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Comet, not asteroid, may have killed off dinosaurs, according to study

It seems the demise of the dinosaurs may have been the result of a comet slamming into Earth, not an asteroid.

New research presented this week suggests a fast-moving comet, not an asteroid, caused the extinction of the dinosaurs when it slammed into Mexico’s Yucatan peninsula 65 million years ago. Creating a crater 112 miles wide (180 kilometers), the impact not only killed off non-avian dinosaurs, but also killed 70 percent of all animal species on Earth. Scientists presented their findings at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.

Scientists measured and analyzed the Chicxulub crater, looking at the amounts of iridium and osmium deposited in sediments worldwide. Neither element occurs naturally on Earth in high concentrations, so their presence in higher than expected amounts shows they were deposited on our planet by an object from outer space.

Examining data collected at the site, researchers were able to determine that the massive Chicxulub collision deposited less debris than previously thought. The findings show the space rock  that created the crater was smaller and moving far more faster than previously thought. According to the study’s author, Jason Moore, a paleoecologist at Dartmouth College in New Hampshire, a high velocity comet would have had enough energy to carve out the crater. The massive comet, according to Moore, would have also deposited far less rocky material.

The enormous collision that caused the abrupt, mass extinction of life on Earth is widely seen as one of the most destructive events in Earth’s history. The impact would have set off a massive shock wave traveling at the speed of sound,  firestorms that likely consumed most of Earth, and destructive tsunamis over a mile high. Temperatures on the planet would have been depressed for years as the Earth’s atmosphere remained saturated with gas and dust, blocking out the sun and leading to nuclear winter.

Although scientists believe immense collisions like the one at Chicxulub are extremely rare, when they do occur their effects can be devastating, even apocalyptic. While the dinosaurs are the most well-known victims of the Chicxulub impact, the majority of Earth’s species perished along with them, including mammals, birds, insects, reptiles, and marine life.

The orbits of a majority of comets and asteroids that come close to Earth are less than 50 meters in size, allowing them to burn up when they enter the Earth’s atmosphere. It is estimated that approximately 50,000 space fragments fall on our planet as meteorites each year. Most are too small to do any damage.

On the other hand, a comet or asteroid 300 meters in diameter could obliterate an entire country if it impacted Earth. Even more damage would result if it hit an ocean, as it would trigger gigantic tsunamis capable of devastating coastal areas. According to NASA, only about 10 percent of the 13,000-20,000 asteroids above the size of 140 meters are being tracked. Comets are much more common than asteroids; however, most travel at great distances from the Earth and make up only about 10 percent of the larger objects that have struck the planet.