Imperial in the news: dinosaur killers

Asteroid or comet – what caused the impact that killed the dinosaurs?

For generations, the debate has raged as to what exactly caused the extinction of the dinosaurs 65 million years ago. Following a series of varying suggestions, the latest research proposes that the widely-held belief that an asteroid collided with the earth to cause a catastrophic chain of events is wrong. Sort of.

Researchers in the USA announced earlier this month that rather than an asteroid, the impact of the Chicxulub crater in Mexico was caused by a comet. The difference between the two interstellar objects is that comets are made of ice, rock and dust whereas asteroids are made predominantly of metals. Comets’ orbits alter as well, taking more elliptical paths around the sun and moving at faster speeds, while asteroids are often more symmetrical in their trajectories.

Dr Gareth Collins (Earth Science and Engineering) responded to the announcement by saying: “Geochemistry tells you — quite accurately — only the mass of meteoritic material that is distributed globally, not the total mass of the impactor, To estimate the latter, one needs to know what fraction of the impactor was distributed globally, as opposed to being ejected to space or landing close to the crater.” His comments appeared on both the BBC and Huffington Post websites.

Three years ago, Dr Joanna Morgan (Earth Science and Engineering) and Dr Collins produced a report stating that the impact was from an asteroid.

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