IF A collision with an asteroid is going to finish us off, it will have to be
a lot larger than anyone thought, according to a controversial new study of the
impact that wiped out the dinosaurs.
Virtually everyone agrees that the asteroid that hit Chicxulub in Mexico 65
million years ago killed the dinosaurs, but how it did so is unclear. A
long-standing theory is that clouds of dust hung in the upper atmosphere for
months, blocking sunlight and stopping plants growing. But no one is sure that
this is really the reason, and finding out is critical for…
