Re: Relevant - Plate Tectonics Might Only Occur on 0.003% of Planets. That Makes Earth Very Special Indeed.

Le 2024-07-05 à 16:40, a425couple a écrit :
> On 7/4/24 19:25, Dimensional Traveler wrote:
>> On 7/4/2024 4:49 PM, a425couple wrote:
>>> On 7/4/24 12:33, Dimensional Traveler wrote:
>>>> On 7/4/2024 9:54 AM, a425couple wrote:
>>>>> Big DEAL !!
>>>>> So many times greats like Heinlein and Silverberg have written
>>>>> about us going to exoplanets, and it being like Earth.
>>>>> Sorry,,,, NO!
>>>>>
>>>>> from
>>>>> https://www.universetoday.com/167659/plate-tectonics-might-only-occur-on-0-003-of-planets-that-makes-earth-very-special-indeed/
>>>>>
>>>>> Plate tectonics: Image Credit: NASA/Goddard Space Flight Center 
>>>>> Scientific Visualization Studio
>>>>> POSTED ONJULY 2, 2024 BY SCOTT ALAN JOHNSTON
>>>>>
>>> -----------snip-------
>>>>>
>>>>> Go to the citation for the rest ----.
>>>>
>>>> I went to the citation but couldn't find if that 0.003% is of ALL 
>>>> exo-planets or just the Terrestrial/Super-Terrestrial types.
>>>>
>>>
>>> "the rest" of the citation, did not give a lot of specific information.
>>> Hopefully we will see a lot more on this research in the future.
>>>
>> I also think there's a flaw in their basic assumptions.  If you have a 
>> rocky planet with a liquid core/mantle, you are going to have plate 
>> tectonics.
>>
> resending----
> 
> Ahhh,,,, ??
> I do not know about that.  Needs to get more detailed.
> Take Mars, the closest and most explored example.
> It has pretty much lost internal movement,
> thus magnetic waves that protect it from
> solar waves, and the solar wind has wiped off
> most atmosphere, and water.
> 
> Question Does Mars have plate tectonics?
> 
> Mars, it seems, once had active tectonic plates spreading away from 
> long, narrow volcanic rifts, according to two reports in tomorrow's 
> Science (pp.
> https://www.science.org › content › article › past-tecton...
> Past Tectonics on Mars? | Science | AAAS
> 
> Why doesn't Mars have plate tectonics?
> Shaping the Planets: Tectonism
> Like Earth, Venus and Mars are believed to have hot interiors. This 
> means that they are continuing to lose heat. While their surfaces show 
> evidence of recent deformation — tectonism — neither planet has plate 
> tectonic activity because neither planet has a surface divided into plates.
> 
> Shaping the Planets: Tectonism - Lunar and Planetary Institute
> Lunar and Planetary Institute
> 
> What planets have plate tectonics?
> 
> Why Earth is the only planet with plate tectonics - Big Think
> Here in our Solar System, of all the known planets, only Earth — not 
> Mercury, not Venus, and not Mars — is known to possess plate 
> tectonics.Mar 27, 2023
> 
> How Mars Lost Its Magnetic Field—and Then Its Oceans - JSTOR Daily
> JSTOR Daily
> https://daily.jstor.org › how-mars-lost-its-magnetic-field-...
> Search for: Why did Mars lose its magnetic field?
> 
Mars have about the same average density as the Earth, BUT, the radius 
of Mars is about 0.6 Earth radius.
That mean about 0.216 Earth mass and about 0.36 of the surface. This 
resulted in a much faster cooling. It should be noted that the initial 
temperature of the inside of Mars was probably lower as it accumulated 
less energy during it's accretion. That also mean a lot less heat from 
nuclear decay. So, it's interior cooled, causing the core to become 
thick, thus stopping the magnetic field generating process.
The loss of it's magnetic field only accelerated the loss of it's 
atmosphere. Remember that the Martian escape velocity is about a third 
of Earth's escape velocity. That alone mean loosing it's atmosphere.

For Earth, we now have reasons to think that plate tectonics got 
initiated by the collision that formed the Moon. Then, the tidal pull 
from the Moon may have helped kipping it running.
Venus seems to never experience such a collision, so, nothing to kick 
start it's plate tectonics. The Venusian crust it possibly thinner than 
Earth's crust, as the insulation provided by it's very thick atmosphere 
must slow down it's cooling.

There is a model where Mercury would be the core of an Uranus like 
planet that evaporated due to it's proximity to the Sun.