Photo by Randy Montoya, courtesy Sandia National Laboratories

In 1908, there was an enormous explosion over the Tunguska River in Russia, which flattened trees over 800 square miles with the force of an atomic bomb. It has long been speculated that this was an airburst of a meteor, but scientists did not have the tools to decisively model the event. Now the Sandia National Lab has accomplished this with new supercomputer simulation techniques, and the results are frightening.

“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”
— Via Sandia National Labs

Why do we care? This analysis suggests that much smaller rocks, hitting the atmosphere at very high relative velocities, can produce enormous effects when they explode in mid-air, sending powerful fireballs downward toward the surface. (Check out the simulation movies to see). We may have a lot more to worry about than the 10-mile-wide dinosaur killing asteroids. On the Slashdot thread, the diameter of the object is calculated at 58 meters (190 feet). Very, very hard to spot something that small coming at us from space.

Hat tip to malachorion on Slashdot.