 hypothesis that the dinosaur killer was likely a comet.

“Comets come from very far from the sun, but they are mostly made of ice and dust,” Tissot said. “No comet has been measured to contain ruthenium, so we have no point of comparison, but based on other indicators of other elements that the community has been able to measure over time, it seems very unlikely that this is a comet.”

Tissot noted that the study represents progress in efforts to understand the evolution of our planet.

“If enough studies are done throughout Earth’s history, then suddenly we have a record of the entire evolution of the Earth,” he said, “and we can start asking other questions.”

This article was originally published on NBCNews.com.