<p>Most notably, a moving Lithosphere. Shaving off the surface 20km (Lithosphere is~120km) would not stop plate tectonics. What makes Earth's surface so different is that it has a constant cycling of lithosphere; Dead planets are forced to keep surface scars caused by major impacts and weathering. To this date, we have not found another example of plate tectonics, though our ability to confirm this on other planetary bodies is limited. </p>

CC BY-SA 3.0
2014-05-04T04:38:44.483Z
What about [Venus](http://www3.imperial.ac.uk/earthscienceandengineering/research/iarc/theplanets/platetectonicsonvenus)?
blunders
CC BY-SA 3.0
2014-05-04T04:48:59.477Z
There is some debate whether Venus had plate tectonics in the past; I'm a skeptic, as I think venus is a bit too hot. What is not up for debate is that the planet is currently dead.
Neo
CC BY-SA 3.0
2014-05-04T04:50:43.913Z
So, in theory, if it was proven that Venus had plate tectonics in the past - (and the aspects note in the question where excluded) - then there is nothing special, right?
blunders
CC BY-SA 3.0
2014-05-04T04:58:18.817Z
Well, not exactly. Even if Venus had plate tectonics, It's lithosphere is buoyant because of the surface temperature. Earth's lithosphere would still be cold, because of how far away it is from the Sun. So venus might have had moving plates, but it would look more like continental Earth, and not ring of fire earth.
Neo
CC BY-SA 3.0
2014-05-04T05:12:41.650Z
Also, see "[UCLA scientist discovers plate tectonics on Mars](http://newsroom.ucla.edu/releases/ucla-scientist-discovers-plate-237303?link_page_rss=237303)," any comments?
blunders
CC BY-SA 3.0
2014-05-04T05:22:25.117Z
Of course I've read that article, and while Mars may have plate tectonics, it's a rather novel idea. It should be treated with much care, because there are other ideas that are still not fully accepted that are much older (mantle plumes, for example).
Neo
CC BY-SA 3.0
2014-05-04T14:13:08.003Z
*Most notably, a moving Lithosphere* ... and an active and strong magnetic field. Venus and Mars have virtually no magnetic field. Mercury does have one, but it's only about 1/100 as strong as that of the Earth. Regarding a moving lithosphere, water has long been regarded as an important lubricant for plate tectonics. Would we have plate tectonics w/out oceans? (but also see [Fei et al., "Small effect of water on upper-mantle rheology based on silicon self-diffusion coefficients," *Nature* 498, 213–215 (2013)](http://www.nature.com/nature/journal/v498/n7453/abs/nature12193.html)).
David Hammen
CC BY-SA 3.0
2014-05-04T18:47:04.687Z
I think its unclear about the water and the plate tectonics David. While I understand the argument, in my computer simulations I haven't needed to account for water content (or the crust) to get viscous decoupling between two plates. The most important factors seem to be the kinematics and the buoyancy of the plates. Surely the surface would eventually cool. Also, there are other planetary bodies with magnetic fields, like ganymede. Either way, the "Rare Earth" theory provides many ways that the Earth might be unique, and that it includes its interior.
Neo
CC BY-SA 3.0
2014-09-10T08:01:58.883Z
NASA reckons there's [plate tectonics on titan](http://www.nasa.gov/mission_pages/cassini/multimedia/pia10654.html), which granted, is not a planet, but if Jupiter were only slightly larger, it probably would be... ("unique" is such a ... *pointless* word in this context, especially since we only have 8 or 9 planets that we can inspect in any detail...)
naught101
CC BY-SA 3.0
2014-09-10T15:15:09.030Z
Also a paper in nat geo suggests they see proof of subduction on Europa.... Came out 3 days ago
Neo
CC BY-SA 3.0
2014-05-04T04:25:15.677Z
2014-05-04T18:40:21.897Z
2014-05-04T18:40:21.897Z
Neo
<p>Realize that comparing planets is hard, but is Earth really that unique?</p>

<p>More to the point, if everything say 20-km below sea-level up into the exosphere disappeared (and the moon too) - what would be left to differentiate Earth from other planets?</p>

<p><img src="https://i.sstatic.net/6EcMN.jpg" alt="enter image description here"> </p>

CC BY-SA 3.0
2014-05-04T09:38:47.497Z
Special is such a loaded term, unique might be preferable.
Siv
CC BY-SA 3.0
2014-05-04T18:29:13.707Z
I would prefer if we would stick to metric units. Also you accepted the first answer given only one hour after you asked. For a broad question like this, I would at least leave it open a few days. You are effectively silencing a whole set of different opinions a broad question like this could have attracted.
tobias47n9e
CC BY-SA 3.0
2014-05-04T18:38:23.960Z
@Spießbürger: **(1)** Switched it to metric units. **(2)** Post a better answer, and I'll select it, otherwise, I don't see the point in speculating that better answers might have been posted if I had waited to select an answer; the answer selected can always be changed.
blunders
<planetary-science><rare-earth>
Is the majority of Earth not unique?
blunders
# Is the majority of Earth not unique?

(Asked by: username_0 on 2014-05-04)

Realize that comparing planets is hard, but is Earth really that unique?

More to the point, if everything say 20-km below sea-level up into the exosphere disappeared (and the moon too) - what would be left to differentiate Earth from other planets?

![enter image description here](https://i.sstatic.net/6EcMN.jpg)

**Tags:** planetary-science, rare-earth

> **Comments:**
> **username_1**: Special is such a loaded term, unique might be preferable.  
> **username_2**: I would prefer if we would stick to metric units. Also you accepted the first answer given only one hour after you asked. For a broad question like this, I would at least leave it open a few days. You are effectively silencing a whole set of different opinions a broad question like this could have attracted.  
> **username_0**: @Spießbürger: **(1)** Switched it to metric units. **(2)** Post a better answer, and I'll select it, otherwise, I don't see the point in speculating that better answers might have been posted if I had waited to select an answer; the answer selected can always be changed.  

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## 1 answers

### Answer by username_3 on 2014-05-04. Score: 8 | Accepted answer

Most notably, a moving Lithosphere. Shaving off the surface 20km (Lithosphere is~120km) would not stop plate tectonics. What makes Earth's surface so different is that it has a constant cycling of lithosphere; Dead planets are forced to keep surface scars caused by major impacts and weathering. To this date, we have not found another example of plate tectonics, though our ability to confirm this on other planetary bodies is limited.

> **Comments:**
> **username_0**: What about [Venus](http://www3.imperial.ac.uk/earthscienceandengineering/research/iarc/theplanets/platetectonicsonvenus)?  
> **username_3**: There is some debate whether Venus had plate tectonics in the past; I'm a skeptic, as I think venus is a bit too hot. What is not up for debate is that the planet is currently dead.  
> **username_0**: So, in theory, if it was proven that Venus had plate tectonics in the past - (and the aspects note in the question where excluded) - then there is nothing special, right?  
> **username_3**: Well, not exactly. Even if Venus had plate tectonics, It's lithosphere is buoyant because of the surface temperature. Earth's lithosphere would still be cold, because of how far away it is from the Sun. So venus might have had moving plates, but it would look more like continental Earth, and not ring of fire earth.  
> **username_0**: Also, see "[UCLA scientist discovers plate tectonics on Mars](http://newsroom.ucla.edu/releases/ucla-scientist-discovers-plate-237303?link_page_rss=237303)," any comments?  
> **username_3**: Of course I've read that article, and while Mars may have plate tectonics, it's a rather novel idea. It should be treated with much care, because there are other ideas that are still not fully accepted that are much older (mantle plumes, for example).  
> **username_4**: *Most notably, a moving Lithosphere* ... and an active and strong magnetic field. Venus and Mars have virtually no magnetic field. Mercury does have one, but it's only about 1/100 as strong as that of the Earth. Regarding a moving lithosphere, water has long been regarded as an important lubricant for plate tectonics. Would we have plate tectonics w/out oceans? (but also see [Fei et al., "Small effect of water on upper-mantle rheology based on silicon self-diffusion coefficients," *Nature* 498, 213–215 (2013)](http://www.nature.com/nature/journal/v498/n7453/abs/nature12193.html)).  
> **username_3**: I think its unclear about the water and the plate tectonics username_4. While I understand the argument, in my computer simulations I haven't needed to account for water content (or the crust) to get viscous decoupling between two plates. The most important factors seem to be the kinematics and the buoyancy of the plates. Surely the surface would eventually cool. Also, there are other planetary bodies with magnetic fields, like ganymede. Either way, the "Rare Earth" theory provides many ways that the Earth might be unique, and that it includes its interior.  
> **username_5**: NASA reckons there's [plate tectonics on titan](http://www.nasa.gov/mission_pages/cassini/multimedia/pia10654.html), which granted, is not a planet, but if Jupiter were only slightly larger, it probably would be... ("unique" is such a ... *pointless* word in this context, especially since we only have 8 or 9 planets that we can inspect in any detail...)  
> **username_3**: Also a paper in nat geo suggests they see proof of subduction on Europa.... Came out 3 days ago  

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