World's worst day

When thinking about the dinosaurs, I tend to image a rain of asteroids falling down to the Earth, which bring down the dinosaurs. Last week, I learned from a science seminar that after three decades of research, the consensus of the scientific community is now believe that it just took 1 single, asteroid to cause that destruction which ended the 161-million year reign of the dinosaurs. According to computer models, it goes something like this ....
without warning some 65 million years ago, an unnamed and unwelcome visitor from deep in space. By the time it plowed into the Earth (at Yucatan Peninsula), this six-mile-wide mass of rock and mineral was traveling as fast as 20 kilometers per second, more than 50 times the speed of sound. The asteroid's energy at touchdown would have equaled the force of 300 million nuclear weapons. This wasn't the first time the Earth had absorbed a major asteroid impact. But our planet had never experienced anything quite like this. This was the world's worst day.