It was a day when the Earth was caught in a cosmic crossfire. The big rock came from the south, the smaller one from the east. They were unrelated objects, with different orbits, one the size of an apartment building, the other slimmer but with better aim.
The larger asteroid missed by 17,000 miles, as expected, but the Russian meteor stole the show Friday, fireballing across the Ural Mountains in spectacular fashion and exploding into fragments, creating a powerful shock wave that blew out windows, collapsed roofs and injured 1,200 people, mostly from broken glass.
It was surely the most thoroughly documented meteor in human history — captured by countless crack-of-dawn Russian drivers who own dashboard cameras.
The spectacle capped an extraordinary day for the planet. The object, which exploded over the industrial city of Chelyabinsk, caused the largest such impact in more than a century and was the first to inflict significant human casualties, with at least 48 victims hospitalized.
The asteroid that was supposed to show up Friday, the much-hyped 2012 DA14, passed by harmlessly, just as the experts had promised it would.
But they had no way of seeing the other rock heading toward Russia. The explanation from NASA scientists, when asked why they hadn’t spotted it, boiled down to two simple facts: It was small, and the sun was in their eyes.
“This was the largest object observed to hit the Earth since 1908,” said Margaret Campbell-Brown, an astronomer at the University of Western Ontario. That’s when another space rock exploded over Siberia, leveling 800 square miles of forest in what became known as the Tunguska event.
On Friday, a global network of sensors recorded the space rock’s object’s descent and revealed its stunning power. It measured about 50
feet wide, weighed more than a nuclear-powered submarine and screamed in at 40,000 miles per hour, said Campbell-Brown, who examined data from sonic sensors deployed by the Comprehensive Nuclear-Test-Ban Treaty Organization to detect nuclear detonations.
In its 30-second shallow-angle dive into the thickening atmosphere, the meteor shed energy equivalent to more than 20 Hiroshima-size atomic bombs. Most of that energy was dissipated many miles above the surface, and, in a sense, the atmosphere saved the day, preventing catastrophic damage from a major surface impact.
Initial estimates from Russian authorities sketched a much smaller and weaker object, but scientists say the nuclear-sensor network provides the best measure an incoming asteroid’s size and power.
Intense heat and pressure shattered the object into dozens of large pieces during its descent. Russian officials said they believed they had identified meteorite fragments on the ground 50 miles west of Chelyabinsk and had reports of pieces stretched out over another 75 miles.
Searchers also found a circular hole in the ice, 15 to 20 feet across, in a lake west of Chelyabinsk, and roped it off.
A transcript from a meeting of Russian emergency officials indicated about 3,000 buildings suffered damage.
The region’s governor, Mikhail Yurevich, said the biggest worry after the incident was the cold, with single-digit temperatures forecast overnight. “Our main task now is to preserve the heat in offices and homes where windows were shattered, to prevent the heating system from freezing,” he said.
Chelyabinsk, a city of 1.1 million people, has a high concentration of defense industries, and arsenals in its vicinity have occasionally exploded, but the meteor’s arrival appears not to have set off any. The roof of a zinc factory, however, came crashing down, triggering a spike in global zinc prices.
Russian President Vladimir Putin said, “Thank God no large objects fell in populated areas. However, there were still people who were injured.” The Interior Ministry, meanwhile, mobilized 10,000 police to deal with the incident.
The event immediately generated conspiracy theories. One
anti-Western member of Russia’s parliament, Vladimir Zhirinovsky, claimed that the meteor was actually a U.S. weapons test.
Scientists say the object was instead a small asteroid. NASA’s Bill Cooke said it flew in from the asteroid belt, a band of space rocks circling the sun beyond Mars and the source of all near-Earth asteroids.
History has recorded occasional injuries from meteorites, but the number hurt Friday is unprecedented, said Timothy McCoy, who studies meteorites at the Smithsonian’s National Museum of Natural History. “I can’t think of a burst this size over a city before,” he said.
Amateur footage showed at least two orange flashes as the meteor streaked over apartment buildings. A series of booms trailed the space rock. As it exploded, the meteor briefly blazed brighter than the sun.
And no one saw it coming.