How to make a bigger planet be as similar to Earth as possible












4














My fantasy world is slightly larger than earth so that discovery of the continents becomes harder (about 20% surface should do it). But at the same time I want to preserve most aspects to make it like the earth, it has a moon, similar animal species, similar climate, four seasons, temperatures ranging from 50C to -60 or so, magnetic field etc. Also similar proportion of minerals in the crust. To achieve this I thought of making the planet spin faster and it's tilt angle to be slightly lesser. Would that work?



How would the increased weight come into play? Would density of the inner mantles be important to preserve or could we make them more porous so to keep 1G without much changes in the surface? Would we still have the same tectonic activity or should we change the nature or thickness of the crust? Would the climate change a lot or the scale of the cyclon/anticyclone system would remain the same? Should I make the atmosfhere lighter?



Any other solutions will be welcomed.
I found this post very useful.










share|improve this question
























  • Done and thanks!
    – Tomás
    Dec 9 at 21:51










  • How big do you want it?
    – Vincent
    Dec 9 at 22:05










  • Edited (about 20%), thank you for your question Vincent.
    – Tomás
    Dec 9 at 22:09










  • +20% area or radius of planet?
    – Artemijs Danilovs
    Dec 9 at 22:27
















4














My fantasy world is slightly larger than earth so that discovery of the continents becomes harder (about 20% surface should do it). But at the same time I want to preserve most aspects to make it like the earth, it has a moon, similar animal species, similar climate, four seasons, temperatures ranging from 50C to -60 or so, magnetic field etc. Also similar proportion of minerals in the crust. To achieve this I thought of making the planet spin faster and it's tilt angle to be slightly lesser. Would that work?



How would the increased weight come into play? Would density of the inner mantles be important to preserve or could we make them more porous so to keep 1G without much changes in the surface? Would we still have the same tectonic activity or should we change the nature or thickness of the crust? Would the climate change a lot or the scale of the cyclon/anticyclone system would remain the same? Should I make the atmosfhere lighter?



Any other solutions will be welcomed.
I found this post very useful.










share|improve this question
























  • Done and thanks!
    – Tomás
    Dec 9 at 21:51










  • How big do you want it?
    – Vincent
    Dec 9 at 22:05










  • Edited (about 20%), thank you for your question Vincent.
    – Tomás
    Dec 9 at 22:09










  • +20% area or radius of planet?
    – Artemijs Danilovs
    Dec 9 at 22:27














4












4








4







My fantasy world is slightly larger than earth so that discovery of the continents becomes harder (about 20% surface should do it). But at the same time I want to preserve most aspects to make it like the earth, it has a moon, similar animal species, similar climate, four seasons, temperatures ranging from 50C to -60 or so, magnetic field etc. Also similar proportion of minerals in the crust. To achieve this I thought of making the planet spin faster and it's tilt angle to be slightly lesser. Would that work?



How would the increased weight come into play? Would density of the inner mantles be important to preserve or could we make them more porous so to keep 1G without much changes in the surface? Would we still have the same tectonic activity or should we change the nature or thickness of the crust? Would the climate change a lot or the scale of the cyclon/anticyclone system would remain the same? Should I make the atmosfhere lighter?



Any other solutions will be welcomed.
I found this post very useful.










share|improve this question















My fantasy world is slightly larger than earth so that discovery of the continents becomes harder (about 20% surface should do it). But at the same time I want to preserve most aspects to make it like the earth, it has a moon, similar animal species, similar climate, four seasons, temperatures ranging from 50C to -60 or so, magnetic field etc. Also similar proportion of minerals in the crust. To achieve this I thought of making the planet spin faster and it's tilt angle to be slightly lesser. Would that work?



How would the increased weight come into play? Would density of the inner mantles be important to preserve or could we make them more porous so to keep 1G without much changes in the surface? Would we still have the same tectonic activity or should we change the nature or thickness of the crust? Would the climate change a lot or the scale of the cyclon/anticyclone system would remain the same? Should I make the atmosfhere lighter?



Any other solutions will be welcomed.
I found this post very useful.







earth-like climate geography geology astrophysics






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Dec 9 at 22:52

























asked Dec 9 at 19:19









Tomás

3179




3179












  • Done and thanks!
    – Tomás
    Dec 9 at 21:51










  • How big do you want it?
    – Vincent
    Dec 9 at 22:05










  • Edited (about 20%), thank you for your question Vincent.
    – Tomás
    Dec 9 at 22:09










  • +20% area or radius of planet?
    – Artemijs Danilovs
    Dec 9 at 22:27


















  • Done and thanks!
    – Tomás
    Dec 9 at 21:51










  • How big do you want it?
    – Vincent
    Dec 9 at 22:05










  • Edited (about 20%), thank you for your question Vincent.
    – Tomás
    Dec 9 at 22:09










  • +20% area or radius of planet?
    – Artemijs Danilovs
    Dec 9 at 22:27
















Done and thanks!
– Tomás
Dec 9 at 21:51




Done and thanks!
– Tomás
Dec 9 at 21:51












How big do you want it?
– Vincent
Dec 9 at 22:05




How big do you want it?
– Vincent
Dec 9 at 22:05












Edited (about 20%), thank you for your question Vincent.
– Tomás
Dec 9 at 22:09




Edited (about 20%), thank you for your question Vincent.
– Tomás
Dec 9 at 22:09












+20% area or radius of planet?
– Artemijs Danilovs
Dec 9 at 22:27




+20% area or radius of planet?
– Artemijs Danilovs
Dec 9 at 22:27










1 Answer
1






active

oldest

votes


















6














Gravity:
Without some sort of unobtanium it will be difficult to substantially increase the diameter of an earth-like wold without also substantially increasing its surface gravity.



If you replace most/all of the iron in the core with lighter materials like silicates and magnesium, you might be able to reduce the density of the core by ~50%. But as the core only makes up about 10% by volume, this would only reduce the average density by around 5% - assuming this could still produce a planet with a crust still containing substantial amounts of iron and other heavy elements as found on the earth. You could possibly do a little bit better by changing the ratio of silicon to other elements, but probably only a couple more percent difference in density. Voids and porosity won't work - at the sort of pressures you find in the core there are no voids. You could go a bit more extreme by replacing substantial amounts of silicon and similar elements with water, carbon and other lighter materials. This could reduce density substantially, but now the crust (and the tectonics) is definitely not going to resemble that of earth (maybe substantial engineering by a super-civilization could get you a reasonable approximation - but it would not form 'naturally').



So assuming a density 7-10% less than that of the earth, surface gravity scales as density $times$ radius2. So if you allowed for surface gravity to be maybe 10% higher than earth's (is that similar enough?) - you could get away with approximately 10% greater radius. This would provide you with ~30% more surface area. If you want to retain ~1g then you are probably limited to radius increase of no more than 4-5% without weird global engineering.



Spinning faster:
Spinning faster won't help reduce surface gravity unless you spin ridiculously fast - 20 minute days anyone?



Tilt:
Increasing the tilt angle would make the climate more extreme (possibly much more extreme). And as a larger world would likely have more extreme weather anyway (more space for thermal gradients etc to develop), you would likely get a pretty stormy climate with much higher average wind speed. Perhaps that will help you get what you want - a slightly bigger planet with a slightly higher frequency of horrible weather would indeed be harder to explore.



As an added note - re-positioning the continents can also make things more difficult for exploration. If the Pacific was narrowed by 30% then the Atlantic could be widened by ~50% (without significantly altering the shape of the continents). This would have made it harder/impossible for Columbus etc. to have 'discovered' the new world (which could have led to at least a century delay till it was found by Europeans).






share|improve this answer























  • Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
    – Tomás
    Dec 9 at 21:07








  • 2




    It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
    – eyeballfrog
    Dec 10 at 1:19












  • @eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
    – Penguino
    Dec 10 at 1:58










  • Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
    – spcan
    Dec 10 at 11:21










  • And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
    – Penguino
    Dec 10 at 20:14











Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "579"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fworldbuilding.stackexchange.com%2fquestions%2f132448%2fhow-to-make-a-bigger-planet-be-as-similar-to-earth-as-possible%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









6














Gravity:
Without some sort of unobtanium it will be difficult to substantially increase the diameter of an earth-like wold without also substantially increasing its surface gravity.



If you replace most/all of the iron in the core with lighter materials like silicates and magnesium, you might be able to reduce the density of the core by ~50%. But as the core only makes up about 10% by volume, this would only reduce the average density by around 5% - assuming this could still produce a planet with a crust still containing substantial amounts of iron and other heavy elements as found on the earth. You could possibly do a little bit better by changing the ratio of silicon to other elements, but probably only a couple more percent difference in density. Voids and porosity won't work - at the sort of pressures you find in the core there are no voids. You could go a bit more extreme by replacing substantial amounts of silicon and similar elements with water, carbon and other lighter materials. This could reduce density substantially, but now the crust (and the tectonics) is definitely not going to resemble that of earth (maybe substantial engineering by a super-civilization could get you a reasonable approximation - but it would not form 'naturally').



So assuming a density 7-10% less than that of the earth, surface gravity scales as density $times$ radius2. So if you allowed for surface gravity to be maybe 10% higher than earth's (is that similar enough?) - you could get away with approximately 10% greater radius. This would provide you with ~30% more surface area. If you want to retain ~1g then you are probably limited to radius increase of no more than 4-5% without weird global engineering.



Spinning faster:
Spinning faster won't help reduce surface gravity unless you spin ridiculously fast - 20 minute days anyone?



Tilt:
Increasing the tilt angle would make the climate more extreme (possibly much more extreme). And as a larger world would likely have more extreme weather anyway (more space for thermal gradients etc to develop), you would likely get a pretty stormy climate with much higher average wind speed. Perhaps that will help you get what you want - a slightly bigger planet with a slightly higher frequency of horrible weather would indeed be harder to explore.



As an added note - re-positioning the continents can also make things more difficult for exploration. If the Pacific was narrowed by 30% then the Atlantic could be widened by ~50% (without significantly altering the shape of the continents). This would have made it harder/impossible for Columbus etc. to have 'discovered' the new world (which could have led to at least a century delay till it was found by Europeans).






share|improve this answer























  • Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
    – Tomás
    Dec 9 at 21:07








  • 2




    It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
    – eyeballfrog
    Dec 10 at 1:19












  • @eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
    – Penguino
    Dec 10 at 1:58










  • Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
    – spcan
    Dec 10 at 11:21










  • And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
    – Penguino
    Dec 10 at 20:14
















6














Gravity:
Without some sort of unobtanium it will be difficult to substantially increase the diameter of an earth-like wold without also substantially increasing its surface gravity.



If you replace most/all of the iron in the core with lighter materials like silicates and magnesium, you might be able to reduce the density of the core by ~50%. But as the core only makes up about 10% by volume, this would only reduce the average density by around 5% - assuming this could still produce a planet with a crust still containing substantial amounts of iron and other heavy elements as found on the earth. You could possibly do a little bit better by changing the ratio of silicon to other elements, but probably only a couple more percent difference in density. Voids and porosity won't work - at the sort of pressures you find in the core there are no voids. You could go a bit more extreme by replacing substantial amounts of silicon and similar elements with water, carbon and other lighter materials. This could reduce density substantially, but now the crust (and the tectonics) is definitely not going to resemble that of earth (maybe substantial engineering by a super-civilization could get you a reasonable approximation - but it would not form 'naturally').



So assuming a density 7-10% less than that of the earth, surface gravity scales as density $times$ radius2. So if you allowed for surface gravity to be maybe 10% higher than earth's (is that similar enough?) - you could get away with approximately 10% greater radius. This would provide you with ~30% more surface area. If you want to retain ~1g then you are probably limited to radius increase of no more than 4-5% without weird global engineering.



Spinning faster:
Spinning faster won't help reduce surface gravity unless you spin ridiculously fast - 20 minute days anyone?



Tilt:
Increasing the tilt angle would make the climate more extreme (possibly much more extreme). And as a larger world would likely have more extreme weather anyway (more space for thermal gradients etc to develop), you would likely get a pretty stormy climate with much higher average wind speed. Perhaps that will help you get what you want - a slightly bigger planet with a slightly higher frequency of horrible weather would indeed be harder to explore.



As an added note - re-positioning the continents can also make things more difficult for exploration. If the Pacific was narrowed by 30% then the Atlantic could be widened by ~50% (without significantly altering the shape of the continents). This would have made it harder/impossible for Columbus etc. to have 'discovered' the new world (which could have led to at least a century delay till it was found by Europeans).






share|improve this answer























  • Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
    – Tomás
    Dec 9 at 21:07








  • 2




    It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
    – eyeballfrog
    Dec 10 at 1:19












  • @eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
    – Penguino
    Dec 10 at 1:58










  • Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
    – spcan
    Dec 10 at 11:21










  • And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
    – Penguino
    Dec 10 at 20:14














6












6








6






Gravity:
Without some sort of unobtanium it will be difficult to substantially increase the diameter of an earth-like wold without also substantially increasing its surface gravity.



If you replace most/all of the iron in the core with lighter materials like silicates and magnesium, you might be able to reduce the density of the core by ~50%. But as the core only makes up about 10% by volume, this would only reduce the average density by around 5% - assuming this could still produce a planet with a crust still containing substantial amounts of iron and other heavy elements as found on the earth. You could possibly do a little bit better by changing the ratio of silicon to other elements, but probably only a couple more percent difference in density. Voids and porosity won't work - at the sort of pressures you find in the core there are no voids. You could go a bit more extreme by replacing substantial amounts of silicon and similar elements with water, carbon and other lighter materials. This could reduce density substantially, but now the crust (and the tectonics) is definitely not going to resemble that of earth (maybe substantial engineering by a super-civilization could get you a reasonable approximation - but it would not form 'naturally').



So assuming a density 7-10% less than that of the earth, surface gravity scales as density $times$ radius2. So if you allowed for surface gravity to be maybe 10% higher than earth's (is that similar enough?) - you could get away with approximately 10% greater radius. This would provide you with ~30% more surface area. If you want to retain ~1g then you are probably limited to radius increase of no more than 4-5% without weird global engineering.



Spinning faster:
Spinning faster won't help reduce surface gravity unless you spin ridiculously fast - 20 minute days anyone?



Tilt:
Increasing the tilt angle would make the climate more extreme (possibly much more extreme). And as a larger world would likely have more extreme weather anyway (more space for thermal gradients etc to develop), you would likely get a pretty stormy climate with much higher average wind speed. Perhaps that will help you get what you want - a slightly bigger planet with a slightly higher frequency of horrible weather would indeed be harder to explore.



As an added note - re-positioning the continents can also make things more difficult for exploration. If the Pacific was narrowed by 30% then the Atlantic could be widened by ~50% (without significantly altering the shape of the continents). This would have made it harder/impossible for Columbus etc. to have 'discovered' the new world (which could have led to at least a century delay till it was found by Europeans).






share|improve this answer














Gravity:
Without some sort of unobtanium it will be difficult to substantially increase the diameter of an earth-like wold without also substantially increasing its surface gravity.



If you replace most/all of the iron in the core with lighter materials like silicates and magnesium, you might be able to reduce the density of the core by ~50%. But as the core only makes up about 10% by volume, this would only reduce the average density by around 5% - assuming this could still produce a planet with a crust still containing substantial amounts of iron and other heavy elements as found on the earth. You could possibly do a little bit better by changing the ratio of silicon to other elements, but probably only a couple more percent difference in density. Voids and porosity won't work - at the sort of pressures you find in the core there are no voids. You could go a bit more extreme by replacing substantial amounts of silicon and similar elements with water, carbon and other lighter materials. This could reduce density substantially, but now the crust (and the tectonics) is definitely not going to resemble that of earth (maybe substantial engineering by a super-civilization could get you a reasonable approximation - but it would not form 'naturally').



So assuming a density 7-10% less than that of the earth, surface gravity scales as density $times$ radius2. So if you allowed for surface gravity to be maybe 10% higher than earth's (is that similar enough?) - you could get away with approximately 10% greater radius. This would provide you with ~30% more surface area. If you want to retain ~1g then you are probably limited to radius increase of no more than 4-5% without weird global engineering.



Spinning faster:
Spinning faster won't help reduce surface gravity unless you spin ridiculously fast - 20 minute days anyone?



Tilt:
Increasing the tilt angle would make the climate more extreme (possibly much more extreme). And as a larger world would likely have more extreme weather anyway (more space for thermal gradients etc to develop), you would likely get a pretty stormy climate with much higher average wind speed. Perhaps that will help you get what you want - a slightly bigger planet with a slightly higher frequency of horrible weather would indeed be harder to explore.



As an added note - re-positioning the continents can also make things more difficult for exploration. If the Pacific was narrowed by 30% then the Atlantic could be widened by ~50% (without significantly altering the shape of the continents). This would have made it harder/impossible for Columbus etc. to have 'discovered' the new world (which could have led to at least a century delay till it was found by Europeans).







share|improve this answer














share|improve this answer



share|improve this answer








edited Dec 10 at 1:53









Renan

42.7k1198217




42.7k1198217










answered Dec 9 at 20:41









Penguino

6267




6267












  • Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
    – Tomás
    Dec 9 at 21:07








  • 2




    It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
    – eyeballfrog
    Dec 10 at 1:19












  • @eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
    – Penguino
    Dec 10 at 1:58










  • Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
    – spcan
    Dec 10 at 11:21










  • And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
    – Penguino
    Dec 10 at 20:14


















  • Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
    – Tomás
    Dec 9 at 21:07








  • 2




    It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
    – eyeballfrog
    Dec 10 at 1:19












  • @eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
    – Penguino
    Dec 10 at 1:58










  • Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
    – spcan
    Dec 10 at 11:21










  • And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
    – Penguino
    Dec 10 at 20:14
















Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
– Tomás
Dec 9 at 21:07






Thanks for the answer, it's practically perfect, I didn't intend more than 30% more of surface. Spinning faster is about the day/night cycle, not gravity. Tilt, I guess I got it backwards, shouldn't it be useful to compensate the extreme wheather? The occasional horrible weather could fit perfectly.
– Tomás
Dec 9 at 21:07






2




2




It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
– eyeballfrog
Dec 10 at 1:19






It turns out that planetary size doesn't affect surface gravity all that much once you get larger than Venus. The planet will likely have ~1g even if it is significantly larger than Earth.
– eyeballfrog
Dec 10 at 1:19














@eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
– Penguino
Dec 10 at 1:58




@eyeballfrog A careful reading of that paper shows that this is only true for 'transitional' super-earth type planets that fit between rocky earth-like planets and gas giants. The reason is that most 'super-earths' have a very significant atmosphere so the effective planetary radius increases more quickly with mass. But these super-earths bear little resemblance to our planet - the 'surface' is measured at the gas surface. If you stick with rocky planets with an atmosphere approximately comparable to ours (say no more than 10-20 km deep), surface gravity will scale as I suggested.
– Penguino
Dec 10 at 1:58












Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
– spcan
Dec 10 at 11:21




Great answer and very thorough! +1 Just to comment on the spin, faster spinning to compensate gravity would make traveling north or south impossible, as the centrifugal forces get reduced the further from the equator you are. Also I think Coriolis forces would be quite significant.
– spcan
Dec 10 at 11:21












And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
– Penguino
Dec 10 at 20:14




And if it really was spinning sufficiently fast to make a significant diffidence to surface gravity it would be very noticeably oblate...
– Penguino
Dec 10 at 20:14


















draft saved

draft discarded




















































Thanks for contributing an answer to Worldbuilding Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.





Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


Please pay close attention to the following guidance:


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fworldbuilding.stackexchange.com%2fquestions%2f132448%2fhow-to-make-a-bigger-planet-be-as-similar-to-earth-as-possible%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

"Incorrect syntax near the keyword 'ON'. (on update cascade, on delete cascade,)

Alcedinidae

RAC Tourist Trophy