D: Yaël, why are space scientists so worried that an asteroid might hit Earth. It probably won’t happen for a million years.
Y: Don, it happened in February, 2013.
Y: In 2013 a small asteroid about sixty feet across entered Earth’s atmosphere traveling at twelve miles per second over a populated area of central Russia. Frictional heat made it glow twice as bright as the sun, and people in its path suffered sunburn-like burns to their skin, and damaged their retinas if they looked directly at it.
D: Wow! What happened?
Y: The asteroid blew up nineteen miles over Russia’s seventh most populous city, Chelyabinsk. The explosion had a force thirty times greater than the atomic bomb dropped on Hiroshima. Chelyabinsk is the home of more than a million people.
D: Good grief! A city! Was anybody hurt?
Y: Over one thousand six hundred people were injured. People directly beneath the explosion were knocked off their feet. The shockwave blew out windows over two hundred square miles, and some buildings were damaged.
D: But isn’t this just a freak event unlikely to happen again?Y: Nope. In 1908 another asteroid exploded over the remote Tunguska region of Siberia with the energy of eight hundred Hiroshima bombs, knocking down forests over eight hundred square miles. At least three people died. Since then, there have been a number of other smaller explosions over remote areas. Chelyabinsk is the first time a city has been effected. The danger is very real. The world’s space agencies are mounting efforts to find ways to protect ourselves.