Nearly one million near-earth asteroids that are large enough to destroy a major city are circling through space, undetected. What's the chance that one will hit the earth?
According to former NASA astronaut Ed Lu, it's inevitable. "It's not just a theoretical construct -- it's 100 percent true that you cannot play the odds forever and win. We take a risk every day when we fly around the solar system, and eventually, our number will be up," he said during an interview at the Aspen Ideas Festival on Friday.
The last time an asteroid hit the earth and did significant damage was 105 years ago in Tunguska, Siberia, which took out an area roughly the size of the Los Angeles basin (appx. 35 miles long and 15 miles wide). "Those happen about every 200 years, so in this century, there's about a 30 percent chance we'll see another one," Lu warned.
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