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Discovery of the Earth’s Inner, Inner Core

10 Mar , 2008 by

The traditional view of the Earth’s interior has the crust (where we live), the upper and inner mantle, the outer core, and the inner core; wrapped around each other like layers of an onion. But now textbooks will need to be revised. It turns out there’s an inner, inner core.

The core of Earth is known to have an inner core of solid iron about 2,400 km (1,500 miles). Wrapped around that is a fluid outer core that reaches 7,000 km across (4,300 miles). As the solid core rotates inside the fluid core, it generates the magnetic field that helps us navigate, and protects the planet from harmful radiation and the effects of the solar wind.

Geologists from the University of Illinois at Urbana-Chamaign have been probing the interior of the planet, trying to get a better sense of its structure. And that’s harder than it sounds. You can’t just look down through thousands of km of solid rock.

There were using the natural waves that pass through the Earth after earthquakes shake on the surface. The waves are bent and reflected as they pass through the various layers inside the planet.

The team was specifically studying how the waves were affected as they passed through the solid inner core and were surprised to see that it wasn’t a uniform sphere of iron.

Instead, the seismic waves clearly showed that there’s an additional layer at a diameter of 1,180 km (733 miles), which makes this less than half the diameter of the inner core.

This is the Earth’s inner, inner core.

So what is it? Here’s what the lead scientists, Xiaodong Song had to say:


“Our results suggest the outer inner core is composed of iron crystals of a single phase with different degrees of preferred alignment along Earth’s spin axis,” Sun said. “The inner inner core may be composed of a different phase of crystalline iron or have a different pattern of alignment.”

It’s still iron, just not in the same crystalline structure. Perhaps its time to give the layers new names, inner inner core doesn’t quite work for me.

Original Source: University of Illinois News Release


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Andrew
Member
Andrew
March 10, 2008 11:19 AM

If there’s a different layer of iron, shouldn’t that be detectable in the Earth’s magnetic field?

Andy C
Guest
Andy C
March 10, 2008 12:19 PM

> If there’s a different layer of iron, shouldn’t that be detectable in the Earth’s magnetic field?

Andrew, although I’m far from being an expert on the subject, I think the answer to your question is ‘no’, because it is not the crystalline phase that determines iron’s magnetism, but the electronic spin of the atoms (they’re all aligned in magnetised iron).

Improbus
Guest
Improbus
March 10, 2008 3:17 PM

Maybe they should call it “the Pit”. Like a peach pit.

PMF71
Member
PMF71
March 10, 2008 5:14 PM

How about “inner core mantle” and “inner core centre”

Phil Glover
Guest
Phil Glover
March 11, 2008 8:24 AM

Phil says;
How about ” core blimey ”
Iron core- inner or outer, Why is anything heavy at the centre, what’s the big attraction ?

GrahamC
Member
GrahamC
March 11, 2008 2:42 AM

I’m not an expert on these things, but as the Earth’s core is well above the Curie temperature for iron, I think the magnetic field will be due to electric currents flowing through iron as a conductor rather than any feromagnetic properties.

Simon
Guest
Simon
March 11, 2008 4:59 AM

I reckon ‘sub inner core’ or ‘inner sub core’!

alphonso richardson
Guest
alphonso richardson
March 11, 2008 5:08 AM

I like the sound of ‘inner core centre’. How about sub-core, outer & central?

SC
Guest
SC
March 11, 2008 6:25 AM

Hardcore / Softcore

=D

Ed
Guest
Ed
March 11, 2008 6:40 AM

How about “innermost core” and “inner core layer”?

drlove
Member
drlove
March 11, 2008 6:46 AM

How about the chewy nuget center!

Dan
Guest
Dan
March 11, 2008 7:22 AM

Perhaps “crystalline core”?

David Braun
Guest
David Braun
March 11, 2008 9:47 AM

I saw an article which suggested that the inner inner core consists of very heavy metals, including radioactive ones such as uranium which may contribute to the maintainence of the fluidity of the iron core.

me
Guest
me
March 11, 2008 10:05 AM

I’m for “innermost core”!

astrojr1
Guest
March 11, 2008 10:51 AM

How about inner core, middle core, outer core. The inner core is not inner any more so why hang on to it. Pluto’s not a planet, Janet, etc.

Jim (himself)
Guest
Jim (himself)
March 11, 2008 11:07 AM

Could it be possible that the rotational speeds of these two separate cores be the genesis of our magnetosphere.? Is the boundry between core 1 and core 2 constant in relative rotational speeds? How do they relate in axial repositioning ? Do they alter when the polarity shifts.? Is there a difference in the radioactivity between core 1 and core 2?

Bubba J.
Guest
Bubba J.
March 11, 2008 6:10 PM

Is it possible that we living on the surface a stellar remnant?

I mean look at the major chemical constituents of the planet.

Jim (himself)
Guest
Jim (himself)
March 11, 2008 11:41 AM

Is it possible to create the material of core 1 or core 2 in a labority setting? Do they share the same polarity ? Can we assume that the two core construct is the basis for all planitary developement in our system? How much difference is there in the density between core 1 and core2?

Josh M.
Guest
Josh M.
March 11, 2008 4:25 PM

I suggest we call it “Where Taco Bell gets their taco meat from”

Eugene Dusina, nuke physics
Guest
Eugene Dusina, nuke physics
March 12, 2008 2:24 PM
The inner core is “known to be iron”. How entertaining… Common sense says, IF the earth was EVER liquid, that at the center would be concentrated the heaviest elements. U238 with its few pct. of 235, and a few miles in diameter and at a pressure of about 10E16, would be expected to spontaneously fission, heat to tens of kilodegrees, sufficient to reduce density till fission became stable, and run for years. EARTH WOULD BE EXPECTED TO HAVE NATURAL NUCLEAR REACTOR AT ITS CENTER, as would all planets which went through a liquid phase in their creation. This would explain why the temp of the ground goes up ad infinitim as one drills deeper, would it not? Scientists… Read more »
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