February 16, 2013
Despite coming to the planet without warning, the meteorite that crashed near Chelyabinsk, Russia, on Friday is the largest object to strike Earth in more than a century and the most widely documented such incident ever, NASA and Chicago experts said.
Thousands of people near the central Russian city witnessed the object streak across the sky and heard the sonic booms as it entered Earth's atmosphere and broke apart. More than 1,100 people were injured, most by shattering glass. No one was killed, authorities said, but residents described feeling panic as a power greater than a nuclear bomb's was unleashed near the city of 1.1 million, 950 miles east of Moscow.
"I was driving to work. It was quite dark, but it suddenly became as bright as if it were day," said Viktor Prokofiev, 36, a resident of Yekaterinburg in the Ural Mountains. "I felt like I was blinded by headlights."
Before 9:30 a.m. local time, the fireball streaked across the horizon, its long white trail visible from at least 125 miles away.
"I was standing at a bus stop, seeing off my girlfriend," said Andrei, a Chelyabinsk resident who did not give his last name. "Then there was a flash, and I saw a trail of smoke across the sky and felt a shock wave that smashed windows."
Some Russian scientists initially estimated the object's weight at 10 tons. But later Friday, preliminary size estimates from North American astronomers, using data from sonic measuring stations, put the object's pre-breakup weight at 7,000 tons and perhaps 40 to 50 feet across, according to Nature.com and NASA. One observed impact showed a hole more than 20 feet across in a frozen Russian lake.
"If that (weight) really is true, it probably is one of the biggest impacts, if not the biggest impact, since the 1908 Tunguska blast over Siberia," said Mark Hammergren, an astronomer at the Adler Planetarium and a specialist in asteroids and meteoroids. That event, believed to have been caused by the shock wave from a meteorite or comet breaking up, knocked down some 800 square miles of Siberian forest.
Friday's strike came hours before a closely monitored asteroid, 150 feet across, passed within 17,200 miles of Earth, leading to speculation that the events might be related. Their relative trajectories make it clear that they were not, scientists said.
"It's a ridiculous cosmic coincidence," Hammergren said. "Like everyone else I was totally caught by surprise. Today I was expecting the big astronomy story to be the flyby of an asteroid, not the impact of a large meteor."
Hundreds captured the extraterrestrial visitation on video, largely because of the Russian custom of mounting cameras on dashboards to fight insurance fraud, said Terry Boudreaux, a North Shore collector of meteorites who has worked with the Field Museum on its collection.
Prior to the Chelyabinsk meteorite — not an official name yet, but they are typically named after nearby geography — there have been "maybe 20" videos of meteorites entering Earth posted to the Internet, Boudreaux said. Now there are apparently hundreds of Friday's event on YouTube and the like, making it the talk of workplaces and cable news channels.
The previous champion for being caught on tape was the Peekskill meteorite of 1992, witnessed across the East Coast as it streaked through the atmosphere before a chunk crashed into a car trunk in Peekskill, N.Y. "That one came down on a Friday night during homecoming season," said Hammergren, so people at football games had video cameras ready.
Most U.S. newscasts Friday repeated NASA's assertion that the meteorite was unrelated to the asteroid passing and emphasized that the injuries came from broken glass, not from the meteor strike.
But the media did struggle, at times, to maintain detachment. Said a Fox News Channel anchor about the meteorite, "You wonder if there are any more coming."
Not likely, scientists said.
Meteorite falls do not come in barrages and are randomly distributed across the Earth, with most, naturally, occurring in the oceans or other uninhabited places.
Meteor, incidentally, is the term for the space phenomenon, while a meteoroid is a meteorite still in space, said Philipp Heck, the Field's curator of meteorites. A meteoroid is a smaller asteroid.
But while asteroids are big enough to be tracked, meteoroids, being smaller and dark against the backdrop of space, are much tougher. If people were looking in the right place, they might have seen the Russian meteorite a day or two in advance, said Hammergren, but few are looking.
"There are more people working at an average McDonald's franchise than are employed in asteroid surveys," he said. "This is a reminder to us as a society that we are connected to the solar system at large, that asteroid impacts do occur."
It is too soon to know the origin or composition of the Russian meteorite, the Chicago scientists said. Its value to science will depend on whether it is from a planet or moon or the asteroid belt, and what minerals comprise it.
While meteorites of considerable size fall to Earth every few years, said Heck, this one has extra value. Its high-profile entry makes pieces from it worth six or more times those from an "ordinary" specimen, Boudreaux said.
And the hunt for those pieces began almost immediately. Recently returned from the annual Tucson Gem and Mineral Show, Boudreaux, a 52-year-old retired health care executive, said he was on the phone in pre-dawn hours Friday with fellow collectors who were still at the Arizona show, discussing the Russian event.
One of them, he said, is "the Indiana Jones of the meteorite world" — Mike Farmer, an American.
Farmer told Boudreaux about a Russian meteorite dealer leaving in the middle of the night and heading home to try to find some of this space rock.
"Literally this guy left with his backpack and went to a plane to get back to Moscow," Boudreaux said. "He told (Farmer), 'I'm out. See ya.'"
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