Origin Of Dinosaur Killing Object Located

It is pretty stunning that this 66 million year old mystery can be solved at all. 

The key was the chemical composition of the impactor, which contained Ruthenium. This is almost completely absent on Earth apart from rare extraterrestrial impactors, and is also absent in other impactor candidates, including comets and "siliceous asteroids, a class that formed closer to the sun than carbonaceous asteroids and that are concentrated in the asteroid belt between Mars and Jupiter. Most meteorites that end up on Earth’s surface are from this siliceous family."

Unusual Origin Found for Asteroid That Killed the Dinosaurs

A study adds strong evidence to the hypothesis that the deadly rock came from a family of objects that originally formed well beyond the orbit of the planet Jupiter. . . .

The nature of this apocalyptic object, known as the Chicxulub impactor, has inspired intense debates, including a long-running dispute over whether it was a comet or an asteroid. But evidence has been mounting in recent years that the roughly six-mile-wide impactor belonged to a family of asteroids that formed beyond the orbit of Jupiter, and that rarely impact Earth.

Now, a team led by Mario Fischer-Gödde, a research scientist at the University of Cologne in Germany, has bolstered that case with the help of the rare element ruthenium. Ruthenium is abundant in asteroids but extremely scarce in Earth’s crust, making it a handy bellwether of past impacts by space rocks. The team searched for isotopes of ruthenium in the geological remnants of the Chicxulub impact.

The results revealed a uniform signature across the global layer of debris left by the impact, which is known as the Cretaceous-Paleogene (K-Pg) boundary. And that signature neatly matches the makeup of a group of space rocks known as carbonaceous asteroids because of their high-carbon content, according to a study published on Thursday in Science.

From the New York Times.