Russian Asteroid Explosion and Past Impactors Paint a Potentially Grim Future for Earth

The recent meteor explosion over Chelyabinsk brought to the forefront a topic that has worried astronomers for years, namely that an impactor from space could cause widespread human fatalities.  Indeed, the thousand+ injured recently in Russia was a wake-up call. Should humanity be worried about impactors? “Hell yes!” replied astronomer Neil deGrasse Tyson to CNN’s F. Zakharia [...]