Fly Me to the Moon!

Never Underestimate ... The Power of the Asteroid! Ever wonder what life was like 250 million years ago? Maybe it's better if you don't — according to scientists, that's when the Earth experienced a mass extinction, even bigger than the one that wiped out the dinosaurs around 65 million years ago. Luann Becker, of the U. of Washington, holds a rock, which dates back 250 million years ago, when most of the Earth's species were wiped out. Evidence for the mass extinction comes from space gases trapped in little carbon spheres called buckminsterfullerenes, or Buckyballs, a model of which is at right. REUTERS

Scientists are pretty sure that an asteroid measuring four to eight miles across triggered climatic events that killed the dinosaurs. There's even a crater in Mexico to prove it. Now they've found evidence that a similar asteroid hit the Earth well before the dinosaurs and caused the greatest extinction the Earth has ever known.

It Came From Outer Space

Scientists didn't have a crater to help them formulate their theory. Instead, scientists have found tiny molecules called buckyballs in layers of soil that date back 250 million years. The structure of the molecules suggests that they come from space. Scientists concluded that an asteroid must have hit the Earth.

Those layers of soil also suggest that the same era saw lots of volcanic activity. Over a million-year period, there was enough lava to cover the entire planet with 30 feet of rock. In addition, ocean levels dropped by 800 feet. The vaporizing of the oceans, the asteroid impact, and the volcanic activity poisoned the air and the seas. Sunlight may have either become incredibly intense or disappeared completely. Those conditions were enough to wipe out 90 percent of all marine species and 70 percent of land vertebrates within 100,000 years — a blink of an eye considering how long Earth has been around.

A New Beginning

Did the giant asteroid turn the Earth into a wasteland? Not a chance! Scientists believe that the mass extinction triggered a climate change that gave birth to the age of the dinosaurs. Then, millions of years later, a similar asteroid/volcano event killed off the giant lizards and created conditions just right for humans.

Should We Be Colonizing Other Planets?

Are we humans in for a big, disastrous surprise from outer space? Scientists say don't pack your bags for Mars just yet. Asteroids big enough to cause mass extinction only hit the Earth every 100 million years or so. The one that wiped out the dinosaurs hit 65 million years ago, so we're safe for roughly 35 million more years.