Slashdot Mirror
Antarctic Craters Reveal Asteroid Strike
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."
← Back to Stories (view on slashdot.org)
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/
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.
"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?
Magnetism has nothing to do with the direction in which water flows in a drain. That would be the rotation of the planet.
Does the magnetic field being reversed actually affect anything important?
Yes.
Things like radiation reaching the planet's surface, stuff like that.
You can't take the sky from me...
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.
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.
It's called the Coriolis effect, but it's a myth that it affects the direction of water going down the drain. It does however influence large weather systems, so that in the northern hemisphere air circulates clockwise around high-pressure systems and counterclockwise around low-pressure. And obviously vice versa in the southern hemisphere.
This has some interesting effects, such as tornadoes tending to twist counterclockwise in the northern hemisphere, but clockwise in the southern. You probably won't have any use for knowing how it works, unless you're into meteorology, astrophysics, or possibly Trivial Pursuit.
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
However this report raises a lot of questions that it doesn't answer.
First of all, they seem to be talking about a single strike, but they first talk about "the crater" and then later "the holes" and "the craters." Are we talking about one crater or many? Did the person who wrote the article typo, or are the scientists being that unspecific?
Second of all, wasn't the Antarctic continent still near the south pole 780k years ago? That seems to mean that either the meteor hit at a very extreme angle, or it was _far_ out of the elliptic. In either case, it would be a very rare occurance.
On the other hand, magnetic reversals are _not_ a very rare occurance, they happen about once every 700,000 years. Why is he assuming that the very rare occurance caused the frequent and mostly regular occurance? It seems much more likely that it was just a coincidence. "There is no other explanation as to why this took place" yeah, and there is no other explanation for the other several _hundred_ nearly identical events either, because we haven't figured out why they happen yet! So is he proposing that Antarctica gets hit by a giant meteor about every 700k years like clockwork?
Finally exactly how "huge" are these craters, and what were the climatic conditions 780k years ago? If the climate was similar and Antarctica was near the south pole and covered with ice, wouldn't a "huge" strike have melted/dispersed quite a lot of the ice and caused ocean levels to rise?
This Space Intentionally Left Blank
Well, I'm off to filling my tub and experimenting for myself, thanks.
The best possible attitude toward science -- "show me!". Have fun in your tub!
Tubal-Cain smokes the white owl.
But on a serious note, whether or not this is an ordinary fluctuation is irrelevant in practical terms. If the magnetic field weakens enough to wreak havoc on our expectations (and that could affect much more than just compasses, of course), we should be paying attention to it, whether or not it is "insignificant" in terms of the larger time frame of the universe. Human beings ourselves are likely insignificant in terms of the history of the universe.
Say I give you a dot on a piece of graph paper. I tell you that this dot lies on a curve represented by the equation f(x)=y. Now accurately predict the path of this function. Do you have enough information to do anything? I don't think so.
For all we know our magnetic feild could have been at it's strongest ever 150 years ago and now it's leveling off to normal levels. Or perhaps it's dipping right before a major surge in magnetism. Maybe it's plumeting like a stone. The fact of the matter is we don't know anything, we simply don't have enough data. So if everyone is preparing for a time when Earth's magnetic field is extremely weak and then all of a sudden it shoots up to 200% and we're caught completely unprepared don't blame me.
Just because the magnetic field is getting slightly weaker or the Earth is getting slightly warmer doesn't mean this trend will just continue linearly and we're all in trouble. Nature is very unlinear, it tends to oscillate.
I don't mean that it's not a good idea to be cautious, but looking at such an insignificant portion of data and getting all worked up about it is just plain stupid.
It is too bad you know very little about science and the way it works. There is much more than 150 years of data available. Scientists really dislike being wrong and will usually wait until they have a "strong case" before making public claims or submitting papers to journals (the "cold fusion" mess proves how dumb carelessness (or stupidity) can be). The fact that you are modded "Insightful" (at least at this moment) indicates that you are not the only person who does not "get it."
1. The Bible is just a big book of stories. None of them are true.
2. Please don't ever reproduce.