I’ve been avoiding this story (Magnetic polar shifts cause massive global super storms) for awhile, hoping it would simply die, but people keep asking me about it, and I see it appearing on other blogs, so I suppose I’ll have to address it. Mainly what I want to do is present facts about it and let readers make up their own minds.
There has been a lot of worry and hype on this subject. Part of it is fueled by the silly “2012” thing. Some it has been fueled by people who had been primed for “space storms” in solar cycle 24, such as in this Fox News video:
Many people still haven’t got the memo that solar cycle 24 is now forecast by NASA (after a number of forecast reductions) to be about as quiet as the Dalton Minimum, with a peak sunspot count of 59 in their latest forecast. They hear that the protective Earth’s magnetic field may flip/deplete from one source, remember the hype over the upcoming solar cycle, and worry that we are going to get toasted. I assure you, we will, when the sun turns into a red giant a couple billion years from now, but let’s not worry about that.
In the meantime, yes, at some point the Earth’s magnetic field will flip. Compasses will point south instead of North. According to the best science we have this happens frequently on Earth (in the scale of geologic time). And, as we know, the sun’s magnetic field appears to reverse its polarity on the advent of each new solar cycle, about every 11 years. The sun doesn’t wink out or get stormy when this happens, nor can we as humans detect any earthly change when this occurs. It’s essentially imperceptible to us.
As for earth, it’s magnetic field also flips, but not nearly as often. About every 200,000-250,000 years. The last one occurred 780,000 years ago, so the period is not constant. This is to be expected in a chaotic system. Below, see the magnetic record timeline as derived from rocks:
More on the magnetic timeline here. Looking at the long term record, magnetic field reversals are rather common. So, as far as Earth goes, it is “business as usual”. It probably would say: “Nothing to see here, move along.” if asked. I’ll point out that life continued through all of this. And, as far as I know, no scientist has linked extinctions to reversals. The Wikipedia article has this to say:
Because the magnetic field has never been observed to reverse by humans with instrumentation, and the mechanism of field generation is not well understood, it is difficult to say what the characteristics of the magnetic field might be leading up to such a reversal.
Some speculate that a greatly diminished magnetic field during a reversal period will expose the surface of the Earth to a substantial and potentially damaging increase in cosmic radiation. However, Homo erectus and their ancestors certainly survived many previous reversals, though they did not depend on computer systems that could be damaged by large coronal mass ejections.
There is no uncontested evidence that a magnetic field reversal has ever caused any biological extinctions. A possible explanation is that the solar wind may induce a sufficient magnetic field in the Earth’s ionosphere to shield the surface from energetic particles even in the absence of the Earth’s normal magnetic field. Another possible explanation is that magnetic field actually does not vanish completely, with many poles forming chaotically in different places during reversal, until it stabilizes again.
There’s a NASA story on the wandering magnetic North pole from 2003 that is instructive, I’m repeating part of it below:
===============================================================
Scientists have long known that the magnetic pole moves. James Ross located the pole for the first time in 1831 after an exhausting arctic journey during which his ship got stuck in the ice for four years. No one returned until the next century. In 1904, Roald Amundsen found the pole again and discovered that it had moved–at least 50 km since the days of Ross.
The pole kept going during the 20th century, north at an average speed of 10 km per year, lately accelerating “to 40 km per year,” says Newitt. At this rate it will exit North America and reach Siberia in a few decades.
Keeping track of the north magnetic pole is Newitt’s job. “We usually go out and check its location once every few years,” he says. “We’ll have to make more trips now that it is moving so quickly.”
Earth’s magnetic field is changing in other ways, too: Compass needles in Africa, for instance, are drifting about 1 degree per decade. And globally the magnetic field has weakened 10% since the 19th century. When this was mentioned by researchers at a recent meeting of the American Geophysical Union, many newspapers carried the story. A typical headline: “Is Earth’s magnetic field collapsing?”
Probably not. As remarkable as these changes sound, “they’re mild compared to what Earth’s magnetic field has done in the past,” says University of California professor Gary Glatzmaier.
Sometimes the field completely flips. The north and the south poles swap places. Such reversals, recorded in the magnetism of ancient rocks, are unpredictable. They come at irregular intervals averaging about 300,000 years; the last one was 780,000 years ago. Are we overdue for another? No one knows.
Left: Magnetic stripes around mid-ocean ridges reveal the history of Earth’s magnetic field for millions of years. The study of Earth’s past magnetism is called paleomagnetism. Image credit: USGS. [more]
According to Glatzmaier, the ongoing 10% decline doesn’t mean that a reversal is imminent. “The field is increasing or decreasing all the time,” he says. “We know this from studies of the paleomagnetic record.” Earth’s present-day magnetic field is, in fact, much stronger than normal. The dipole moment, a measure of the intensity of the magnetic field, is now 8 × 1022 amps × m2. That’s twice the million-year average of 4× 1022 amps × m2.
To understand what’s happening, says Glatzmaier, we have to take a trip … to the center of the Earth where the magnetic field is produced.
At the heart of our planet lies a solid iron ball, about as hot as the surface of the sun. Researchers call it “the inner core.” It’s really a world within a world. The inner core is 70% as wide as the moon. It spins at its own rate, as much as 0.2° of longitude per year faster than the Earth above it, and it has its own ocean: a very deep layer of liquid iron known as “the outer core.”
Right: a schematic diagram of Earth’s interior. The outer core is the source of the geomagnetic field.
Earth’s magnetic field comes from this ocean of iron, which is an electrically conducting fluid in constant motion. Sitting atop the hot inner core, the liquid outer core seethes and roils like water in a pan on a hot stove. The outer core also has “hurricanes”–whirlpools powered by the Coriolis forces of Earth’s rotation. These complex motions generate our planet’s magnetism through a process called the dynamo effect.
Using the equations of magnetohydrodynamics, a branch of physics dealing with conducting fluids and magnetic fields, Glatzmaier and colleague Paul Roberts have created a supercomputer model of Earth’s interior. Their software heats the inner core, stirs the metallic ocean above it, then calculates the resulting magnetic field. They run their code for hundreds of thousands of simulated years and watch what happens.
What they see mimics the real Earth: The magnetic field waxes and wanes, poles drift and, occasionally, flip. Change is normal, they’ve learned. And no wonder. The source of the field, the outer core, is itself seething, swirling, turbulent. “It’s chaotic down there,” notes Glatzmaier. The changes we detect on our planet’s surface are a sign of that inner chaos.
They’ve also learned what happens during a magnetic flip. Reversals take a few thousand years to complete, and during that time–contrary to popular belief–the magnetic field does not vanish. “It just gets more complicated,” says Glatzmaier. Magnetic lines of force near Earth’s surface become twisted and tangled, and magnetic poles pop up in unaccustomed places. A south magnetic pole might emerge over Africa, for instance, or a north pole over Tahiti. Weird. But it’s still a planetary magnetic field, and it still protects us from space radiation and solar storms.
Above: Supercomputer models of Earth’s magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is the sort of complicated magnetic field Earth has during the upheaval of a reversal. [more]
===========================================================
They didn’t seem very worried about it at NASA then. They were more worried about solar cycle 24 producing a lot of solar flares at the time, which would disrupt a lot of our new technology.
When a big CME heads toward earth, it can cause havoc, whether our magnetic field is strong or not. For example, in 1859, long before our worries about Earth’s magnetic field started, there was the Carrington event:
At 11:18 AM on the cloudless morning of Thursday, September 1, 1859, 33-year-old Richard Carrington—widely acknowledged to be one of England’s foremost solar astronomers—was in his well-appointed private observatory. Just as usual on every sunny day, his telescope was projecting an 11-inch-wide image of the sun on a screen, and Carrington skillfully drew the sunspots he saw.
Right: Sunspots sketched by Richard Carrington on Sept. 1, 1859. Copyright: Royal Astronomical Society: more.
On that morning, he was capturing the likeness of an enormous group of sunspots. Suddenly, before his eyes, two brilliant beads of blinding white light appeared over the sunspots, intensified rapidly, and became kidney-shaped. Realizing that he was witnessing something unprecedented and “being somewhat flurried by the surprise,” Carrington later wrote, “I hastily ran to call someone to witness the exhibition with me. On returning within 60 seconds, I was mortified to find that it was already much changed and enfeebled.” He and his witness watched the white spots contract to mere pinpoints and disappear.
It was 11:23 AM. Only five minutes had passed.
Just before dawn the next day, skies all over planet Earth erupted in red, green, and purple auroras so brilliant that newspapers could be read as easily as in daylight. Indeed, stunning auroras pulsated even at near tropical latitudes over Cuba, the Bahamas, Jamaica, El Salvador, and Hawaii.
Even more disconcerting, telegraph systems worldwide went haywire. Spark discharges shocked telegraph operators and set the telegraph paper on fire. Even when telegraphers disconnected the batteries powering the lines, aurora-induced electric currents in the wires still allowed messages to be transmitted.
“What Carrington saw was a white-light solar flare—a magnetic explosion on the sun,” explains David Hathaway, solar physics team lead at NASA’s Marshall Space Flight Center in Huntsville, Alabama.
Notice, no mention in any of the historical reports of superstorm style bad weather, just unusual low latitude auroras and wacky telegraphs. Such an event will happen again in Earth’s history, we can be sure of it. From Wiki: “Ice cores contain thin nitrate-rich layers that can be used to reconstruct a history of past events before reliable observations. These show evidence that events of this magnitude — as measured by high-energy proton radiation, not geomagnetic effect — occur approximately once per 500 years, with events at least one-fifth as large occurring several times per century. Less severe storms have occurred in 1921 and 1960, when widespread radio disruption was reported”
Sure, it would be worse today if Earth’s magnetic field was weaker, but comparatively, the terrestrial magnetic field is a wimp and get’s pushed around by the sun anyway:
Now compare that story to what our buddy Caca Kaku has been saying:
But for now, the reality of solar cycle 24 is far less worrisome:
Adding to some of the media hype worry, the north magnetic pole is on the move. In fact, as Luboš Motl has recently pointed out, it has been accelerating in its movement. According to this 2009 NatGeo story, it is now on the move by about 40 miles per year towards Siberia:
There was the recent story about runways at Tampa International Airport having to be renumbered because the compass heading has changed. It also added to the worry and hype about the Earth’s magnetic field. Well, it is a story that is likely to be repeated in the years to come, as the pole drifts even more. At some point the FAA may just decide it isn’t worth trying to keep up with, and make runway numbers reflect GPS headings (based on true north) instead.
And that’s not the only effect. Soon, many USHCN and GHCN ASOS station in the USA will be out of alignment with magnetic north. Yes that’s right, they are aligned perpendicular to magnetic north, like this US Historical Climate Network climate monitoring station in Minneapolis, MN:
As far as I can tell, that’s about the only significant “climate disruption” we are going to see.
There’s of course the possibility that a weaker magnetic field might provide for some increased thunderstorm development, such as this linkage between Forbush decreases and thunderstorm electricity, but there doesn’t appear to be any strong linkage to synoptic scale storm formation that we know of. The issue of the sun modulating cosmic ray passage to Earth which is a different issue altogether.
Now compare what has been presented above to the article in Helium that everyone is concerned about:
(Magnetic polar shifts cause massive global super storms)
On the heels of the lashing the British Isles sustained, monster storms began to pummel North America. The latest superstorm—as of this writing—is a monster over the U.S. that stretched across 2,000 miles affecting more than 150 million people.
Yet even as that storm wreaked havoc across the Western, Southern, Midwestern and Northeastern states, another superstorm broke out in the Pacific and closed in on Australia.
The southern continent had already dealt with the disaster of historic superstorm flooding from rains that dropped as much as several feet in a matter of hours. Tens of thousands of homes were damaged or destroyed. After the deluge bull sharks were spotted swimming between houses in what was once the quiet town of Goodna.
Shocked authorities now numbly concede that some of the water may never dissipate and have wearily resigned themselves to the possibility that region will now contain a small inland sea.
But then only a handful of weeks later another superstorm—the mega-monster cyclone Yasi—struck northeastern Australia. The damage it left in its wake is being called by rescue workers a war zone.
Do you recognize the writing style? Let’s look at a similar example.
We have recently been told that these storms were caused by “man-made global warming”, let’s listen to Al Gore:
As it turns out, the scientific community has been addressing this particular question for some time now and they say that increased heavy snowfalls are completely consistent with what they have been predicting as a consequence of man-made global warming:
“In fact, scientists have been warning for at least two decades that global warming could make snowstorms more severe. Snow has two simple ingredients: cold and moisture. Warmer air collects moisture like a sponge until it hits a patch of cold air. When temperatures dip below freezing, a lot of moisture creates a lot of snow.”
“A rise in global temperature can create all sorts of havoc, ranging from hotter dry spells to colder winters, along with increasingly violent storms, flooding, forest fires and loss of endangered species.”
There’s a catastrophe prediction on every street corner it seems:
Me, I’m not worried about the magnetic field flipping any more than I am about the sun turning into a red giant. It’s out of my hands. The best you can do is to adopt the old Boy Scout motto: Be prepared.
For what, I’m not sure, so I don’t worry too much. Nature so far has allowed life to go along on this planet, mostly unabated for millions of years. Sure, we could get squished like a bug tomorrow by an asteroid, but can we do anything about that if we know today?
Bobby McFerrin had it right:
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We have loads of satellites now studying interactions between earth’s magnetosphere and field with the solar magnetic field. We can now see how those interactions are occurring enhancing our understanding of the magnetic reconnection process. But we don’t see or I don’t, the loads of satellites at 6 to 16 solar radii, studying solar magnetic field and plasma interactions which is a part of the suns magnetic reconnection region., that boundary region. Where is the exact location of the the tip of the solar gravitational focusing cone today and how does it stroke up and down and in and out at 16 to 20 solar radii? We might be able to see the higher order spherical harmonics working on the solar surface now.
Atmospheres of Venus and Mercury show us some of the gas break down as you get nearer the solar disk region. Howzit that venus gets to rotate in it’s gaseous layer of ionization clockwise? The interplanetary region is by layers.
Yasi was caused by which magnetic pole drifting ? /sarc
Michele – Sorry, hadn’t checked that one, missed out etc, should be:
http://www.scientificpsychic.com/etc/timeline/timeline.html
This isn’t making it any clearer…
http://www.bibliotecapleyades.net/tierra_hueca/inner_earth/inner1.htm
“The outer core is said to consist mainly of liquid iron, and the inner core of solid iron.”
“P waves can travel through solids, liquids, and gases, while S waves can only travel through solids”
– it then says:
“The S-wave shadow zone is larger than the P-wave shadow zones; direct S waves are not recorded in the entire region more than 103° away from the epicentre. It therefore seems that S waves do not travel through the core at all, and this is interpreted to mean that it is a liquid, or at least acts like a liquid. The way P waves are refracted in the core is believed to indicate that there is a solid inner core. Although most of the earth’s iron is supposed to be concentrated in the core, it is interesting to note that in the outer zones of the earth, iron levels decrease with depth.”
With graphics.
So, is it solid or liquid at the centre?
Wouldn’t the heavier elements spinning in a ball of liquid be pushed to the outer edges?
If there’s great pressure and heavier elements spin out, what could be left at the centre? A gas? Which the S-wave is avoiding because picking up as not a solid?
In which case is there something else defracting P-waves, since those going through directly could be through solid, liquid or gas?
Leif Svalgaard @ur momisugly February 9, 2011 at 8:25 pm
says:
As you can see on pages 63 [for H] and 65 [for I] of Vuk’s link: http://www.ngdc.noaa.gov/geomag/WMM/data/WMM2010/WMM2010_Report.pdf
The asterisk marks the geomagnetic pole.
I was refering to the Dip pole location. That report gives the location as 84.97N 132.35W on page 18, which is close to cordinates given to me by nrcan, as measured in 2007. TheWMM report only estimates the position of the Dip pole because it is not measured every year.
There is a made for tv that shows Larry Newitt and Jean-Jacques Orgeval going out to measure the dip pole at:
When North Goes South
http://www.cbc.ca/documentaries/natureofthings/2010/northgoessouth/
Myrrh,
Re: February 10, 2011 at 7:00 am
“Scientific Psychic” doesn’t inspire much confidence. 😉
Re: February 10, 2011 at 4:50 am
When we look at stuff swirling up here on the surface, like in a centrifuge or bowl, centrifugal force separates what’s in the mix by mass, the more massive (heavier) bits move furthest away leaving the less massive (lighter) bits nearer the center. Note: Also review centripetal force. Here’s the quickie understanding of the difference. When spinning a weight on a piece of string, the string exerts centripetal force which keeps the weight from flying away. The weight feels centrifugal force, which makes it want to fly away straight out from the center of rotation. With stuff swirling in a bowl, the bowl is supplying the centripetal force that keeps the stuff from swirling out of the bowl (along with the force of gravity confining the stuff to the bowl, if applicable).
Under the Earth’s crust, the force of gravity is relatively strong. More massive stuff, being heavier, tends to go to the center. Something moving towards the center would feel the force decrease as the mass “above” would increase while that “below” would decrease. There is also centrifugal force trying to move the more massive stuff outwards, against what gravity is trying to do. The centrifugal force also decreases, as the speed decreases as you approach the center of rotation.
As things have turned out, there’s a solid inner core of basically iron and nickel (kept solid by the enormous pressure), the mostly iron liquid outer core with the heavier elements in it settling around the inner core, and the gooey mantle which has lighter elements, primarily oxygen, silicon and magnesium. Gravitational separation was dominant as the young Earth formed, and still is. As to what you quoted:
That would be expected in the mantle. There is bottom to top convective churning. The lowest part of the mantle melts, gravity pulls the heavier iron (and other heavier elements) towards the center, what’s left is churned upwards, where it mixes with mantle material having more iron. Thus the concentration of iron decreases going through the mantle towards the core as the iron is being separated out into the liquid outer core.
Further reading:
http://wattsupwiththat.com/2010/12/17/first-measurement-of-magnetic-field-in-earths-core/
http://wattsupwiththat.com/2011/01/08/moon-revealed-to-have-an-earth-like-core/
Structure of the Earth discussed. There is also a Wikipedia entry which leads to more in-depth info:
http://en.wikipedia.org/wiki/Structure_of_the_Earth
kadaka (KD Knoebel) says:
February 10, 2011 at 11:43 am
“Scientific Psychic” doesn’t inspire much confidence. 😉
Shrug. It’s where I found the reference, so I posted it, and, pretty much standard as time-lines go. Looking because I was interested in the question, it was the first thing I found unusual in descriptions of the cretaceous re magnetic reversal; narrowing it down to this gives studies on the subject.
Re: Myrrh’s “Wouldn’t elements spinning in a ball of liquid be pushed to the outer edges?”
Thank you for your explanations, and I’ll take a look at your links, but I am as yet not convinced.
Meanwhile, at what point does Earth’s gravity take over from the centrifugal force spinning heavier elements away from the centre?
And, do you have any thoughts on the extract from the article I posted, my question on the conundrum posed by the S & T waves (expanded in my later post, 7:25 am.)?
– The S waves show no solid in the centre, the T waves show there is defraction and the assumption is that this is because the core is solid, which the S waves contradict.
I’m more worried about the 2021 thing. Ten years from now, if you can say you are alive and financially solvent, you will be considered a “one percenter.”
From Myrrh on February 10, 2011 at 1:06 pm:
I’m currently engaged in cooling/warming research, about to hit a tipping point leading to a fast total ice loss. Thus as I’m busy defrosting the freezer, this reply will be short.
A: Escape velocity. That’s what it amounts to. Review circular motion. Normally we simply say that the centripetal force is equal to the centrifugal force, since that weight on the string is sticking to the circle thus the forces acting on the weight sum up to zero. Force = mass times acceleration. On the surface, we say the force of gravity is mass times a standard gravity (g), 9.8 meters divided by seconds squared, force in units of Newtons. From the laws of circular motion, we get the magnitude of centripetal acceleration is velocity squared divided by radius. That’s the Earth’s radius. When the force of gravity is equal to the centripetal force, that’s where the change is. So m*g = m*(v^2)/R, the m cancels out, punch in the numbers and solve for v, the escape velocity.
Unfortunately, we’re moving towards the center of the Earth. Newton’s Law of Universal Gravitation gets invoked. To find the force of gravity, you have to figure out the force exerted from that portion of the Earth’s mass “below” and subtract the force from the mass “above.” Ugly math, computers…
Let’s just say it doesn’t look like centrifugal force will matter as far as the interior of the Earth is concerned.
Yeah, it’s incomplete. Read this about seismic waves, and about S-waves as well. Then you can better digest this piece which explains how they figured out there must be a solid inner core.
kadaka – again thank you for your time and explanations. I’m still not convinced that’s the whole picture, or adequate explanation for the peculiar patterns of the P and S waves which appears to me to begin with an assumption of a solid ball of iron and that is not yet proved.
http://news.science.mag.org/sciencenow/2010/08/earths-moving-melting-core.html
http://in.answers.yahoo.com/question/index?qid=20070926051507AABRA8X
One last piece, http://www.ouramazingplanet.com/earth-inner-core-shifts-eastward-0409/
From Myrrh on February 11, 2011 at 2:35 am:
????
From the last link I provided, it can be noticed that first they thought the core was all liquid, then it was deduced there was a solid inner core.
Your first link, as posted, has an extra dot in it. Correct version:
http://news.sciencemag.org/sciencenow/2010/08/earths-moving-melting-core.html
Here’s a more descriptive piece about it:
http://www.csmonitor.com/Science/2010/0804/Is-the-earth-s-core-moving-eastward
It’s not that hard to follow. On one face of the inner core, which is very hot and barely kept solid by the pressure, there’s just a little bit less pressure so there’s some melting. The dense liquid moves around the inner core and solidifies on the other side, where there’s a little bit more pressure. Mark the center of the inner core at one point of time, at a later time the mark will be shifted towards the melting face. It’s an incredibly slow process, and the melting is only taking place on the surface, the inner core is still solid.
In a way, it’s like your bones. They’re in a constant state of renewal, calcium is removed and deposited continually. Your entire skeleton is recycled about every seven years. Does that mean your bones aren’t solid?
http://in.answers.yahoo.com/question/index?qid=20070926051507AABRA8X
That’s the best answer they have? Which doesn’t even match the question? Which was bulk copied from elsewhere, without citing the source, right down to the captions of the missing graphics?
Here’s the original, with the graphics:
http://www.psc.edu/science/Cohen_Stix/cohen_stix.html
This sounds more dramatic than it is, leading one to imagine crystals like salt or quartz, which is not the case. When metals solidify, the atoms arrange themselves into a matrix which achieves stability by “sharing” electrons without forming chemical bonds. This is what makes them great conductors of electricity, the electrons can move freely through the matrix, and makes them flexible as a solid, able to deform when stressed rather than shatter. Under immense pressure, with an incredibly slow process of solidification, the conditions are ideal for the solidifying atoms to carefully align with an existing matrix, rather than hurriedly clump into new matrices. Thus it it possible the entire round solid core could be a single matrix, with a single matrix being called a crystal.
Myrrh said on February 11, 2011 at 10:10 am:
Ah, that’s the originating piece for the one article I found! Didn’t see that before I posted. ☺
kadaka says:
February 11, 2011 t 11:08 am
????
From the last link http://tigger.uic.edu/~rdemar/geol107/dect16.htm I provided, it can be noticed that first they thought the core was all liquid, then it was deduced there was a solid inner core.
No, it was deduced that there was something solid there. My question, I was echoing the earlier one, was about the assumption that this is a solid ball of iron surrounded by liquid iron, etc. as you described it above in great detail.
My point is still, that I haven’t found an explanation for it. A description of it as you’ve given is circular reasoning, regardless that it was excellently articulated.
Your first link, as posted, has an extra dot in it. Correct version: http://news.sciencemag.org/sciencenow/2010/08/earths-moving-melting-core.html
Here’s a more descriptive piece about it:
http://www.csmonitor.com/Science/2010/0804/Is-the-earth-s-core-moving-eastward
Thank you, I don’t have a copy and paste function at the moment and although I do check usually, and I remember checking these.., bleary eyes win out sometimes.
It’s not that hard to follow. etc.
Yes, but. The reason I posted it is that it didn’t gel with your earlier explanation. Which you have now re-worked in the “etc.” and return to me changed with added condescending tone..
I have no particular point of view about the earth’s interior, happily in company with those I’ve read who still treat the theory as a working hypothesis, with the inherent freedom that gives to speculate as new information bubbles up to us on the surface. I do have questions because I’m interested in it.
The article I posted begins:
Strange forces are at work 5000 kilometers below Earth’s surface. The inner core is acting in ways that scientists can’t explain. Theoretically, the core should be drawing iron from its molten surroundings and crystallizing it into solid metal. But that alone doesn’t account for a number of odd observations – unless, as a few scientists speculate, the core is also melting.
It is not, therefore, a cut and dried ‘scientific fact’ that the inner core is solid and made and kept so by the intense pressure, which is the ‘classic’ theory as you described it above.
If there’s one thing I’ve learned from exploring AGW arguments, is not to take ‘assumptions’ as ‘scientific fact’.
There was one question I thought of asking you earlier and I did spend some hours searching for it before I found this article. I wondered how it was established that the inner core was solid because under pressure.
You gave a temperature at the inner core 5505°C (5778 K), (in your reply to Rational Debate February 9 11:23 pm) and in my reply to Leif (February 10, 4:18 pm) I’d found an 1987 article which gave the temp as 6900 K, which said previous estimates were between 3000 and 4000 K.
Leif said in his reply to me: “The melting point also depends on the pressure, so at the higher pressure deeper down you need a still higher temperature for the material to melt.”
You said in reply to Rational Debate: “The pressure is so high at the inner core, iron is solid at a temperature where it’d be vapor at the surface.”
So the question I was framing in my mind was – at what temperature does it have to be to tip the balance and begin melting solid iron at the pressure in the centre of the Earth?
I also wanted to know how they ‘established’ the temperature at the centre, obvious from the different measurements that there is some room for manoeveur here, and I thought the higher 6900 K was estimated by first assuming that the inner core was solid because under pressure, as the theory.
So, is there another way of estimating the temperature at the centre?
Re your comments on the yahoo link, and further.
They gave the names of the Scientists involved and they said where it was published…
This sounds more dramatic than it is, leading one to imagine crystals like salt or quartz, which is not the case. etc.
Hmm, again missing the point. The drama is in the concept – that the Earth’s solid-iron inner core is “anisotropic” –it has a directional quality, a texture similar to the grain in wood, that allows sound waves to go faster when they travel in a certain direction., which has recently been confirmed, and in the question, What, exactly, is the nature of this inner-core texture?, adding, To this question, the seismic data responds with sphinx-like silence. “The problem,” says Ronalk Cohen of the Carnegie Institution of Washington, “then we’re stymied. We know there’s some kind of structure, the data tells us that, but we don’t know what it is. If we knew the sound velocities in iron at the pressure and temperature of the inner core, we could get somewhere.” To remedy this lack of information, Stixrude and Cohen turned to the CRAY C90 at Pittsburgh Supercomputing Center. …….. Prevalent opinion before these calculations held that iron’s crystal structure in the inner core was bcc. To the contrary, the claculations showed, bcc iron is unstable at high pressure and not likely to exist in the inner core. ……. Unheard of until this work, the idea has prompted realization that the temperature-pressure extremes of the inner core offer ideal conditions for crystal growth. And then the other reason I posted it, A strongly oriented inner core could also explain anomalies of Earth’s magnetic field, etc.
I thought it interesting in context of my question re what was the core really like?, if it had one.., and in this discussion in context of how this could affect the Earth’s magnetic field.
I then looked for information on seismic waves through such crystal structures, without finding anything so far. But I did find a really interesting piece of applied science history re iron, which had all kind of tidbits, like “iron decreases in strength from long exposure to the intense heat necessary in making a gun of this size, without a possibility of restoring the fibre by hammering with the hammer at present in use in this country.” Part one explains crystallization, part 2 the causes.
http://chestofbooks.com/crafts/metal/Metal-Worker-Assistant/Crystallization-Part-3.html
Which brings me to the other question I had rattling around re descriptions of ‘solid iron core because of pressure’, what does it mean when this is described as “freezing”?
Does it actually get cold? You said the heat isn’t lost when a solid is formed under pressure, so I don’t understand this.
If, there is actually heat loss at some point I wonder if we end up with deformities such as described in section 2? Perhaps an empty space in the centre of the Earth as the “hollowness is found in the centre of almost every large forging, greater in proportion as the forging is larger.” Not easily overcome.
Re my “and further”:
Hmm, and again, “The idea counters traditional theory that the big ball at the center of the Earth stands still, growing uniformly in all directions as the planet cools. It could shed light on the nature of the core – such as its age, appararent seismic mismatches, and a mysterious coating of dense fluid on its surface.”
So, no, it’s not at all hard to follow, but it isn’t the traditional theory.
So what is the core made of? http://geology.about.com/od/core/a/about_the_core.htm with links to core people and ideas.
Didn’t have time to check the last link properly before, it’s not current, and irritatingly the past info on it is subject to some kind of reload loop so difficult to read.
http://www.sedigroup.org is current, and dedicated to the Study of the Earth’s Deep Interior and its intent ” is to amalgamate all sources of data and all points of view to generate the most coherent and consistent picture of the workings of the Earth’s deep interior” and membership informal, and sufficient to send email expressing interest in joining.
That is, the link on the page to “Core” takes to defunct web site.
Its taken about a week to get to something that still puzzles me:the nature of the earth’s core.
One point that I haven’t noticed in this thread:gravitational attraction at the ‘centre of earth’s mass’ would be the same in all directions.An oven proof being at this centre would experience weightlessness.A homogeneous substance would be acted on by (weak?) centrifugal force.Like the eye of a hurricane ,I cant help imagining at the earth’s core some kind of rarefaction.The S and P wave stuff only indicates a boundary change,it’s clear from the various opinions that no one really knows what happens down there.