Possible Explanations for Earth's Unique Characteristics

  • Thread starter Loren Booda
  • Start date
  • Tags
    Earth
In summary: Mercury... without moons really like Earth? Without a large, stabilizing moon, Mercury, Venus and Mars all experience much larger variations in axial obliquity--Venus has turned itself nearly completely upside down!
  • #36
Ophiolite said:
Plate tectonics. ... or a periodic catastrophic affair as on Venus.


What evidence is there to substantiate that the apparent catastrophic affair on Venus was periodic, rather than unique, one time only?
 
Earth sciences news on Phys.org
  • #37
There are two principal options:
1. The resurfacing event that occurred around 600 million years ago and the stagnant lid period that preceded it, were themselves preceded by 'conventional' plate tectonics.
2. The resurfacing event etc, was the most recent in a series of such events.

You have to dispose of the internal heat. These are the two obvious mechanisms. I have a gut feel - unquantified - that continuous conventional plate tectonics should have maintained water content on the planet, so I lean to the possibility of periodic resurfacing. The evidence is consisten with either.
 
  • #38
Richard111 said:
Ooops, yes. Solar tides. But would that have been sufficient to maintain spin stabilisation? Would the limited range of solar tides have encouraged life to adapt to less exposed land surfaces?
AFAIK, the tides are not the mechanism by which the Moon aids in keeping the Earth's rotation stable. Tides are dissipative forces. The same gravity gradient forces that cause the tides also induce a conservative torque on the Earth as a whole. This torque, averaged out over the Moon's 18.6 year nodical period, results in the 26,000 year lunisolar precession.


Richard111 said:
Without the moon, life as we know it may not have been possible.
Emphasis mine. This is purely conjectural.


Richard111 said:
wikipedia said:
There is geological and paleontological evidence that the Earth rotated faster and that the Moon was closer to the Earth in the remote past.
I am not debating that the Moon slows the Earth's rotation rate. That is a fact. What is debatable is whether the Earth's day would be eight hours long if the Moon never existed. If indeed the Moon formed from a collision between the Earth and Theia, we do not know how much the collision itself changed the Earth's rotation rate.
 
  • #39
Ophiolite said:
There are two principal options:
1. The resurfacing event that occurred around 600 million years ago and the stagnant lid period that preceded it, were themselves preceded by 'conventional' plate tectonics.
2. The resurfacing event etc, was the most recent in a series of such events.

You have to dispose of the internal heat. These are the two obvious mechanisms. I have a gut feel - unquantified - that continuous conventional plate tectonics should have maintained water content on the planet, so I lean to the possibility of periodic resurfacing. The evidence is consisten with either.

but these are still suppositions following assumptions about heat and heat production in the core, which are also hypotheses. How many times did Venus lose its spinning energy for instance (due to the chaotic zone)? and how about possible relationships there?
 
Last edited:
  • #40
Andre said:
but these are still suppositions following assumptions about heat and heat production in the core, which are also hypotheses.
There are no assumptions here, only reasonable deductions leading to plausible hypotheses.
You will note in an earlier post I talk of two principal explanations. I do not rule out other possibilities, but simply find these two are the most probable based upon our current understanding.

Since I also think Venus suffered one or more catastrophic collisions akin to what formed the moon, or stripped mantle from Mercury, then issues of angular momentum cease to be insoluble problems.
 

Similar threads

Replies
20
Views
3K
Replies
12
Views
5K
  • Earth Sciences
Replies
9
Views
2K
  • Earth Sciences
Replies
7
Views
1K
Replies
3
Views
1K
Replies
22
Views
659
  • Sci-Fi Writing and World Building
Replies
21
Views
853
  • Astronomy and Astrophysics
Replies
1
Views
1K
  • Astronomy and Astrophysics
Replies
15
Views
1K
Replies
2
Views
3K
Back
Top