How large was the asteroid that hit Earth and killed all the dinosaurs? NASA says it was THIS big

tech.hindustantimes.com:

While we all know that dinosaurs died because of a massive asteroid strike against the Earth, many of us still do not understand how an asteroid that impacted one local geographic location can kill all life forms across the planet. And most importantly, how large does an asteroid have to be in order to destroy an entire species and cause an ice age. A new BBC documentary called Dinosaurs: The Final Day is going to tell us the tale of the last 24 hours of these creatures on Earth. To make it even better, famous historian and broadcaster David Attenborough will be narrating the entire event. The documentary will also answer one of most asked questions relating to the dinosaur extinction – how large was the asteroid that hit the Earth?

Thanks to NASA, we do know the answer to that question. For a visual reference, it was as big as Mount Everest. Yes, we are not kidding. The asteroid that ended all dinosaur lives and became Earth-killer was between 9-12 kilometers wide. Around 66 million years ago, it struck the Earth in the Gulf of Mexico's Yucatan Peninsula creating the 180-kilometer wide Chicxulub crater in an event which would later be known as the Cretaceous-Paleogene (K-Pg) extinction event.

Simulations have shown that within hours of the asteroid strike on Earth, earthquakes, tsunamis and global firestorms would have started, killing dinosaurs. But it would also have had long term impacts with the dust and sulfate aerosol covering the atmosphere would have cooled down the Earth and triggered an ice age.

The knowledge that an asteroid between the size of 10-15 kms can have such an extreme impact on the planet has helped NASA and the entire astronomy community to create a threat assessment system to monitor any asteroid in