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Posted on 10/21/2007 5:16:40 PM PDT by SunkenCiv
Extrasolar planets that are superficially similar to our own and sometimes termed 'super-sized Earths' may in fact have stagnant outer surfaces rendering them inhospitable to life. These rocky bodies are probably not much like Earth at all... Instead of possessing active plate tectonics, those that are five to ten times the size of Earth most likely have a geologically dead surface more akin to the hellish surface of Venus, they said... To make the find, O'Neill and colleague Adrian Lenardic of Rice University in Houston, Texas, modelled how gravity and stress forces would affect a planet if it were a scaled-up version of Earth. They found that a while the increased forces generated by convection currents in the mantle would act on a super-sized Earth, increased gravity would act to strengthen the rocky crust so the surface would no longer resemble the cracked eggshell-like configuration of Earth's tectonic plates. In other words, the surface of the planet would be too strong to allow the driving forces of magma to break the crust into large, active plates where rock is created or destroyed.
(Excerpt) Read more at cosmosmagazine.com ...
Geological consequences of super-sized EarthsAbstract: The discovery of terrestrial-scale extrasolar planets, and their calculated abundance in the galaxy, has prompted speculation on their surface conditions and thermal structure. Both are dependent on the tectonic regime of a planet, which is itself a function of the balance between driving forces, and the resistive strength of the lithosphere. Here we use mantle convection simulations to show that simply increasing planetary radius acts to decrease the ratio of driving to resisting stresses, and thus super-sized Earths are likely to be in an episodic or stagnant lid regime. This effect is robust when associated increases in gravity are included, as the more dominant effect is increased fault strength rather than greater buoyancy forces. The thermo-tectonic evolution of large terrestrial planets is more complex than often assumed, and this has implications for the surface and conditions habitability of such worlds.
C. O'Neill
A. Lenardic
Geophysical Research Letters
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While I’m all excited about finding exoplanets and all someone needs to remind folks that this is speculative theorizing through and through.
At some point astronomers need to be reminded to actually observe things before reaching conclusions even if that means you cannot reach a conclusion for another a good while.
Next we’ll see speculative theorizing as to the type of architecture the theoretical inhabitants of these exoplanets might have used recently.
stop! you're just giving them ideas...I can hear the grant application papers rustling already...
This is really just a matter of building a model using math and physics, not unlike the (classical) black hole concept.
Or maybe global warming? ;o) Be sure all relevant data are included!
Yes you are right and I do understand what goes into this.
However I do think we stretch it a good bit beyond what is reasonable.
The best part of this particular model is, it could be a century, or more, if ever, before anyone can substantiate or disconfirm it.
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