Two animations, separated by just over half a century. In Walt Disney’s Fantasia, Stravinsky’s Rite of Spring is set to a history of the Earth, featuring the dinosaurs gradually dying out in a drought. In 1994, an animated segment from Blue Peter shows the story we’re all with familiar today: a huge asteroid hitting the Earth, causing widespread destruction and an ‘impact winter’ that kills off the dinosaurs’ source of food.

How did we get from the one to the other? This was the question Steve Miller (UCL’s Professor of Science Communication and Planetary Science) sought answers to in his Lunch Hour Lecture, ‘The impact of impacts’ (3 February).

The story begins with a paper in 1980 that pointed out that there was a buried layer of iridium that covered the entire world and was the same age as the last of the dinosaurs. Iridium is an extremely rare element on Earth, but much more common in meteorites.

The research argued that the impact of an asteroid about 10km across could explain both the unexpected iridium and the sudden disappearance of the dinosaurs.

Gravitational map of the Chixculub crater on the Yucatan Peninsula. Credit: Geological Survey of Canada

(more…)