Posted on 11/09/2002 5:59:37 PM PST by Pokey78
Earth's magnetic field - the force that protects us from deadly radiation bursts from outer space - is weakening dramatically.
Scientists have discovered that its strength has dropped precipitously over the past two centuries and could disappear over the next 1,000 years.
The effects could be catastrophic. Powerful radiation bursts, which normally never touch the atmosphere, would heat up its upper layers, triggering climatic disruption. Navigation and communication satellites, Earth's eyes and ears, would be destroyed and migrating animals left unable to navigate.
'Earth's magnetic field has disappeared many times before - as a prelude to our magnetic poles flipping over, when north becomes south and vice versa,' said Dr Alan Thomson of the British Geological Survey in Edinburgh.
'Reversals happen every 250,000 years or so, and as there has not been one for almost a million years, we are due one soon.'
For more than 100 years, scientists have noted the strength of Earth's magnetic field has been declining, but have disagreed about interpretations. Some said its drop was a precursor to reversal, others argued it merely indicated some temporary variation in field strength has been occurring.
But now Gauthier Hulot of the Paris Geophysical Institute has discovered Earth's magnetic field seems to be disappearing most alarmingly near the poles, a clear sign that a flip may soon take place.
Using satellite measurements of field variations over the past 20 years, Hulot plotted the currents of molten iron that generate Earth's magnetism deep underground and spotted huge whorls near the poles.
Hulot believes these vortices rotate in a direction that reinforces a reverse magnetic field, and as they grow and proliferate these eddies will weaken the dominant field: the first steps toward a new polarity, he says.
And as Scientific American reports this week, this interpretation has now been backed up by computer simulation studies.
How long a reversal might last is a matter of scientific controversy, however. Records of past events, embedded in iron minerals in ancient lava beds, show some can last for thousands of years - during which time the planet will have been exposed to batterings from solar radiation. On the other hand, other researchers say some flips may have lasted only a few weeks.
Exactly what will happen when Earth's magnetic field disappears prior to its re-emergence in a reversed orientation is also difficult to assess. Compasses would point to the wrong pole - a minor inconvenience. More importantly, low-orbiting satellites would be exposed to electromagnetic batterings, wrecking them.
In addition, many species of migrating animals and birds - from swallows to wildebeests - rely on innate abilities to track Earth's magnetic field. Their fates are impossible to gauge.
As to humans, our greatest risk would come from intense solar radiation bursts. Normally these are contained by the planet's magnetic field in space. However, if it disappears, particle storms will start to batter the atmosphere.
'These solar particles can have profound effects,' said Dr Paul Murdin, of the Institute of Astronomy, Cambridge. 'On Mars, when its magnetic field failed permanently billions of years ago, it led to its atmosphere being boiled off. On Earth, it will heat up the upper atmosphere and send ripples round the world with enormous, unpredictable effects on the climate.'
It is unlikely that humans could do much. Burrowing thousands of miles into solid rock to set things right would stretch the technological prowess of our descendants to bursting point, though such limitations do not worry film scriptwriters. Paramount's latest sci-fi thriller, The Core - directed by Englishman Jon Amiel, and starring Hilary Swank and Aaron Eckhart - depicts a world beset by just such a polar reversal, with radiation sweeping the planet.
The solution, according to the film, to be released next year, involves scientists drilling into Earth's mantle to set off a nuclear blast that will halt the reversal.
Given that temperatures at such depths rival those of the Sun's surface, such a task would seem impossible - except, of course, in Hollywood.
Inertia is exactly what would cause a crustal displacement if they indeed exist. Every year 260 cubic miles of ice are deposited on Antarctica. All this weight is being concentrated on the axis of the earth's spin. Due to the uneven melting or uneven breaking off of chunks of ice, there will be more weight to one side of the earth's rotation axis. Eventually enough weight will accrue to suddenly fling toward the equator where it naturally wants to go. It takes just the crust with it since the crust sits on a liquid mantle and therefore can slide. The enertia of the earth's interior does not change, since it is only the crust that moves. It's like spinning a plate on a stick...get the plate a little off-center from the stick and it'll fling off the stick.
I make no claims as to whether the earth has "flipped" or not. I will point out that the earth is essentially a gyroscope. Gyroscopes are interesting things. We used them when I was on the subs. By orienting them along 3 axis you can maintained a stable platform. Along with accelerometers, you can calculate where you are based on measuring the acceleration effects along those 3 axis. But occasionally a gyro will "flip" (which is why you always have at least 2 intertial platforms, because when a gyro "flips" the platform will "crash".)
In any case, I think the earth could conceivably "flip" - no inertia is lost, the earth continues to spin quite happily. However, the atmosphere will not flip with the earth, so fairly quickly you will have some high relative wind velocities. Possibly very high. In which case, you want to be able to have a nice hole in the ground to crawl into for a while.
Here is a link on some basic gyro effects and simple gyro math: THE GYROSCOPE
A super-volcano in Yellowstone could ruin our whole day.
We'd have a better seat for the supernova explosion of Eta Carinae -- that would only fry the southern hemisphere with gamma rays, leaving those of us in North America relatively untouched.
Eta Carinae is one of the largest stars in our galaxy -- and one of the most unstable. It's also situated 8000 light years from us, "just down the street" in galactic terms.
It already puts out more than five million times the energy our Sun does. When it finally blows, it will for a time produce more energy than all the other stars in the galaxy combined. And we have a front row seat. Be sure to wear your 10,000,000 SPF sunscreen.
When will it go off? No way to tell, it's extremely unstable and unpredictable. But it has been growing strongly in intensity over the past ten years. If it keeps up, it'll be the second brightest star in the sky in just a few more years (right now it's quite dim in the sky due to its distance). The last time this happened (1841) it threw off a huge blast of matter that formed the "dumbbell" shaped nebula you see in the Hubbel photo above.
To give you an idea of the scale of that blast, the smallest features visible in that photo are each about the size of our entire solar system.
But there's no guarantee it'll only sputter this time. All we know is that it's definitely ramping up for another "event".
That thought crossed my mind, but... this seemed a bit of a stretch, even for "on average".
Let's just say, I'd like to apply similar math to the due date on my mortage payment :-)
Can you guys help me out here. I can never understand the rhetoric from the left
Now when a Republican President is voted in does:
A. Mother Earth immediately goes into overdirve to destroy us all?
B. The Evil Republicans Imediately work to destroy the earth by passing legislation that will kill all the wildlife and destroy the air and water?
C. The aura of produced by the sintly god-like benevolent Democrat President (who was voted out or against because of evil Reuplican voter fraud) fade, thus allowing A. to occur?(See A. Above) D. All of the above?
Oh, great. I have a hard enough time with the magnetic compass as it is now, let alone with eight poles...
How did that go, accelerate north, decelerate north-by-northwest..?
We really did win the midterm elections.
ROTFLOL!!!
And anyone with a complex understanding would know they're wrong...
I guess the dramatic effects of weather changes, wind patterns, etc haven't occured to someone as enlightened as yourself.
I guess this means Sandy Claws is a migratory establishment... Kinda sucks for them elves, having to move the toy factory and everything...
Pookie & ME
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