Donate to Remove ads

Got a credit card? use our Credit Card & Finance Calculators

Thanks to johnstevens77,Bhoddhisatva,scotia,Anonymous,Cornytiv34, for Donating to support the site

Super Earths - A Chat

Scientific discovery and discussion
AsleepInYorkshire
Lemon Half
Posts: 7383
Joined: February 7th, 2017, 9:36 pm
Has thanked: 10514 times
Been thanked: 4659 times

Super Earths - A Chat

#346879

Postby AsleepInYorkshire » October 11th, 2020, 10:11 am

Previously the scientific community theorised and therefore, looked for planets outside of our solar system that were similar in size to Earth. If I have understood this correctly they also looked for these planets to be in what they believed were a goldilocks zone, an area thought to be where life would be most likely to thrive.

However, they've had a little review of that. And they now believe there may be planets that are better suited to life than our own Earth. Of course it's highly speculative but it does seem to hold some water, no pun intended.

Super Earths are about 5 time the mass of our own Earth. There gravity is about 1.5 times greater than Earth. But this is sufficient to lower the height of mountain ranges and deep sea trenches. If water exists on a Super Earth it could hold up to 80% more than Earth. The "goldilocks zone" for this planet would probably be much larger than Earth as it will have a higher resistance to radiation from its own sun.

The search is now on to look for Super Earths. And they are looking in specific areas of our galaxy. These are the areas between the spiral arms of our galaxy which is where our placid solar system resides. Also they are looking further away from the centre of our galaxy as this is where radiation peaks and reduces the probability of life.

AiY

Itsallaguess
Lemon Half
Posts: 9129
Joined: November 4th, 2016, 1:16 pm
Has thanked: 4140 times
Been thanked: 10023 times

Re: Super Earths - A Chat

#346883

Postby Itsallaguess » October 11th, 2020, 10:30 am

AsleepInYorkshire wrote:
Super Earths are about 5 time the mass of our own Earth. There gravity is about 1.5 times greater than Earth. But this is sufficient to lower the height of mountain ranges and deep sea trenches. If water exists on a Super Earth it could hold up to 80% more than Earth. The "goldilocks zone" for this planet would probably be much larger than Earth as it will have a higher resistance to radiation from its own sun.

The search is now on to look for Super Earths. And they are looking in specific areas of our galaxy. These are the areas between the spiral arms of our galaxy which is where our placid solar system resides. Also they are looking further away from the centre of our galaxy as this is where radiation peaks and reduces the probability of life.


One of the really opportune things about life on Earth is that the gravitational pull of our planet still allows us, with some real effort, to get into orbit using the fuels we've got available to us..

Did you know that if Earth was around 50% larger, we wouldn't be able to get into orbit using currently-known fuel and technologies?

https://www.realclearscience.com/blog/2017/07/06/if_earth_was_50_larger_we_might_be_stuck_here.html

Which might mean that even if we found a 'Super Earth', we may only be able to land there, with the very real possibility of then never being able to leave...

Some interesting discussions on this here -

https://space.stackexchange.com/questions/14383/how-much-bigger-could-earth-be-before-rockets-wouldnt-work

This is one of the possible reasons behind space itself not being filled with life. If we consider how many ducks need to line up to create the necessary planetary conditions for life in the first place, there's then the additional issue of the size of your planet determining if you'll ever be able to leave it...

Cheers,

Itsallaguess

AsleepInYorkshire
Lemon Half
Posts: 7383
Joined: February 7th, 2017, 9:36 pm
Has thanked: 10514 times
Been thanked: 4659 times

Re: Super Earths - A Chat

#346890

Postby AsleepInYorkshire » October 11th, 2020, 11:03 am

Itsallaguess wrote:Did you know that if Earth was around 50% larger, we wouldn't be able to get into orbit using currently-known fuel and technologies?

https://www.realclearscience.com/blog/2017/07/06/if_earth_was_50_larger_we_might_be_stuck_here.html

Which might mean that even if we found a 'Super Earth', we may only be able to land there, with the very real possibility of then never being able to leave...

Some interesting discussions on this here -

https://space.stackexchange.com/questions/14383/how-much-bigger-could-earth-be-before-rockets-wouldnt-work

This is one of the possible reasons behind space itself not being filled with life. If we consider how many ducks need to line up to create the necessary planetary conditions for life in the first place, there's then the additional issue of the size of your planet determining if you'll ever be able to leave it...

Cheers,

Itsallaguess

I'll see your gravity issue and raise you a space elevator :ugeek:

Not entirely sure but I think this type of technology would be worth considering for gravity based issues. Assuming that is "we've" done all our due diligence before colonisation and we really want to leave afterwards.

First we have to get there though :)

AiY

ursaminortaur
Lemon Half
Posts: 6944
Joined: November 4th, 2016, 3:26 pm
Has thanked: 447 times
Been thanked: 1717 times

Re: Super Earths - A Chat

#346910

Postby ursaminortaur » October 11th, 2020, 12:39 pm

AsleepInYorkshire wrote:
Itsallaguess wrote:Did you know that if Earth was around 50% larger, we wouldn't be able to get into orbit using currently-known fuel and technologies?

https://www.realclearscience.com/blog/2017/07/06/if_earth_was_50_larger_we_might_be_stuck_here.html

Which might mean that even if we found a 'Super Earth', we may only be able to land there, with the very real possibility of then never being able to leave...

Some interesting discussions on this here -

https://space.stackexchange.com/questions/14383/how-much-bigger-could-earth-be-before-rockets-wouldnt-work

This is one of the possible reasons behind space itself not being filled with life. If we consider how many ducks need to line up to create the necessary planetary conditions for life in the first place, there's then the additional issue of the size of your planet determining if you'll ever be able to leave it...

Cheers,

Itsallaguess

I'll see your gravity issue and raise you a space elevator :ugeek:

Not entirely sure but I think this type of technology would be worth considering for gravity based issues. Assuming that is "we've" done all our due diligence before colonisation and we really want to leave afterwards.

First we have to get there though :)

AiY


The problem with building a space elevator is finding a material which is both light enough and strong enough to survive the stresses. On a Super Earth with a higher gravity that problem would become even harder.
The best material we have found so far are carbon nanotubes but they have problems and probably won't work see

https://www.newscientist.com/article/2093356-carbon-nanotubes-too-weak-to-get-a-space-elevator-off-the-ground/

For want of an atom, the space elevator failed.

Carbon nanotubes (CNTs) are famed for being a future wonder material that will enable a swathe of super-strong but light applications from racing bikes to computer components.

But now it seems a single out-of-place atom is enough to cut their strength by more than half. That means one of the more outlandish applications for CNT fibres – a sci-fi space elevator – might never happen.

The tubes’ strength is a result of their atomic structure, with walls made from just a single layer of carbon atoms locked in a hexagonal grid. Theoretical studies suggest that a single CNT can have a tensile strength of 100 gigapascals (GPa), making it one of the strongest materials around, but efforts to spin multiple nanotubes into a practical large-scale fibre have only produced ropes with strengths of 1 GPa.
.
.
.
Estimates suggest such a cable would need a tensile strength of 50 GPa, so CNTs were a promising solution, but Ding’s research suggests they won’t work. “Unless great breakthroughs on CNT synthesis can be achieved, using CNTs to build a space elevator would be extremely challenging,” he says.

Itsallaguess
Lemon Half
Posts: 9129
Joined: November 4th, 2016, 1:16 pm
Has thanked: 4140 times
Been thanked: 10023 times

Re: Super Earths - A Chat

#346912

Postby Itsallaguess » October 11th, 2020, 12:45 pm

AsleepInYorkshire wrote:
Itsallaguess wrote:
Did you know that if Earth was around 50% larger, we wouldn't be able to get into orbit using currently-known fuel and technologies?

https://www.realclearscience.com/blog/2017/07/06/if_earth_was_50_larger_we_might_be_stuck_here.html

Which might mean that even if we found a 'Super Earth', we may only be able to land there, with the very real possibility of then never being able to leave...

Some interesting discussions on this here -

https://space.stackexchange.com/questions/14383/how-much-bigger-could-earth-be-before-rockets-wouldnt-work

This is one of the possible reasons behind space itself not being filled with life. If we consider how many ducks need to line up to create the necessary planetary conditions for life in the first place, there's then the additional issue of the size of your planet determining if you'll ever be able to leave it..


I'll see your gravity issue and raise you a space elevator :ugeek:

Not entirely sure but I think this type of technology would be worth considering for gravity based issues.


They're a great idea, but as far as I'm aware all the proposed space-elevator designs would require 'off-planet' orbital processes to enable them in the first place, given that some sort of 'counterweight' needs to be placed in orbit so that it can act as the geostationary 'orbital mass' that keeps the whole system operational..

Which brings us back to 'Super Earth' gravities perhaps being too strong to get into orbit to put those counterweights up there in the first place....

Cheers,

Itsallaguess

Bubblesofearth
Lemon Quarter
Posts: 1080
Joined: November 8th, 2016, 7:32 am
Has thanked: 8 times
Been thanked: 432 times

Re: Super Earths - A Chat

#346923

Postby Bubblesofearth » October 11th, 2020, 1:22 pm

Itsallaguess wrote:
One of the really opportune things about life on Earth is that the gravitational pull of our planet still allows us, with some real effort, to get into orbit using the fuels we've got available to us..

Did you know that if Earth was around 50% larger, we wouldn't be able to get into orbit using currently-known fuel and technologies?

Itsallaguess


How about if you leave from higher up;

https://www.bbc.co.uk/news/uk-wales-49827415

BoE

ursaminortaur
Lemon Half
Posts: 6944
Joined: November 4th, 2016, 3:26 pm
Has thanked: 447 times
Been thanked: 1717 times

Re: Super Earths - A Chat

#346925

Postby ursaminortaur » October 11th, 2020, 1:25 pm

AsleepInYorkshire wrote:Previously the scientific community theorised and therefore, looked for planets outside of our solar system that were similar in size to Earth. If I have understood this correctly they also looked for these planets to be in what they believed were a goldilocks zone, an area thought to be where life would be most likely to thrive.

However, they've had a little review of that. And they now believe there may be planets that are better suited to life than our own Earth. Of course it's highly speculative but it does seem to hold some water, no pun intended.

Super Earths are about 5 time the mass of our own Earth. There gravity is about 1.5 times greater than Earth. But this is sufficient to lower the height of mountain ranges and deep sea trenches. If water exists on a Super Earth it could hold up to 80% more than Earth. The "goldilocks zone" for this planet would probably be much larger than Earth as it will have a higher resistance to radiation from its own sun.

The search is now on to look for Super Earths. And they are looking in specific areas of our galaxy. These are the areas between the spiral arms of our galaxy which is where our placid solar system resides. Also they are looking further away from the centre of our galaxy as this is where radiation peaks and reduces the probability of life.

AiY


As far as I am aware there are still serious questions to be answered as to the suitability of Super Earths for life. Particularly as to whether they would have plate tectonics and a magnetic field both crucial for life on Earth. Their larger size and gravity are also likely to mean that they have much larger atmospheres and hence pressures at the surface.

https://www.sciencenewsforstudents.org/article/super-earths-not-place-plate-tectonics

The interiors of super-Earths experience supersized pressures. In the new study, Miyagoshi’s team simulated these extreme pressures. That work suggested that these exoplanets probably have thick, stagnant outer shells. Deeper within these planets, gooey rock circulates sluggishly. Those properties make the existence of tectonic plates unlikely, the scientists conclude.


https://horizon-magazine.eu/article/there-life-super-earths-answer-could-lie-their-cores.html

‘Two cores might behave differently, and one might have a magnetic field and the other wouldn’t,’ explained Dr Caracas. ‘A stronger magnetic field gives you better protection on the surface from the sun’s rays, and that means you can make organic molecules that are more complex.’

Dr Guillaume Fiquet, an experimental physicist at CNRS and Sorbonne University in Paris, France, is also trying to understand super-Earth interiors through a project called PLANETDIVE. ‘When people talk about the habitability of planets, this is often related to the presence of a magnetic field, which itself is related to having some kind of metallic core or at least conductive material (in vigorous motion),’ he said.

He is investigating how materials like iron behave under pressures inside super-Earths, which could be up to 1 terapascal, three times the pressure within Earth. This squashes atoms together and can change the properties of materials, meaning that our knowledge about how they behave on Earth may not apply to exoplanets.

‘Exoplanets can be larger planets than Earth, which means the pressures and temperatures could be much greater,’ Dr Fiquet said, ‘That forces us to try to develop new tools to access special states of matter that we don’t know yet.’



https://www.forbes.com/sites/startswithabang/2017/02/16/super-earths-are-common-but-incapable-of-supporting-life-like-ours/#77460cd74188

What they find is that the transition from "rocky" world to "gaseous" world occurs at just twice the Earth's mass. If you're more that twice the mass of Earth and you receive the same amount of energy from your star, you'll be able to hold onto a substantial hydrogen-and-helium envelope of gas, creating an atmospheric pressure that's hundreds or even thousands of times as great as what we have on Earth's surface. The hope that Super-Earth worlds would be Earth-like is shattered, and we can safely put Super-Earths, Mini-Neptunes and Neptune-like worlds into the same overall category.

Hence I'd think it is rather too early to make predictions about Super Earths being better suited to life than our Earth (or for that matter being habitable at all).

There would be other consequences of living on a Super Earth with for instance increased likelihood of volcanic activity and asteroid collisions.

https://www.livescience.com/what-if-super-earth.html

What if Earth were a super-Earth?
.
.
.
With a larger planet and stronger gravitational field, Earth would also experience more collisions, Rory Barnes, a theorist who studies planet habitability at the University of Washington, told Live Science. As a superplanet, Earth's greater gravitational pull would effectively attract more and larger asteroids, so "Armageddon-type" collisions would become more of a concern than they are now, Barnes said.
.
.
.
Barnes also pointed out that a larger interior could make super-Earth more volcanically active than it is now. As the radius of the planet increases, there's more energy inside and fewer places for that energy to escape. More volcanic eruptions wouldn't be surprising, he said.

GrahamPlatt
Lemon Quarter
Posts: 2059
Joined: November 4th, 2016, 9:40 am
Has thanked: 1032 times
Been thanked: 823 times

Re: Super Earths - A Chat

#346984

Postby GrahamPlatt » October 11th, 2020, 6:42 pm

I find this statement in the OP intriguing:
“Super Earths are about 5 time the mass of our own Earth. There gravity is about 1.5 times greater than Earth”.
Assuming that “gravity” there means the force exerted on a body at the planet’s surface.
Given that f = (G.m1.m2)/d^2, why would a body of 5x the mass only have 1.5x the “gravity”?

GrahamPlatt
Lemon Quarter
Posts: 2059
Joined: November 4th, 2016, 9:40 am
Has thanked: 1032 times
Been thanked: 823 times

Re: Super Earths - A Chat

#346989

Postby GrahamPlatt » October 11th, 2020, 7:16 pm

“You can no longer edit or delete that post“. Unfortunate.
Anyway, I’ve been thinking. Evidently the d^2 is more important than either of the Masses. To increase the mass of a sphere 5 fold doesn’t take a large increase in radius. On top of which, there’s the increased density to consider (which would also reduce the radius. I’m not convinced.

dspp
Lemon Half
Posts: 5884
Joined: November 4th, 2016, 10:53 am
Has thanked: 5825 times
Been thanked: 2127 times

Re: Super Earths - A Chat

#346998

Postby dspp » October 11th, 2020, 8:28 pm

GrahamPlatt wrote:“You can no longer edit or delete that post“. Unfortunate.
Anyway, I’ve been thinking. Evidently the d^2 is more important than either of the Masses. To increase the mass of a sphere 5 fold doesn’t take a large increase in radius. On top of which, there’s the increased density to consider (which would also reduce the radius. I’m not convinced.


You are onto something. The density hardly changes, most solids & liquids are (to a first order approximation) incompressible. So do the maths and you will find yourself convinced.

Then go further. Consider that as radius increases, and gravity increases, so the ability to retain the lighter fractions of atmospheric gases increases. It appears to be a size-wise very narrow sweet slot between mini-Uranus and Mars. Too big and you end up with nasty gases dominating the atmosphere, and no chance of achieving escape velocity. Too small and you end up with no atmosphere (at least during an evolutionarily viable timescale). The planet then of course has also to be placed into the sweet zone in orbital terms, too close and it ends up like Venus with thermal runaway (though we don't have a Earth sized planet in a Mars orbit to validate the alternative.

It is a very difficult needle to thread, this viable intelligent life thing. It is not obvious that humans will manage it. With every year we find new terms in the Drake equation.

regards, dspp

Sorcery
Lemon Quarter
Posts: 1229
Joined: November 4th, 2016, 6:38 pm
Has thanked: 147 times
Been thanked: 366 times

Re: Super Earths - A Chat

#346999

Postby Sorcery » October 11th, 2020, 8:55 pm

dspp wrote:
GrahamPlatt wrote:“You can no longer edit or delete that post“. Unfortunate.
Anyway, I’ve been thinking. Evidently the d^2 is more important than either of the Masses. To increase the mass of a sphere 5 fold doesn’t take a large increase in radius. On top of which, there’s the increased density to consider (which would also reduce the radius. I’m not convinced.


You are onto something. The density hardly changes, most solids & liquids are (to a first order approximation) incompressible. So do the maths and you will find yourself convinced.

Then go further. Consider that as radius increases, and gravity increases, so the ability to retain the lighter fractions of atmospheric gases increases. It appears to be a size-wise very narrow sweet slot between mini-Uranus and Mars. Too big and you end up with nasty gases dominating the atmosphere, and no chance of achieving escape velocity. Too small and you end up with no atmosphere (at least during an evolutionarily viable timescale). The planet then of course has also to be placed into the sweet zone in orbital terms, too close and it ends up like Venus with thermal runaway (though we don't have a Earth sized planet in a Mars orbit to validate the alternative.

It is a very difficult needle to thread, this viable intelligent life thing. It is not obvious that humans will manage it. With every year we find new terms in the Drake equation.
=
regards, dspp


Yes I agree, using the volume of a sphere as a proxy for mass (4/3) * pi * r^3, I get a volume of 4.189 for a sphere of radius 1 and a volume of 14.139 for a sphere of radius 1.5. Thats' a 3 and a bit increase in volume and mass, not 5. I am assuming the larger "earth" has the same density and internal temperature distribution. As dspp says solids and liquids are not very compressible but they can be made more dense by a factor of say 2 by halving their temperature in degrees Kelvin.

ursaminortaur
Lemon Half
Posts: 6944
Joined: November 4th, 2016, 3:26 pm
Has thanked: 447 times
Been thanked: 1717 times

Re: Super Earths - A Chat

#347236

Postby ursaminortaur » October 13th, 2020, 2:00 am

Sorcery wrote:
dspp wrote:
GrahamPlatt wrote:“You can no longer edit or delete that post“. Unfortunate.
Anyway, I’ve been thinking. Evidently the d^2 is more important than either of the Masses. To increase the mass of a sphere 5 fold doesn’t take a large increase in radius. On top of which, there’s the increased density to consider (which would also reduce the radius. I’m not convinced.


You are onto something. The density hardly changes, most solids & liquids are (to a first order approximation) incompressible. So do the maths and you will find yourself convinced.

Then go further. Consider that as radius increases, and gravity increases, so the ability to retain the lighter fractions of atmospheric gases increases. It appears to be a size-wise very narrow sweet slot between mini-Uranus and Mars. Too big and you end up with nasty gases dominating the atmosphere, and no chance of achieving escape velocity. Too small and you end up with no atmosphere (at least during an evolutionarily viable timescale). The planet then of course has also to be placed into the sweet zone in orbital terms, too close and it ends up like Venus with thermal runaway (though we don't have a Earth sized planet in a Mars orbit to validate the alternative.

It is a very difficult needle to thread, this viable intelligent life thing. It is not obvious that humans will manage it. With every year we find new terms in the Drake equation.
=
regards, dspp


Yes I agree, using the volume of a sphere as a proxy for mass (4/3) * pi * r^3, I get a volume of 4.189 for a sphere of radius 1 and a volume of 14.139 for a sphere of radius 1.5. Thats' a 3 and a bit increase in volume and mass, not 5. I am assuming the larger "earth" has the same density and internal temperature distribution. As dspp says solids and liquids are not very compressible but they can be made more dense by a factor of say 2 by halving their temperature in degrees Kelvin.


The density of the Earth is far from constant with depth see

https://www.researchgate.net/figure/The-variation-of-density-within-the-Earth-after-Bullen-and-Birch_fig8_228377528

Image

The estimate of a Super Earth of about 5 times the Earth's mass having a radius of about 1.5 times that of Earth may be based on the calculations done for Gliese 581c which with a mass of 5.5 times that of Earth was calculated as having such a radius.

https://en.wikipedia.org/wiki/Gliese_581c

No actual measurement of the radius of Gliese 581c was made but this was calculated making reasonable assumptions for a rocky planet

For example, if Gliese 581c is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth, according to Udry's team.

For other Super Earths both a reasonably estimated mass and radius are available eg

https://en.wikipedia.org/wiki/Kepler-69c

It has an estimated mass of around 6 M⊕ and a radius of 1.71 R⊕.

dspp
Lemon Half
Posts: 5884
Joined: November 4th, 2016, 10:53 am
Has thanked: 5825 times
Been thanked: 2127 times

Re: Super Earths - A Chat

#347413

Postby dspp » October 13th, 2020, 3:16 pm

ursaminortaur wrote:
The density of the Earth is far from constant with depth


Thanks ursa. I meant very little density change due to compression. Composition on the other hand does indeed matter.

regards, dspp

Sorcery
Lemon Quarter
Posts: 1229
Joined: November 4th, 2016, 6:38 pm
Has thanked: 147 times
Been thanked: 366 times

Re: Super Earths - A Chat

#347442

Postby Sorcery » October 13th, 2020, 4:03 pm

ursaminortaur wrote:
Sorcery wrote:
dspp wrote:
You are onto something. The density hardly changes, most solids & liquids are (to a first order approximation) incompressible. So do the maths and you will find yourself convinced.

Then go further. Consider that as radius increases, and gravity increases, so the ability to retain the lighter fractions of atmospheric gases increases. It appears to be a size-wise very narrow sweet slot between mini-Uranus and Mars. Too big and you end up with nasty gases dominating the atmosphere, and no chance of achieving escape velocity. Too small and you end up with no atmosphere (at least during an evolutionarily viable timescale). The planet then of course has also to be placed into the sweet zone in orbital terms, too close and it ends up like Venus with thermal runaway (though we don't have a Earth sized planet in a Mars orbit to validate the alternative.

It is a very difficult needle to thread, this viable intelligent life thing. It is not obvious that humans will manage it. With every year we find new terms in the Drake equation.
=
regards, dspp


Yes I agree, using the volume of a sphere as a proxy for mass (4/3) * pi * r^3, I get a volume of 4.189 for a sphere of radius 1 and a volume of 14.139 for a sphere of radius 1.5. Thats' a 3 and a bit increase in volume and mass, not 5. I am assuming the larger "earth" has the same density and internal temperature distribution. As dspp says solids and liquids are not very compressible but they can be made more dense by a factor of say 2 by halving their temperature in degrees Kelvin.


The density of the Earth is far from constant with depth see

https://www.researchgate.net/figure/The-variation-of-density-within-the-Earth-after-Bullen-and-Birch_fig8_228377528

Image

The estimate of a Super Earth of about 5 times the Earth's mass having a radius of about 1.5 times that of Earth may be based on the calculations done for Gliese 581c which with a mass of 5.5 times that of Earth was calculated as having such a radius.

https://en.wikipedia.org/wiki/Gliese_581c

No actual measurement of the radius of Gliese 581c was made but this was calculated making reasonable assumptions for a rocky planet

For example, if Gliese 581c is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth, according to Udry's team.

For other Super Earths both a reasonably estimated mass and radius are available eg

https://en.wikipedia.org/wiki/Kepler-69c

It has an estimated mass of around 6 M⊕ and a radius of 1.71 R⊕.


I am sure there are planets that differ in the size of the core and density profile with depth from surface. However I was comparing the mass for an earth analogue with a 50% larger radius. If we increase the radius by 1.71 as in your quote for Kepler 69c, the volume does work out at 5 times the earth and therefore for an earth analogue 5 times the mass. If Kepler-69c has a mass of 6 times earth then it's not an earth analogue. I am unsure whether you are saying my reasoning is faulty or not. There are good reasons to think the earth is a unusual though because it's thought that the moon formed from an earth/Theia impact and there was an exchange of materials.
https://en.wikipedia.org/wiki/Giant-imp ... 0coalesced).


Return to “Science”

Who is online

Users browsing this forum: No registered users and 5 guests