Scientists now believe they know where the asteroid that wiped out the dinosaurs came from

The extinction of the dinosaurs is a hotly debated topic. While volcanic eruptions and plant species poisoning dinosaurs have been debated, researchers at the crater in Chicxulub, Mexico, have found solid evidence of an asteroid impact that had a massive impact on Earth's climate, as well as asteroid-specific minerals such as iridium, practically proving the asteroid theory.

And now scientists have figured out where the asteroid probably came from, and it didn't come from anywhere nearby. Research led by Mario Fischer-Gödde at the University of Cologne has found that the asteroid came from beyond Jupiter, well outside our solar system.

The research, published Thursday in the journal Science, identifies the asteroid as a C-type asteroid. These meteors, known as carbonaceous meteors, mostly come from the outer solar system. C-type meteors are exceptionally old, and their composition can help researchers learn more about the early history of our solar system.

Find out where the meteorite came from

To find out, scientists had to go through a series of steps. When the meteorite hit the Earth, it pulverized rock and hurled it into the sky. This huge cloud of dust – which contained material from both the Earth and the meteorite – lowered the Earth's temperature and wiped out most existing species. This dust eventually settled and formed a layer of rock that scientists were able to excavate tens of millions of years later.

Geologists call this very thin layer the K-Pg layer, which describes the time when the Cretaceous period ends and the Paleogene period begins. The asteroid is believed to have struck around this time, 66 million years ago.

Researchers dug up samples from the K-Pg layer and found ruthenium, an element that is rare on Earth but is present in large quantities in carbonaceous meteorites. The isotopes, or atoms, found in the ruthenium matched those found in ruthenium in other carbonaceous meteorites, proving that it came from a meteorite and not from Earth.

To be sure, the researchers also compared it with material found from other large meteorite impacts and found no matches. This means that the ruthenium found in the K-Pg layer came from the same meteorite that hit Chicxulub.

How does this fit with the theory that an asteroid wiped out the dinosaurs?

According to the theory, a 6-mile-wide meteor crashed into Earth near what is now Chicxulub on the Yucatan Peninsula. The impact sent vaporized rocks and debris flying, covering the planet in a cloud of dust that dropped the temperature by about 28 degrees Celsius. This led to a long winter that wiped out non-avian dinosaurs and 70 percent of all life on Earth.

Eventually the dust fell back to Earth, where it became the K-Pg layer of rock, and then other things were piled on top of it, which also became rock. Whatever happened to create the K-Pg layer definitely wiped out the dinosaurs, because no non-avian dinosaur fossils have ever been found above the K-Pg layer.

Researchers have found a lot of material in the K-Pg layer, including iridium and chromium. Iridium is rare on Earth but common on asteroids, so when they found iridium in the 1980s, it helped solve the mystery of what wiped out the dinosaurs. Chromium, on the other hand, is very common on Earth and so could not be linked to a meteorite impact.

Later, scientists found further evidence in the form of sulfur in the K-Pg layer, but not in the impact crater. This suggests that the impact spewed sulfur into the atmosphere, which certainly contributed to global cooling. Sulfur has even been found in rocks in Antarctica, showing how violent the meteorite impact was.

Now let's move on to the present. As Fischer-Gödde explained to Mashable, ruthenium is quite difficult to detect and it took some technological advances to achieve this. So the team measured five samples from the K-Pg layer and found that the ruthenium in all five samples likely came from the same single source. They also found that the isotopes matched those of previously analyzed carbonaceous meteorites.

To summarize, the meteorite that hit Earth and killed the dinosaurs probably formed billions of years ago during the earliest history of the solar system, rather than in a local location like most meteorite impacts.