The Chicxulub impactor (// CHEEK-shə-loob), also known as the K/Pg impactor and (more speculatively) as the Chicxulub asteroid, was an asteroid or other celestial body some 11 to 81 kilometres (7 to 50 mi) in diameter and having a mass between 1.0×1015 and 4.6×1017 kg, which struck the Earth at the end of the Cretaceous period, approximately 66 million years ago, creating the Chicxulub crater. It impacted a few miles from the present-day town of Chicxulub in Mexico, after which the impactor and its crater are named. Because the estimated date of the object's impact and the Cretaceous–Paleogene boundary (K–Pg boundary) coincide, there is a scientific consensus that its impact was the Cretaceous–Paleogene extinction event which caused the death of the planet's non-avian dinosaurs and many other species.
There are several competing models for the impactor's origin and its relationship to other asteroids that still exist in the Solar System. In September 2007, William F. Bottke, David Vokrouhlický, and David Nesvorný proposed an origin for the impactor in an article published in Nature. They argued that a collision in the asteroid belt 160 million years ago resulted in the Baptistina family of asteroids, the largest surviving member of which is 298 Baptistina. They proposed that the Chicxulub impactor was an asteroid member of this group, referring to the large amount of carbonaceous material present in microscopic fragments at the site, suggesting that it was a member of a rare class of asteroids called carbonaceous chondrites, like Baptistina. According to Bottke, the Chicxulub impactor was a fragment of a much larger parent body about 170 km (110 mi) across, with the impacting body being around 60 km (40 mi) in diameter.
However, in 2011 new data from the Wide-field Infrared Survey Explorer revised the date of the collision which created the Baptistina family to about 80 million years ago, casting doubt on the hypothesis, as typically the process of resonance and collision of an asteroid takes many tens of millions of years.
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- The article by Nicholas M. Short, Sr. appears to have moved, but the image above does not appear to have moved with it. See Crater Morphology Some Characteristic Impact Structures at fas.org, Accessed December 9, 2015.
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