3:02 PM

EducationGuardian.co.uk | Higher | Antarctic craters reveal asteroid strike:

But it was not until this year, when two satellites operating above Antarctica began to map the anomalies in the gravity, that the scale of the crater emerged. The mapping showed that the holes in the rock created by the strike had refilled with a mixture of ice, rock and other debris far less dense. This material, called breccia, shows where and how deep the craters are.

Prof Van der Hoeven said: “The extraordinary thing about this meteor strike is that it appeared to do so little damage. Unlike the dinosaur strike there is no telltale layer of dust that demonstrates the history of the event. It may have damaged things and wiped out species but there is no sign of it.”

One thing that did happen at exactly the same time was the reversing of the Earth’s magnetic field. There is no other explanation as to why this took place and Prof Van der Hoeven believes it was caused by the impact.