Anatoly Perminov, head of the Russian Space Agency, caught scientists off guard when he called for a closed meeting of Russian scientists to counter a killer asteroid headed our way. He said that a potential impact from the asteroid Apothis around 2036 could kill hundreds of thousands of people. Immediately this conjured up images of Bruce Willis and his space cowboys riding the Space Shuttle to blow up a comet in the movie "Armageddon." Scientists, realizing that the danger is slight but real, have in fact seriously proposed various ways in which to deflect the asteroid.

The Russians take such a threat seriously, since a "city buster" hit Tunguska, Siberia, in 1908, flattening about a thousand square miles of forest, destroying about 100 million trees, and leaving a huge scar in the Earth. The object that struck Siberia was probably only 100 feet across, yet it created a blast about 1,000 times greater than the Hiroshima bomb. The shock waves were so intense they were detected in Europe. It created a strange glow which spread over Asia and Europe so that you could read the London papers at night. If it had hit Moscow, it would have completely flattened that city and beyond. A city-buster like that happens once every 100-300 years, with most of them hitting the oceans.

Plans to counter such a hypothetical threat, however, are sketchy. A staple of science fiction is to send the Space Shuttle to blow it up. Bad idea.