A terrifying asteroid roughly six miles in diameter caused Earth’s last mass extinction, and now scientists have discovered where it happened.
Unlike most space rocks that hit Earth today, this massive object came from beyond the gas giant Jupiter. It was a “C-type asteroid,” a dark, carbon-rich remnant of the outer solar system, and the collision scattered the remains of that fateful object all over Earth about 66 million years ago.
It “was launched from the outer solar system and sealed the fate of the dinosaurs,” Mario Fischer-Gödde, who studies the origins of asteroids and planets at the University of Cologne in Germany, told Mashable.
A NASA scientist saw the first Voyager images, and he was horrified by what he saw.
The new study, led by Fischer-Gedde, was published in a peer-reviewed journal. Science.
The asteroid left a huge mark. Today, the impact zone is called the Chicxulub Crater and is mostly buried beneath the Yucatan Peninsula. The giant object struck shallow waters, shattering tons of rock into the sky and dramatically cooling the climate, which was followed by a long, harsh winter. Photosynthesis stopped, food chains collapsed, and about 70% of Earth’s species died. Some dinosaurs survived.
Mashable Lightspeed
A thin layer of deposits from this event, called the K-Pg boundary, can be found around the Earth. One of the elements in it, ruthenium, is extremely rare in the Earth’s crust, meaning that nearly 100% of the ruthenium in this widespread layer of deposits comes from the infamous asteroid. Importantly, researchers found that the ruthenium isotopes (different types of ruthenium) in this telltale layer are similar to carbon-rich meteorites found throughout the Earth. Additionally, the ruthenium samples did not match any other major asteroid impact debris from objects that formed in the inner solar system.
“We found that the composition of the asteroid that hit Chicxulub is the same as that of carbonaceous meteorites, which are fragments of carbonaceous (C-type) asteroids that originally formed outside the orbit of Jupiter,” Fischer-Gödde said.
Previous studies had suspected a C-type asteroid was the culprit, but they didn’t use ruthenium in their analysis because it’s very difficult to measure, and the latest observations were only possible because of technological advances, Fischer-Gödde explained. Only about three other laboratories in the world, including the University of Cologne, have the ability to carry out this highly specialized study.
C-type asteroid Mathilde, photographed by the NEAR spacecraft on June 27, 1997. It is about 38 miles (61 kilometers) in diameter.
Credit: NASA / JPL / JHUAPL
It depicts an asteroid impact that occurred 66 million years ago, which is thought to have sent a mountain-sized rock hurtling towards Earth.
Credit: NASA / JPL-Caltech
As the solar system formed, many C-type asteroids populated the outskirts of the main asteroid belt, a ring containing millions of rocky objects between Mars and Jupiter. It’s here that the six-mile-wide Chicxulub impactor was propelled toward Earth. This was likely caused by the collision of two asteroids, Fischer-Gedde explained. Alternatively, exposure to sunlight could have heated up some of the space rock, releasing energy that impacted the asteroid (a result known as the “Yarkovsky effect”).
But such gigantic impacts on Earth are extremely rare. “Dinosaur-killing” impacts by rocks half a mile or more in diameter happen every 100 million years. Astronomers have already discovered more than 90% of the “planet-busting” asteroids that pass close to Earth from time to time. There are no known impact threats from these gigantic rocks for the next 100 years, and the likelihood of an impact in the next 1,000 years is extremely low. (By contrast, impacts by objects about 460 feet in diameter occur every 10,000 to 20,000 years, and would be locally catastrophic events.)
Luckily, just in case astronomers find a large asteroid that threatens our humble world, NASA has successfully tested the first-ever attempt to intentionally move an asteroid. Of course, this is a technology that needs to be significantly improved upon, but it could help protect our civilization from future catastrophe.
NASA has never had to even issue a warning about an approaching space rock, big or small, before, but if such an event were to occur, we would likely hear about it not only from excited tabloids, but also from the White House and many other agencies.