HOW’S THAT SPACE PROGRAM COMING ALONG? Tunguska explosion in 1908 caused by asteroid grazing Earth: A new theory explains the mysterious explosion in Siberia, scientists say, suggesting Earth barely escaped a far greater catastrophe. “If Khrennikov and colleagues are correct, then Earth had a lucky near-miss that morning. A direct impact with a 656 foot-wide (200 meter-wide) asteroid would have devastated Siberia, leaving a crater 2 miles (3 kilometers) wide. It would also have had catastrophic effects on the biosphere, perhaps ending modern civilization.”