Sixty-six million years ago, the sky fell.
A 10km asteroid struck the Yucatan.
Energy one million times greater than any human weapon.
Oceans rose in gigantic tsunamis.
Forests burned in global fires.
Dust covered the sky.
A winter that lasted for years.
Three-quarters of all species vanished.
The dinosaurs were gone.
This was the most famous extinction.
But it was not the worst.