Lebanon Reporter

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
  • Church's denied request for National Guard visit draws national attention

    A Missouri church finds itself in the middle of a media storm after the Missouri National Guard, citing short notice and time constraints, was not able to fulfill a request last week to appear at the church’s vacation Bible school.

    August 1, 2014

  • Screen Shot 2014-07-28 at 2.21.22 PM.png VIDEO: Dog 'faints' from excitement of seeing owner

    A reunion between a Pennsylvania woman who had been living overseas for two years and her pet schnauzer has gone viral, garnering nearly 20 million views on YouTube.

    August 1, 2014 1 Photo

  • Why a see-through mouse is a big deal for scientists

    A group of Caltech researchers announced in Cell Thursday their success in making an entire organism transparent. Unfortunately, this isn't any kind of "Invisible Man" scenario: The organism in question is a mouse, and the mouse in question is quite dead.

    July 31, 2014

  • Screen Shot 2014-07-31 at 2.12.55 PM.png VIDEO: Five-year-old doesn't want her brother to grow up

    Sadie, an adorable 5-year-old from Phoenix, wants her brother to stay young forever, so much so that her emotional reaction to the thought of him getting older has drawn more than 10 million views on YouTube.

    July 31, 2014 1 Photo

  • lockport-police.jpg Police department turns to Facebook for guidance on use of 'negro'

    What seems to be a data entry mistake by a small town police department in western New York has turned into a social media firestorm centered around the word "negro" and whether it's acceptable to use in modern society.

    July 31, 2014 3 Photos

  • The virtues of lying

    Two computational scientists set out recently to simulate the effects of lying in a virtual human population. Their results, published in the Proceedings of the Royal Society B, show that lying is essential for the growth of a cohesive social network.

    July 31, 2014

  • Sunburn isn't the only sign of summer that can leave you itchy and blistered

    You've got a rash. You quickly rule out the usual suspects: You haven't been gardening or hiking or even picnicking, so it's probably not a plant irritant such as poison ivy or wild parsnip; likewise, it's probably not chiggers or ticks carrying Lyme disease; and you haven't been swimming in a pond, which can harbor the parasite that causes swimmer's itch.

    July 30, 2014

  • Survey results in legislation to battle sexual assault on campus

    Missouri U.S. Sen. Claire McCaskill joined a bipartisan group of senators Wednesday to announce legislation that aims to reduce the number of sexual assaults on college campuses.

    July 30, 2014

  • An alarming threat to airlines that no one's talking about

    It's been an abysmal year for the flying public. Planes have crashed in bad weather, disappeared over the Indian Ocean and tragically crossed paths with anti-aircraft missiles over Ukraine.

    July 30, 2014

  • Sharknado.jpg Sharknado 2 set to attack viewers tonight

    In the face of another "Sharknado" TV movie (the even-more-inane "Sharknado 2: The Second One," premiering Wednesday night on Syfy), there isn't much for a critic to say except to echo what the characters themselves so frequently scream when confronted by a great white shark spinning toward them in a funnel cloud:
    "LOOK OUT!!"

    July 30, 2014 1 Photo

Featured items
Click below to browse and order photos


Photos from June 2014

Twitter Updates
Follow us on twitter
AP Video
Renewed Violence Taking Toll on Gaza Residents 2 Americans Detained in North Korea Seek Help US Employers Add 209K Jobs, Rate 6.2 Pct House GOP Optimistic About New Border Bill Gaza Truce Unravels; Israel, Hamas Trade Blame Raw: Tunisia Closes Borders With Libya Four Rescued From Crashed Plane Couple Channel Grief Into Soldiers' Retreat WWI Aviation Still Alive at Aerodrome in NY Raw: Rescuers at Taiwan Explosion Scene Raw: Woman Who Faced Death Over Faith in N.H. Clinton Before 9-11: Could Have Killed Bin Laden Netanyahu Vows to Destroy Hamas Tunnels Obama Slams Republicans Over Lawsuit House Leaders Trade Blame for Inaction
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.
Hyperlocal Search
Premier Guide
Find a business

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