Slashdot Mirror

← Back to Stories (view on slashdot.org)

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."

2 of 234 comments (clear)

  1. 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?

  2. 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