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Antarctic Craters Reveal Asteroid Strike

Posted by michael on from the rock-of-ages dept.

dhuff writes "Scientists using satellites have mapped huge craters under the Antarctic ice sheet caused by an asteroid as big as the one believed to have wiped out the dinosaurs 65m years ago."

25 of 234 comments (clear)

  1. Maybe....but I'm not buying it by Anonymous Coward · · Score: 5, Funny

    It could have been an explosion from several adolescent Predators when being overtaken by thousands of Aliens?

    1. Re:Maybe....but I'm not buying it by SirTalon42 · · Score: 3, Funny

      Lets find everyone named Shinji and kill him... FAST!

      I would rather the Angels win than he the world revolving around him...

    2. Re:Maybe....but I'm not buying it by hazem · · Score: 3, Informative

      My understanding is that tidal waves are seismic events that travel along the seafloor. They raise the water level only a few feet, and are essentially invisible until they hit shore and start climbing. Since icebergs float, it's not clear how they would suppress a shockwave happening below and around them.

      I'm not a specialist in this in any way at all. But maybe this is a good analogy:

      Smooth out 2 big comforters on your bed. Kneel on the side of the bed, and sweep your arm under the comforters from one end to the other. It's fairly easy because you only have to displace the comforters right around your arm.

      Now put a piece of cardboard as big as your bed between the two comforters. This simulates iceburgs. Now slide your arm through. It will be harder because your arm has to displace a larger amount of comforter as it moves along - the cardboard kind of spreads out the force/displacement that your arm is causing.

      That's the only thing I can think of.

  2. Curious by ValiantSoul · · Score: 3, Interesting

    "One thing that did happen at exactly the same time was the reversing of the Earth's magnetic field." Darn so the water hasn't always drained the same direction? Does the magnetic field being reversed actually affect anything important?

    1. Re:Curious by Anonymous Coward · · Score: 5, Funny

      Well....

      The compass industry will go South ;)

    2. Re:Curious by erick99 · · Score: 3, Insightful
      From GPSWorld.com

      Most electronic compasses are based on sensors that are magnetometers. A magnetometer is a device for measuring the intensity of one or more components of the Earth's magnetic field.

      I would think that a great deal of electronic devices would have a problem if the earths magnetic field suddenly "flipped."

      Cheers,

      Erick

      --
      http://www.busyweather.com/
    3. Re:Curious by Ralph+Wiggam · · Score: 5, Informative

      "Does the magnetic field being reversed actually affect anything important?"

      It doesn't matter what direction the field points, what matters is that there is a magnetic field around the Earth. During the time it takes for the field to flip, the field becomes very weak. That causes two problems. Some animals use the magnetic field for navigation. More importantly, the field is a shield protecting us from cosmic high energy particles. According to a story in the NY Times (covered on /.), Earth's magnetic field has weakened 10-15% since we started measuring 150 years ago. Maybe our grandkids will have to wear lead undies.

      -B

    4. Re:Curious by AstrumPreliator · · Score: 3, Insightful

      According to a story in the NY Times (covered on /.), Earth's magnetic field has weakened 10-15% since we started measuring 150 years ago. Maybe our grandkids will have to wear lead undies.

      Then again it might just be an insignificant fluctuation that happens every billion years or so. We have 150 years worth of data, the Earth is billions of years old, I don't think we're qualified to make assumptions.

    5. Re:Curious by Ralph+Wiggam · · Score: 3, Insightful

      Or course we don't have enough data. That's why I made a joke about lead undies and didn't declare the world was ending. The little data we have indicates that the decrease in field strength is accelerating. 10% is a significant drop. This is something we need to keep an eye on and take seriously.

      -B

    6. Re:Curious by oquigley · · Score: 5, Interesting

      The Earths Magnetic field keeps all kind of nasty radiation from hitting the surface.
      So it's always been a bit of a puzzle why there's no correllation between magnetic reversals (where the magnetic field weakens, fades, then reappears with swapped poles) and mass extinctions.
      After all, one would think that floods of radiation washing across the Earths surface would be unhealthy, no?

      But now it appears that when the magnetic field weakens, the solar wind induces a magnetic field in the ionosphere that's pretty much as effective at stopping high energy particles and cosmic rays as is the original field.

      Here's an article about it in New Scientist from a few months ago.
      New Scientist


  3. Well now... by reezle · · Score: 4, Interesting

    I'd like to think we could do something about this problem, but I wonder if any technology we have could alter the course of an asteroid large enough to be a problem. Do we even have a prototype of something like a fusion rocket that could potentialy move the hundreds (thousands/millions) of tons of mass that these big rocks have?

    Have the nuk-lear worryworts made sure that we haven't even researched the possibilities? Best I've ever seen is the occasional schematic of an orion-type starship from decades ago. Screw Ion-Drives. Let's give some money to the big engines...

    1. Re:Well now... by dyfet · · Score: 4, Interesting

      I believe this very question was seriously studied back in the late 60's and early 70's in project Icarus. I think their conclusion at the time was that the best option was to load up a Saturn V with as many nukes as possible, aim carefully, and just hope for the best...

    2. Re:Well now... by lommer · · Score: 4, Interesting

      Yes, they do have to be timed perfectly. However, in the nuclear explosion world, perfect timing is what it's all about. One of the primary difficulties in constructing a nuclear warhead is timing all the conventional explosives that compound the critical mass of plutonium (or uranium) to produce the nuclear explosion. The science is so precise that they have to account for the time delay it takes the electricity to travel down wires that are only meters long, let alone the rates at which the shockwave propagates through the conventional explosive - all of which must be correct to within thousandths of a second. Add another layer of complexity for hydrogen bombs.

      So yes, they would have to time them perfectly, but that wouldn't be too difficult as it's a problem they've already figure out how to solve when constructing the devices in the first place.

    3. Re:Well now... by jadavis · · Score: 4, Interesting

      Yup. Even an individual nuke requires very precise timing so that it implodes evenly. If not, it will start to break apart and never achieve the pressure required to detonate. Even when a nuke does detonate it only gets a moderate yield (I think "fat man" was about 15% yield) because it breaks itself apart so fast.

      --
      Social scientists are inspired by theories; scientists are humbled by facts.
  4. No layer of dust? by rde · · Score: 4, Interesting

    Quoth the good professor:
    The extraordinary thing about this meteor strike is that it appeared to do so little damage. Unlike the dinosaur strike there is no telltale layer of dust that demonstrates the history of the event.

    It ploughs through millions of tonnes of ice and snow, then leaves no layer of dust... d'you think it might have, I dunno, melted or something?

    More information at The Scotsman, btw.

  5. Stay away... by SteamyMobile · · Score: 5, Funny

    If they find pyramids under there, stay away from them.

  6. Interception by panurge · · Score: 4, Insightful
    Perhaps this really is the time for NASA, the ESA, and Russia to pool their efforts to find a way of detecting, intercepting and deflecting comets and wandering asteroids that present a threat. The European Quijote Project seems to be a step in the right direction(as well as having a very witty title).

    Obviously, statistically the chance of an individual being killed by a major meteor strike is fairly low, perhaps lower than that of being killed in a terrorist attack and much lower than that of being killed on the roads. But it's the meteor strike that has the potential to kill perhaps 99% of the human race, and this latest evidence seems to suggest that the frequency of such impacts is higher than expected.

    --
    Panurge has posted for the last time. Thanks for the positive moderations.
  7. impact reversing magnetic field? doubtful by Lobachevsky · · Score: 5, Interesting

    I don't dispute Hans' rigor in studying the issue, but how can the correlation of the impact and the magnetic field reversing lead to the conclusion the impact caused the reversal?

    And why even compare this 780K yr old impact to what might've done the dinosaurs in 65m yrs ago? It just would confuse people with poor reading skills (*cough* slashdot readers) and lead them to associate this 780K yr old impact with the extinction of the dinasaurs.

    Also, the article attemps to explain why the 65m yr old impact would've caused climactic change whereas the 780k yr old impact would not -- I didn't quite understand their argument of why the older impact caused dust clouds leading to extinction while the newer impact did not -- was it because of the composition of ice vs rock?

  8. 65 milli years ago? by Anonymous Coward · · Score: 5, Funny

    That's 24 days ago.

    The dinosaurs were wiped out on July 28 2004?

  9. You really are missing something...... by TheAxeMaster · · Score: 5, Insightful

    a lot of people believe that the 65m impact was centered over land NOT covered by ice and snow, as in the central point in which all current continents used to be connected (pangea).

    That impact would have crushed mountains and created enormous amounts of dust from them. The 780k impact hit a huge block of ice and snow, i.e. no dust to scatter in the first place. I really doubt it would have affected any land life at all, antarctica being so far from land inhabited by anything more than penguins and stuff. Ocean life probably got pretty roughed up at least close to the impact.

    1. Re:You really are missing something...... by davidsyes · · Score: 3, Interesting

      Or, was it just "a close shave"?

      Don't we pass through an asteroid belt about twice a year? I seem to remember something on Discovery Channel or on an astronomy site that named the belts. I'll revisit the sites, but in the meantime... Aren't there all sorts of odds (in favor of nature/against human populations) that could see us or the Earth being hit once in a while more frequently than we've recorded or claimed? If not, then...

      What are the chances (hi or lo) that we pass through some metallic or iced or similar matter that envelops or fries all the satellites in orbits? I'll concede that it MIGHT NOT happen in our lifetimes, but if it were GOING to happen by fluke or freak of nature, what kind of circumstances would be needed but not rip up large swaths of ground, and not rip away the breathable atmosphere?

      And, if we suffered such a "scrape", what would be needed to make orbital space unusable for say, 5 years, but, again, without the solar event tearing up the terra firma? Would passing through a sort of cometary corona or ice tail for about 6 or 7 days be enough? (And, let's assume or posit that no more than 20% of the the clean water and no more than 30% of the food production are affected.)

      Would anyone speculate on the confluence of events needed?

      David Syes

      --
      Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"
  10. Re:Parent is ignorant or trolling? Hard to tell. by Aardpig · · Score: 4, Informative

    Magnetism has nothing to do with the direction in which water flows in a drain. That would be the rotation of the planet.

    And for all reasonable-sized drains (such as the ones you have at the bottom of your bathtub), the Earth's rotation has a completely-negligible effect on the outflow. The notion that the Coriolis force causes water to drain in opposite directions, in the Northern and Southern hemispheres, is a fallacy.

    To see why this is so, consider the so-called Rossby radius of deformation , defined as the ratio between wave speed and rotation frequency. This quantity is the length scale at which the Coriolis force begins to have an appreciable effect on disturbances in a fluid in a rotating system. Plugging in the appropriate values for water waves in a bathtub on the rotating Earth, you find a Rossby radius of around 20km. This is four orders of magnitude larger than the scale of the bathtub, indicating that the influence of the Coriolis force on draining water will be almost non-existant.

    --
    Tubal-Cain smokes the white owl.
  11. Location? by Anonymous Coward · · Score: 3, Insightful
    The article doesn't say where in Antartica or even what conference. After much searching I found this which says,
    Using satellite technology to observe the Antarctic gravity field from thousands of miles above the earth, the international team of geophysicists found evidence of many large meteorite impact sites across the entire continent. Presenting their research to the International Geographical Congress in Glasgow this week, the results of the imaging revealed that the sites extend from the Ross Sea in the vicinity of the Pacific Ocean, to the Weddell Sea south of the Atlantic Ocean. However, those wishing to make a journey to Antarctica to see for themselves the craters left by the interstellar objects will be disappointed.
    That sounds like most of West Antarctica.
  12. Homo Erectus was there by oquigley · · Score: 4, Interesting

    Wow! Only 780 thousand years ago?
    At that point our hominid ancestors were strolling around southern Africa. By then we had stone tools and the occasional use of fire. That's really recent in a hominid lineage that goes back, what 6 million years? They lived through a 3-7 kilometer asteroid impact! Can you imagine?
    Good thing it didn't land a few thousand miles to the north...

  13. Asteroids? by feidaykin · · Score: 3, Funny

    Everyone remain calm. I spent countless hours in arcades preparing for such an impact. That's the real reason the dinosaurs died: they didn't have arcades.

    --

    "To confine our attention to terrestrial matters would be to limit the human spirit." -Stephen Hawking