Wow! Scientists Confirm the Asteroid Impact that Killed off the Dinosaurs

As someone who is fascinated by dinosaurs, I am excited about recent finding that provided proof of the event that drove them to extinction. Last week, the scientific journal "Science Advances" published an article providing proof that a massive asteroid did crash into the Gulf of Mexico  (off the Yucatan Peninsula) during the Cretaceous period and spread dust in the atmosphere that reduced incoming sunlight and cooled the planet so much it caused the die-off of dinosaurs 66 million years ago. The key was the finding of an element in that impact crater that is rare on Earth but common in some asteroids. In addition to that story and the paper summary in this blog, you'll see a short video by Phil Plaitt who visited an area in Colorado, where he points out the layer of Iridium in a layered area of rock. READ ON>>

HOW DID THE IDEA OF AN ASTEROID COME ABOUT? - In the 1980s, geologists found a "spike" in iridium in geologic layers across Earth. That led to the development of a hypothesis that an asteroid wiped out the dinosaurs because it would likely contain that rare element. A severe impact of such and Iridium-containing asteroid would shoot  the element into the upper atmosphere, where it would circle the globe and drop to Earth. Basically once the atmosphere spread the Iridium like a blanket around the Earth, it eventually fell to the ground, creating an Iridium layer on the soil (which was later covered by more soil over time).  

CRATER SITE FOUND -  In the 1990s, scientists found Chicxulub crater, located off the Yucatan Peninsula of Mexico. 

THE FINDING -  Scientists discovered a thick layer of iridium in the Chicxulub crater. The layer was so thick, scientists were able to precisely date its deposition between days to 2 decades after the asteroid strike!  (So it took as long as 2 decades to fall to Earth).

THE PERIOD OF MASS EXTINCTION- Known as the Cretaceous–Paleogene extinction event as a result of the asteroid, this was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the exception of some ectothermic species such as the sea turtles and crocodilians, no tetrapods weighing more than 25 kilograms survived.

VIDEO: While filming a TV documentary about asteroid impacts, I visited a park in Colorado where the geologic layer marking the mass extinction of the dinosaurs is really easy to see. I decided to make my own short video so I could say a few things that didn't get in to the documentary. I have to say, it was surpassingly cool to stand (well, squat) there and see the K-Pg boundary with my own eyes. TheBadAstronomer LINK: https://youtu.be/2csJfQLFBHw

PAPER SUMMARY (for the more science-minded):  The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak-ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The highest concentration of ultrafine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below the lowermost Danian pelagic limestone. Within years to decades after the impact event, this part of the Chicxulub impact basin returned to a relatively low-energy depositional environment, recording in unprecedented detail the recovery of life during the succeeding millennia. The iridium layer provides a key temporal horizon precisely linking Chicxulub to K-Pg boundary sections worldwide.

PAPER TITLED: "Globally distributed iridium layer preserved within the Chicxulub impact structure View" By Steven Goderis, Honami Sato, Ludovic Ferrière,,Birger Schmitz, David Burney and hundreds more scientists- Link: