On the morning of February 15, 2013, a meteorite the size of a semi-trailer rocketed from the direction of sunrise and exploded in a fireball over the city of Chelyabinsk, Russia. The meteorite briefly glowed brighter than the sun itself, and exploded with 30 times more energy than the bomb that destroyed Hiroshima, detonating about 14 miles (22 kilometers) above the Earth’s surface. The explosion shattered the windows of more than 7,000 buildings, temporarily blinded pedestrians, caused instant ultraviolet burns and injured more than 1,600 people. Fortunately, it resulted in no known deaths.
What the observatories did not detect
The Chelyabinsk meteorite is believed to be the largest natural space object to enter Earth’s atmosphere in more than 100 years. However, no observer on Earth expected this to happen. Arriving from the direction of the sun, the rock remained hidden in our greatest blind spot, until it was too late.
Fortunately, such events are uncommon. Boulders the size of the Chelyabinsk meteorite — about 66 feet (20 meters) across — penetrate Earth’s atmosphere once every 50 to 100 years, the European Space Agency (ESA) estimates. Larger asteroids strike less frequently. So far, astronomers have mapped the orbits of more than 33,000 near-Earth asteroids, and found that none of them pose a threat to hitting our planet during at least the next century.
Can we predict the danger of asteroids?
But you can’t count the risk of an asteroid you can’t see, and there are untold thousands of them, including some large enough to destroy cities and possibly trigger mass extinction events, moving on unknown paths around our star, experts said. Live sciences. It’s a harsh reality that has astronomers worried about the potential consequences and eager to find as many hidden asteroids in our solar system as possible. Once we know about them, killer asteroids can either be monitored and removed if necessary, or, if all else fails, residents can be warned to move elsewhere to avoid mass casualties.
“The most problematic object is the one you know nothing about,” said Amy Mainzer, a professor of planetary science at the University of Arizona and the principal investigator on two NASA asteroid-hunting missions. “If we can find out what’s out there, we can get a much better estimate of the true risk.”
