In 1908, the skies over Siberia lit up in a sudden and massive explosion: an asteroid, 40 m wide, had entered earth’s atmosphere and was breaking up in a multi-megaton burst. Although the asteroid itself didn’t make it to the ground, the shock wave and massive fireball that resulted destroyed 2,000 sq. km of forest, laying waste to the ground below. The Tunguska Event, as it’s called, took place in a remote area, so no human lives were lost. If the blast happened over Toronto, London or Shanghai, it would be another story.

Thousands of asteroids, most of them untracked, swarm around our planet; some are over 10 km wide. “Right now, the most probable amount of warning we’ll have for an asteroid impact is zero, because we don’t know where most of them are,” says Robert Jedicke, 46, a University of Hawaii astronomer originally from Niagara Falls, Ont. Jedicke is part of a team at UH’s Institute for Astronomy that’s working to change that. A new program, called Pan-STARRS, will combine the world’s most powerful asteroid-tracking telescope with the largest digital camera ever built. The first of four planned telescopes is set to begin its full scientific mission any day now. “In the past 200 years, we’ve discovered half a million asteroids,” he says. The first telescope alone “should find a comparable number in a single year.”

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