Batesville Herald Tribune, Batesville, Indiana

Community News Network

November 6, 2013

Hazardous asteroids may be more numerous than previously thought, scientists say

There are scads of building-size, potentially hazardous asteroids lurking in Earth's immediate neighborhood, and they may be colliding with the planet 10 times more often than scientists have previously believed, according to a new study published Wednesday that examined the airburst of a 25-million-pound asteroid earlier this year near the Russian city of Chelyabinsk.

Three studies released Wednesday, two in the journal Nature and one in the journal Science, have provided the most detailed description and analysis of the dramatic event on the morning of Feb. 15.

Scientists now estimate the diameter of the object at just a hair under 20 meters, or about 65 feet. Undetected by astronomers, the rock came out of the glare of the sun and hit the atmosphere at 43,000 miles per hour.

As it descended through the atmosphere, it broke into fragments, creating a series of explosions with the combined energy of about 500 kilotons of TNT, making it more than 30 times more powerful than the atom bomb that destroyed Hiroshima in 1945, although the energy in this case was spread out over a much broader area.

The shock wave blew out windows in nearly half the buildings in Chelyabinsk. It knocked people off their feet; dozens were sunburned by the blinding flash, which at its peak was 30 times brighter than the sun. About 1,200 people were hurt, most by broken and flying glass, but no one was killed.

One chunk the size of love seat landed in frozen Chebarkul Lake, leaving a circular hole, as if shot with a bullet from space. That fragment, which weighed about 1,900 pounds, was retrieved months later, breaking into several pieces in the process. Thousands of smaller pieces have also been recovered.

The scientific investigation relied to a great degree on video imagery obtained by "dashcams," the cameras Russian drivers often use to document car crashes and potentially abusive law enforcement. Scientists visited 10 locations where the footage had been taken by stationary cameras, and used landmarks to create a map of the asteroid's trajectory. The shock wave damage propagated perpendicularly to the path of the rock.

"It's incredible how well-documented all this is," said Peter Jenniskens, a meteor astronomer at the SETI Institute and a co-author of the paper in Science.

Taken together, the new information on Chelyabinsk does not suggest that the sky is falling (no one has ever been killed by an asteroid in all of recorded human history). But it may shift the overall risk profile of asteroids, making Chelyabinsk-size events look more probable.

That's the conclusion of Peter Brown, a professor at Western University in London, Ontario, who reexamined decades of data compiled by scientific and military sensors. The scientific orthodoxy said that a Chelyabinsk-size event ought to happen every 140 years or so, but Brown saw several such events in the historical record.

Famously, a large object exploded over the Tunguska region of Siberia in 1908. But there have been less-heralded impacts, including one on Aug. 3, 1963, when an asteroid created a powerful airburst off the coast of South Africa.

"Any one of these taken separately I think you can dismiss as a one-off. But now when we look at it as a whole, over a hundred years, we see these large impactors more frequently than we would expect," said Brown, whose paper appeared in Nature.

Most rocks that size have yet to be identified, and it would be difficult and expensive to find them and calculate their trajectories, Brown said. But this could boost efforts already underway to create early-warning systems for Chelyabinsk-class impactors that are just a few days away, he said.

The paper in Science hypothesized that the Chelyabinsk asteroid is a piece of "rubble" from a larger body that had been broken apart by tidal forces from an earlier near-Earth encounter.

"The rest of that rubble could still be part of the near-Earth object population," the authors wrote.

 

1
Text Only
Community News Network
  • Police chief resigns over racial slur repost to Facebook

    A repost on his personal Facebook page of a racially-charged comment by the original poster of a comedy video has forced the police chief of an Oklahoma city to resign his office.

    August 21, 2014

  • Does Twitter need a censor?

    Twitter decided last year to make images more prominent on its site. Now, the social network is finding itself caught between being an open forum and patrolling for inappropriate content.

    August 21, 2014

  • sleepchart.jpg America’s sleep-deprived cities

    Americans might run on sleep, but those living in the country's largest cities don't appear to run on much.

    August 20, 2014 1 Photo

  • Who should pay for your kids ACT?

    Thirteen states paid for 11th-grade students in all public high schools to take the ACT college admission test this year, with several more planning to join them in 2015.

    August 20, 2014

  • Pets.jpg Why do people look like their pets?

    As much as we might quibble over the virtues and vices of Canis domesticus, however, and over whether human nature is any better or worse than dog nature, even dog fanciers don't usually want to look like a dog.

    August 20, 2014 1 Photo

  • Ice bucket challenge trending up

    Internet trends are a dime a dozen these days. Everything from Tebowing to planking to the cinnamon challenge can cause a wave of social media activity that can last for weeks before fizzling out.

    August 19, 2014

  • Africa goes medieval in its fight against Ebola

    As the Ebola epidemic claims new victims at an ever-increasing rate, African governments in Sierra Leone, Guinea and Liberia have instituted a "cordon sanitaire," deploying troops to forcibly isolate the inhabitants in an area containing most of the cases.

    August 18, 2014

  • Democrat? Republican? There's an app for that

    If you're a Republican, you might want to think twice before buying Lipton Iced Tea, and forget about Starbucks coffee. If you're a Democrat, put down that Reese's Peanut Butter Cup, and throw away the cylinder of Quaker Oats in your pantry.

    August 18, 2014

  • Five myths about presidential vacations

    In the nuclear age, presidents may have only minutes to make a decision that could affect the entire world. They don't so much leave the White House as they take a miniature version of it with them wherever they go.

    August 15, 2014

  • Can 6 seconds launch a career? A generation of Vine stars sure hopes so.

    A year ago, Shawn Mendes filmed himself singing a tentative acoustic cover of the Justin Bieber song "As Long as You Love Me" and put the results on Vine. He wasn't expecting much response. "I didn't really want anything to happen; I just kind of wanted to see what people would think," says Mendes, 16. "I posted that first Vine and woke up the next morning with 10,000 followers. That was pretty cool."

    August 14, 2014

Featured Ads
AP Video
NYC Doctor-in-chief Seeks Community Approach Indonesian Police Fire Tear Gas at Protesters Raw: Shots Fired in Liberian Shantytown DOJ, Bank of America Reach Record Settlement Raw: Cubavision Airs Images of Fidel Castro Raw: Grief After Deadly Airstrikes in Gaza Officer Who Pointed Gun at Protesters Suspended Kathy Griffin Challenges Minaj to 'a Booty Off' Johnson: Six Arrests, No Tear Gas in Ferguson Raw: Rescue, Relief Efforts at Japan Landslide Cadavers, a Teen, and a Medical School Dream Raw: Woman Escorted From Ferguson Protests California Drought Stings Honeybees, Beekeepers Officer Who Pointed Gun at Protesters Suspended Holder Hopes to Bring Calm to Ferguson US Mission to Rescue Hostages in Syria Failed Manfred, Torre and MLB Take Ice Bucket Challenge Bank of America Reaches Record $17B Settlement Holder Reassures Ferguson Community With Visit GlobalPost CEO Remembers Foley As a Brave Man
Seasonal Content
Hyperlocal Search
Premier Guide
Find a business

Walking Fingers
Maps, Menus, Store hours, Coupons, and more...
Premier Guide
Parade
Magazine

Click HERE to read all your Parade favorites including Hollywood Wire, Celebrity interviews and photo galleries, Food recipes and cooking tips, Games and lots more.
Facebook