Every Asteroid Close Enough To Kill Us, Explained In 17 Minutes

Chelyabinsk. On the morning of February 15th, 2013, a rock about 20 meters across entered the atmosphere over southern Russia at roughly 19 kilometers per second. Nobody saw it coming. It approached from the direction of the Sun, which meant every telescope on Earth was blind to it, staring straight into the glare. There was no warning, no tracking, no name assigned to it in any database, because until the instant it began to burn, no one on the planet knew it existed. The object exploded about 30 kilometers above the city with the energy of roughly 500 kilotons, around thirty times the yield of the Hiroshima bomb. It never struck the ground as a single mass. Instead it detonated in the air, a phenomenon called an airburst, where the object is torn apart and vaporized by atmospheric pressure before impact, releasing its energy as a shockwave rather than a crater.