Asteroid Impact

[Tartar Horde]

The data for Asteroid/Comet impacts come from a range of studies and ground work carried out by Geologists, Palaeontologists and mathematicians.
The most well known academic work on the subject was carried out by
Nobel physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Michels, who investigated the Cretaceous Tertiary boundary which signifies the extinction of the Dinosaurs, and linked their evidence to show an Asteroid impact just off the Yucatan peninsula at a place called Chicxulub.
The global affects of the impact have been studied all around the World, as have the amounts of energy etc released.
research KT extinction event.
For a bit of fun here's where you get to play God and smite the unrighteous
http://www.purdue.edu/impactearth

http://impact.ese.ic.ac.uk/ImpactEffects/