BOULDER, COLORADO — About 66 million years ago, an object estimated to be 6 miles wide — that’s almost 10 kilometers wide — slammed into the Earth, triggering a cataclysmic series of events that resulted in the demise of non-avian dinosaurs. Now, scientists think they know where that object came from. Here are the details: <br /> <br /> <br />According to new research by the Southwest Research Institute in Colorado, the Chicxulub impact — which scientists say killed off the dinosaurs — was caused by a giant, dark “primitive” asteroid from the outer reaches of the solar system's main asteroid belt, situated between Mars and Jupiter. <br /> <br /> <br />This region is home to many dark asteroids, which are space rocks with a chemical makeup that makes them appear darker than most asteroids. <br /> <br /> <br />Geochemical analysis of the crater also suggests that the impacting object was part of a class of carbonaceous chondrites — a primitive group of meteorites that have a relatively high ratio of carbon and were likely formed very early on in the solar system's history. <br /> <br /> <br />Simulating over hundreds of millions of years, the model showed thermal forces and gravitational tugs from planets periodically slingshotting large asteroids out of the belt. <br /> <br /> <br />On average, an asteroid more than 6 miles wide from the outer edge of the belt was flung into a collision course with Earth once every 250 million years, the researchers found. <br /> <br /> <br />This calculation makes such an event five times more common than previously thought, and consistent with the Chicxulub crater created just 66 million years ago. <br /> <br /> <br /> <br /> <br />
