Computer model shows moon's core surrounded by liquid and it's caused by Earth's gravity

Jul 28, 2014 by Bob Yirka report
Moon
The image of the moon is courtesy of NASA.

(Phys.org) —A team of researchers with team members from China, the U.S. and Japan has created a computer model that shows that the moon is not solid all the way through—instead, it shows a liquid layer surrounding the core. In their paper published in the journal Nature Geoscience, the team suggests the liquid layer, if it's really there, is caused by friction due to Earth's gravity.

Scientists have noted anomalies in measurements of the 's orbit and associated gravitational readings for some time. Such anomalies have defied explanation, however, as models built to replicate them have generally produced results that weren't very clear. At root however, has been the idea that the moon's core may be covered by a thin layer of liquid. The team noted that gravitational readings of the moon indicate that there is rotation at the core that is not the same as other rotation measurements near the core. This suggests a liquid outer layer.

To getter a better idea of what might be going on at the moon's center, the researchers built a computer model that takes into account the gravity exerted by the moon, the earth and the sun. When set into motion, the model showed that a liquid layer over the core gave the same gravity readings as scientists have found when measuring the real moon. This suggests, the team reports, that a liquid layer does truly exist, and likely has been there for a very long time.

As for why such a layer would exist, the team suggests that the tug of Earth's gravity—tidal heating—is likely playing a role, causing friction between the core and material above it, resulting in the creation and maintenance of a liquid layer.

A lot more research will have to be done, of course, before scientists accept the results of the . But if such research should prove that there is a liquid layer, scientists might have to do some rethinking of theories that describe the origin of the moon. If the moon was created due to a large body striking Earth, why did it not cool down over the four and half billion years since then, to the extent that it would be too cold for a liquid layer to exist today?

Explore further: Lunar rock samples reveal variations in water concentrations

More information: Nature Geoscience (2014) DOI: 10.1038/ngeo2211

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mikael_murstam
4.6 / 5 (5) Jul 28, 2014
Maybe it did cool down and then heated again due to friction?
Nik_2213
1.9 / 5 (7) Jul 28, 2014
Have they factored in the varying rates of tidal dissipation due to continental drift, flood basalts, ice ages, orbital variations etc etc ?? It will not have been 'linear' with time...
hemitite
5 / 5 (9) Jul 28, 2014
To begin with, the moon has experienced massive tidal heating early in its history as it was thought to have formed just outside the Roch limit and migrated outward since then, So the tidal heating of the moon in its early days should have been rather significant. And as Mikeal said above, the subsequent tidal friction could have maintained some fraction of this initial melt up to the present day.
AZstrider
1.7 / 5 (6) Jul 28, 2014
Doesn't this mean the Moon is loosing energy? I know the Moon is currently moving away from the Earth. Does this energy loss imply the trend will reverse and it will eventually come 'home'?
Whydening Gyre
2 / 5 (7) Jul 28, 2014
Sorry, but it's a MODEL. I'd rather wait for some "shovels in the dirt" type info. Far too many models are being treated as realities and then when new info comes in - oops! That was unexpected...
Valentiinro
5 / 5 (9) Jul 28, 2014
Sorry, but it's a MODEL. I'd rather wait for some "shovels in the dirt" type info. Far too many models are being treated as realities and then when new info comes in - oops! That was unexpected...


If you want to fund someone to drill a hole through the moon, go ahead buddy.
Meanwhile, attempting to find a mathematical explanation using the current data is the most cost effective solution.
Steve 200mph Cruiz
5 / 5 (11) Jul 28, 2014
Sorry, but it's a MODEL. I'd rather wait for some "shovels in the dirt" type info. Far too many models are being treated as realities and then when new info comes in - oops! That was unexpected...


Jesus christ.. we have seismographs on the moon and incredibly detailed maps of the moons gravitational field. They come up with a perfectly plausible explanation, and you just down it because "it's just a model, hurr".
You're not contributing anything at all, if you got a problem with it, go look at the data and come up with your own freaking theory, and ironically, the only way you'd even be able to show it is with a model of your own.
We freaking discovered Neptune with a mathematical model, we discovered carbon nanotubes with a mathematical model, math is important, maybe you should learn it.
Whydening Gyre
1 / 5 (2) Jul 28, 2014
Jesus christ.. we have seismographs on the moon and incredibly detailed maps of the moons gravitational field. They come up with a perfectly plausible explanation, and you just down it because "it's just a model, hurr".
You're not contributing anything at all, if you got a problem with it, go look at the data and come up with your own freaking theory, and ironically, the only way you'd even be able to show it is with a model of your own.
We freaking discovered Neptune with a mathematical model, we discovered carbon nanotubes with a mathematical model, math is important, maybe you should learn it.

I seem to have struck a nerve...:-)
I was simply trying to make a subtle point as to the acceptance of a model as the definitive answer to a question, when physical research has not been done (for whatever the reason).
Science is ABOUT the hands on stuff... Otherwise, you're just vicarious speculators.
Steve 200mph Cruiz
4.9 / 5 (12) Jul 28, 2014
Whydening
Dude, we're never going to drill a hole to the liquid outer core of the moon, at least for any foreseeable reason in 2014. Sorry, I may have jumped the gun on you personally, but the internet is about as impersonal as it gets, and no matter where you go, everyone is whining about "the model", either out of politics or conspiracy, so being that guy throws you in that position.
Nothing is vicarious about it all, natural sciences can be a complete bummer, it's a work of love, not ego, especially ecologists, climatologists, biologists, and paleontologists.
It was Oscar Wilde who said, If you're going to tell the truth, make them laugh, otherwise they'll kill you.And unfortunately, scientific journals aren't funny.
The frontiers of science have evolved beyond "hey I can touch this", about a century ago. Theory is all we have into the future because of our limitations as biological beings, as technology advances because of theory, natural theories are tested, but that's all we got.
Uncle Ira
4.5 / 5 (11) Jul 28, 2014
Sorry, but it's a MODEL. I'd rather wait for some "shovels in the dirt" type info. Far too many models are being treated as realities and then when new info comes in - oops! That was unexpected...


@ Whydening-Skippy. You know I am not the scientist so this might be wrong. I'm reading a really good book by John-Gribbin-Skippy who is a real scientist at Cambridge astrophysicist school in England. It's called The Scientists-Skippys (I just add the Skippys for fun) and it's about all the scientists from Copernicus-Skippy to modern day scientists, and it's a good book too for peoples like me because I can understand most of it.

Anyway, what I wanted to say about it is he, Gribbin-Skippy says all the physicists have is models. Everything they have is models. That is the business of science is making the models that describe what the universe is really like.He says that some models are better than others, and some are a waste of time.But everything they do is models of reality.
Uncle Ira
4 / 5 (8) Jul 28, 2014
@ P.S. for you Whydening-Skippy. I was running out of letters so I wanted to add, that if might be that I'm reading what he says wrong so don't hold me to that. If it's wrong that is my fault, not the Gribbin-Skippy's fault because he the professor at the astrophysicist school. But it's a really good book if you like that sort of thing, about how the scientist-Skippys go about deciding on what to put in their theories and what to not put in because it's foolishment.

It's called The Scientists by John Gribbin (no Skippys) and cost about $14 or $13 from the Amazon. I first picked him up at library and liked it so much I bought him to keep.
Whydening Gyre
4.4 / 5 (7) Jul 29, 2014
No Prob, Quick-Steve...:-)
Was kinda tryin to do an Oscar Wilde, but, man - you guys can be a tuff crowd on occasion...:-)
Thanks, Ira. Will look it up.
TCarey
1 / 5 (2) Jul 29, 2014
I must be missing something. It is my understanding for tidal friction heating to occur the moon has to be rotating in relation to the earth.
Egleton
2.7 / 5 (3) Jul 29, 2014
I'm with WG.
An Empiricist.
If the model doesen't fit the evidence, the evidence triumphs- the model must go.
There is a lot of lip service paid to this idea these days.
A well run experiment is NOT required to afirm the prevading paradigm.

There are too many lumps under the carpet; objects that are acknowledged to be true but are ignored because there is no money bucking the powerful old Profs.
antialias_physorg
4.9 / 5 (11) Jul 29, 2014
I must be missing something. It is my understanding for tidal friction heating to occur the moon has to be rotating in relation to the earth.

Having an elliptical orbit is enough to experience a gravitational differential (and with it some heating).

As for models: You have to have a model first before you do an experiment to validate it. They currently have a model with a simple mechanism that fits observable data - which is no mean feat. (Note: It's much easier to come up with overly complicated models - epicycles if you will - than with simple ones)

And now the final trick will be devising a new experiment to test it (e.g. putting more sensitive seismometers on the Moon, and having another impactor mission)
Torbjorn_Larsson_OM
4.9 / 5 (7) Jul 29, 2014
Interesting. But the problem of Yirka (or if it is the original article) doesn't make sense.

From the abstract: "We also find that tidal dissipation is not evenly distributed in the lunar interior, but localized within the low-viscosity layer, which implies that this layer may act as a thermal blanket16 on the lunar core and influence the Moon's thermal evolution." So the heating should be enough for steady state, or the thin layer wouldn't stay liquid for long. And conversely, the liquid layer would affect the Moon cooling.

There is little here that implies such a find would stress the main theory on Moon formation.
Torbjorn_Larsson_OM
5 / 5 (7) Jul 29, 2014
"models that describe what the universe is really like."

Exactly, models map to reality. And the existence of reality is tested by observation (in quantum mechanics, in the form observation-observables; classically that maps to action-reaction). The upshot is that we now know the process converges, e.g. we now know the laws for everyday physics for certain, and we also know that quantum mechanics is WYSIWYG (what you see is what you get). That is because there is a finite number of laws (properties of reality), or Hilbert spaces of quantum field theory wouldn't work.

To sum up, our best maps are now essentially 1:1 to reality. It would be an extraordinary claim to say that models can't be "realities", and the evidence seems to go in the other direction.

That doesn't mean that new models, like observations, can't be absolute crap at times.
Egleton
5 / 5 (3) Jul 29, 2014

"To sum up, our best maps are now essentially 1:1 to reality."

So which is it? String theory, Multiverse, Holographic Universe, Digital simulation or some other that I am unaware of?
The two-slit experiment is still a head scratcher.

Or is it Hubris?
Whydening Gyre
3.4 / 5 (5) Jul 29, 2014
A note to all, re my original comment on models;
I'm not disagreeing with the use of the models. I understand ideas must be developed and subsequent action strategized. However, I find it frustrating that we keep building more and more models that (currently) have little or no chance of seeing light of day.
I guess I am subtly(?) lamenting our inability to perform the followup "boots in the dirt" work, with their subsequent surprises...
When did I become an old guy?!?!
antialias_physorg
4.8 / 5 (9) Jul 29, 2014
To sum up, our best maps are now essentially 1:1 to reality.

Far from it. The map is not the territory.

Models are there as a type of packing algorithm: So that we don't have to evaluate each and every event separately (it's a bit of an extension of how our brain works: by classifying stuff that looks the same into a group)

However therein lies the problem: Nothing in the universe is the same. We can say X is replaceable with Y (e.g. one hydrogen atom with another) within some given, accepted uncertainty - but not beyond that.

So while our models are very accurate (and therefore: useful) there is only one model that can give you exact results: and that model is as big as the universe.

Otherwise we'd be at the point where our theories are 'truth'. And that isn't part of science (i.e.: unattainable...and provably not a characteristic of the universe in any case)
Whydening Gyre
3.4 / 5 (5) Jul 29, 2014
Brilliant summation, AA..
Icemoon
1 / 5 (3) Jul 29, 2014
https://www.faceb...26444842 seems to have a effective explanation...
Urgelt
5 / 5 (3) Aug 04, 2014
If tidal forces are injecting heat energy directly into the core-mantle boundary sufficient to keep that boundary liquid, then wouldn't we see at least a trace of a geomagnetic field from core movement decoupled from the mantle?

Bleh. This being the Physorg.com comments section, I suppose I have to explicitly say here that I'm asking a sincere question of science, rather than propounding on some nutso theory of my own that exists only in my arguably incognitive organic head.
eric96
5 / 5 (4) Aug 04, 2014
"If the moon was created due to a large body striking Earth, why did it not cool down over the four and half billion years since then, to the extent that it would be too cold for a liquid layer to exist today?"

Awful reasoning. First of all, the moon is made out of matter which means somehow it arose from colliding matter which should have necessarily cooled down given the distance to the sun. However, the moon's mantle is an isolating layer, and given the half the moon is fairly hot while exposed to the sun, its very possible that earth's gravity could provide sufficient tidal forces for a perpetual liquid layer close to the core. Perpetual because the sun's energy is constant and will grow while the earth's gravity is constant. The most exiting thing about this being true is that if it is true, first satellites near jupiter and saturn would all likely have a liquid layer near their core, and under the right conditions may harbour life (Titan and Europa).
SHREEKANT
1 / 5 (2) Aug 20, 2014
"But if such research should prove that there is a liquid layer, scientists might have to do some rethinking of theories that describe the origin of the moon."

MY VIEW: Moon is not born by collision theory. Actually moon formed just after, better to say simultaneously with the formation of earth. I have been writing it since long.

Please refer my comment dated  17th, Jan'2014 at 5.22PM in
http://www.univer...he-moon/

Please refer my comment dated  03rd , Apr'2014 at 11.08 AM in
http://www.space....ery.html