[Ophiolite]

keep_talking, on 9 January 2012 - 11:29 AM, said:

A planet cannot have a molten outer core without the surface having constantly changing plate tectonics.

I am not sure where you got this idea, but you are mistaken. Keep in mind that on the Earth the outer molten core is separated from the crustal plates by a couple of thousand kilometres. I'm not sure what mechanism you were thinking of to provide the causal connection? Mantle plumes perhaps?

keep_talking, on 9 January 2012 - 11:29 AM, said:

Earth is one of the FEW planets we know of that has a constantly changing tectonic plate.

Well, it is the only planet we know of that seems to have currently active plate tectonics. There is some evidence for it in the early stages of Martian history; Venus underwent a resurfacing event some 600 my bp; Mercury seems to be inactive in that regard.

keep_talking, on 9 January 2012 - 11:29 AM, said:

Can we say the rapid cooling of the surface of Mars had nothing at all to do with its distance from the sun? I want to say there are a multitude of factors in Mars' wasteland like surface.

This is certainly true and the discussion so far has focused on only one aspect.

[keep_talking]

Ophiolite, on 9 January 2012 - 12:12 PM, said:

I am not sure where you got this idea, but you are mistaken. Keep in mind that on the Earth the outer molten core is separated from the crustal plates by a couple of thousand kilometres. I'm not sure what mechanism you were thinking of to provide the causal connection? Mantle plumes perhaps?

The tectonic plates move due to convection cells below the surface of the earth. These convection cells are caused due to the intense heat at the core of the Earth, and rest directly on the outer layer of the core of our planet all the way to the bottom of the crust. The molten outer layer circulates the convection cells below the surface allowing the mantle to be pushed across the surface. Without a molten outer core, there would be no plate tectonics on Earth.

This is of course, a general hypothesis but can be tested off Earth. We know Jupiter has a molten outer core of liquid hydrogen because of its staggering array of magnetic storms at the poles from its magnetosphere. The Hubble Space Telescope verified this. The problem is we cannot see the surface of Jupiter. The facts point in the direction of a sea of liquid hydrogen because the intense pressure below the atmosphere of the planet. Temperatures can easily reach 10,000 C at the "surface" of the hydrogen ocean and allow it to freely flow on the surface. This gives almost the same conditions as the outer core of Earth.

This post has been edited by keep_talking: 9 January 2012 - 01:09 PM

[swansont]

keep_talking, on 9 January 2012 - 11:29 AM, said:

Can we say the rapid cooling of the surface of Mars had nothing at all to do with its distance from the sun? I want to say there are a multitude of factors in Mars' wasteland like surface.

No, I don't think we can say that, because the rate of net energy loss depends on the rate at which energy is absorbed, and radiation falls off with the square of the distance. Mars gets just over half of the energy per unit area that the earth gets (orbit at 1.38 AU, 1/1.38^2 = 1/1.9 = ~53%)

[TimeContinuum]

I'd wager the inner core is more like 2 cores. The outer-inner being a plasma-core. Then the inner-inner being a fusion core. Then once we have enough energy of our own, we can start a diamagnetic effect with the sun and slowly float away from it =)

This is all just a guess by me.

[Ophiolite]

TimeContinuum, on 19 January 2012 - 05:09 AM, said:

I'd wager the inner core is more like 2 cores.

Please contact me by pm with your bank details so I can lift my winning bet.

[TimeContinuum]

Ophiolite, on 19 January 2012 - 06:35 AM, said:

Please contact me by pm with your bank details so I can lift my winning bet.

What is your proposed test to verify? Do you have a craft that will allow us to journey to the center of the Earth?

This post has been edited by TimeContinuum: 20 January 2012 - 07:14 PM

[Ophiolite]

TimeContinuum, on 20 January 2012 - 07:13 PM, said:

What is your proposed test to verify? Do you have a craft that will allow us to journey to the center of the Earth?

Several. One of them is called seismology.