For thousands of years, the most consistent, spectacular meteor shower has been the Perseids, created by Comet 109P/Swift-Tuttle. At its incredibly large size (26 kilometers across) and speed, it contains nearly 30 times the energy of the asteroid strike that wiped out the dinosaurs... If Jupiter — which it also passes by — gives it just the slightest gravitational kick, it could be flung into the Sun, ejected from the Solar System, or hurtled directly into our world. If this were to happen, and it's a real possibility some 2400 years from now, it would mark the largest mass extinction...