/sci/ - Science & Math

[Anonymous No.10731811]

Is it possible for a planet to have a significantly greater surface area than the Earth, and thus more habitable area, but still have gravity that’s about the same as Earth?

[Anonymous No.10731819]

>>10731811
A rocky planet with Earth-like composition would have roughly similar density, thus being roughly the same size.
>more habitable area
Most of the Earth surface is inhabitable, in the first place.

[Anonymous No.10731841]

>>10731811
lets rephrase the question: how would you arrange continents and oceans on an Earth-like planet in order to maximize habitable area (no deserts, minimal ocean and iceberg surface)

[Anonymous No.10731929]

>>10731841
moving the continents around wont change the dry surface area. the answer is to have less ocean.

[Anonymous No.10731969]

>>10731811

[Anonymous No.10731993]

>>10731929
If you had less water things would be really bad.
The correct action is to make water habitable.
I wonder if you could light a fire in super oxygenated water?

[Anonymous No.10732009]

>>10731993
I'm a tard it's not regular water in liquid breathing

[Anonymous No.10732012]

>how to increase the surface area of a round object, without altering it's mass

Wrinkles bro.

[Anonymous No.10732029]

>>10732012
now that I think about it, has anyone ever measured the surface area (hills included) of a mountainous state and compared it with it's apparent surface area you'd measure on a map?

I wonder how much discrepancy there is with what's measured on a map and the amount of land (surface area) that exists in real life for states that exist in mountain ranges. Maybe some states in the US that we think of as really small, are in realty as big as Texas because of all the elevation changes.

[Anonymous No.10732035]

>>10732012
>what is density

[Anonymous No.10732042]

>>10732035
adding wrinkles doesn't change it's density tho
gravity should be unaffected as well

[Anonymous No.10732043]

>>10731811
>Is it possible for a planet to have a significantly greater surface area than the Earth, and thus more habitable area, but still have gravity that’s about the same as Earth?
Yes, it just has to be less dense. Note that gravity decays with radius, so you must make sure the increase in volume allows the acceleration at surface to be g.

[Anonymous No.10732077]

>>10732042
Oh right, didn't realize you meant that. Colonizing the volume of mountains is indeed an option, as well as the ocean's surface/floor.

[Anonymous No.10732102]

>>10732077
https://en.wikipedia.org/wiki/Coastline_paradox

In theory, you could have infinite surface area. ..... in theory anyway.

[Anonymous No.10732132]

>>10731811
have you heard of things called multi-floored buildings? or caves?

[Anonymous No.10732137]

>>10732102
Yes but not in terms of habitability. You could increase the raw surface area by many orders of magnitude by creating wrinkles on the nanometer scale but this wouldn't equate to more living space for humans.

[Anonymous No.10732680]

>>10731811
>but still have gravity that’s about the same as Earth?
Sure, you just can't have as much metal in your core, lower the density.

[Anonymous No.10733103]

>>10732029
GIS software generally accounts for that sort of shit

[Anonymous No.10733688]

>>10733103
>
Any good ones?

[Anonymous No.10733727]

>>10731811
yes

[Anonymous No.10733810]

>>10731811
Keep density constant and increase rotation.

[Anonymous No.10733814]

>>10731841
build up

[Anonymous No.10733859]

>>10732029
Guess it'd be a small difference since elevation differences are tiny on landmass scales.
>>10731811
g=GM/r^2
Choose r larger than earth's, g equal to earth gravity and then put the M you get inside r.
Probably something awful will happen like your planet has to be all hydrogen and doesn't have a solid surface anymore.
Without doing weird fractals you'll get max surface area with a hollow sphere. And since mass increases the same as area (r^2) there's no limit to the size of a hollow planet with 1 surface g.

[Anonymous No.10735100]

>>10733814
How high up could you build?

[Anonymous No.10735106]

Make your oceans smaller but deeper so they hold the same volume but give more area over to land masses.

[Anonymous No.10735113]

>>10731811
Yes, if there is extremely variable topography and the planet was inhabited by goatmen

[Anonymous No.10735212]

>>10731969
this

[Anonymous No.10736744]

>>10735113
Goatmen?

[Anonymous No.10736995]

>>10732029
Check out coastline paradox.

[Anonymous No.10737065]

>>10731819
But couldn't you get a rocky planet that formed in a similar way to Earth's moon -- by knocking off a chunk of a larger planet's outer surface?

If so, you could get an Earth-sized planet without the denser iron core -- just silicate rock an shit all the way down.

That would have at least a little less gravity than Earth would.

[Anonymous No.10737066]

>>10737065
Oops, mis-internalized what OP asked. But you could similarly get a planet that was at least a little larger than Earth with 1g at the surface.

[Anonymous No.10737165]

>>10737066
>But you could similarly get a planet that was at least a little larger than Earth with 1g at the surface.
Probably quite a bit larger.
As an extreme example: a planet with 1g surface gravity and the same density as Titan, would have 2.9 times the radius of Earth and 8.6 times the surface area.

[Anonymous No.10737370]

>>10732042
I think bro meant it would be easier if you had a larger, less dense planet so the whole mass remains the same

[Anonymous No.10738912]

>>10737370
How would that work while still supporting life?

[Anonymous No.10740181]

>>10738912
Anyone?

[Anonymous No.10740189]

Much less dense core?

[Anonymous No.10741638]

>>10740189
Wouldn't that affect the magnetic field, though?

[Anonymous No.10741773]

>>10731811
Mass and gravity are linked

[Anonymous No.10742418]

>>10731841
geological records show continents are right now placed almost perfectly, for more habitable area we would need to lower average temperatures, a new ice age would do this, but right now we go in the wrong direction

[Anonymous No.10742425]

It would have to be some kind of crazy low density, or perhaps some alien civilization's megascale project of a hollowed out planet, but not normally, I'm not sure what exactly you mean by "significantly greater surface are". Jupiter sized? Uranus? Smaller? Jupiter or Uranus sized, probably couldn't get the same gravity unless hollowed, and there is some speculation that rocky planet;s can;t even get Jupiter sized.

25

Estimates vary, but I'll be cautious and say that a radius of roughly two Earth radii is most likely the upper limit for rocky planets.

There are many studies, both theoretical and empirical, that have tried to attack the problem. I'll attempt to summarize the results of a few of them:

Lammer et al. 2014: This group focused on planets losing their "hydrogen envelopes" - gaseous layers of hydrogen that they may accrete during the early parts of their lives. Their calculations indicate that planets of less than one Earth mass (M⊕) would accumulate envelopes of masses between 2.5×1016 and 1.5×1023 kilograms. The latter is about one-tenth of Earth's mass. Planets with masses between 2M⊕ and 5M⊕ could accumulate envelopes with masses between 7.5×1020 and 1.5×1028 kilograms - substantially more massive than Earth! This is the peak envelope mass, though; the group calculated that planets with masses of less than 1M⊕ would lose their envelopes within about 100 million years. They found that planets with masses greater than 2M⊕ will keep their envelopes, and so become "gas dwarfs" or "mini-Neptunes."
Lopez & Fortney 2013: Lopez and Fortney worked off of data from Kepler and modeled the radii of planets. They determined that planets with radii of less than 1.5R⊕ will become super-Earths, and planets with radii of greater than 2⊕ will become mini-Neptunes. That suggests a radius limit of 2R⊕, though most terrestrial planets will probably be under 1.5R⊕.

[Anonymous No.10743681]

>>10742418
Wrong direction?

[Anonymous No.10743758]

>>10731811
Naturally speaking, yeah, but there's a limit.
You could potentially build a huge-ass layered planet around a black hole and still have Earth-like surface gravity, too.

[Anonymous No.10743860]

Neptune has 15x the surface area of earth but only has ~113% gravitational force. Also similar is Uranus which is similarly large but 90% gravity of earth.

[Anonymous No.10743907]

>>10732012
someone please extrapolate this to the next logical step

[Anonymous No.10744533]

>>10743860
Could we somehow survive on a gas giant?

[Anonymous No.10744721]

>>10743681
You may have heard our planet is heating up.

[Anonymous No.10744723]

>>10743860
>Also similar is Uranus which is similarly large
Excuse me?

[Anonymous No.10744727]

>>10744533
You could make a network of floating islands, but you're still fucked as far as solar radiation is concerned. Too far out. Venus would be an interesting testing ground for such tech though, might be good for exoplanets and what not.

[Anonymous No.10746428]

>>10744727
What about a theoretical gas giant in the habitable zone of another star?

[Anonymous No.10746464]

>>10742418
What about during Pangaea where most of the land area was around the equator. Right now most of the land is tied up in tundra, buried under miles of snow and ice like in Antarctica, or desert and steppe regions

[Anonymous No.10746472]

>>10743907
>someone please extrapolate this to the next logical step
add wrinkles in the 4th dimension.

[Anonymous No.10746476]

>>10743907
fractal wrinkling
brain surface area approaches infinity
volume approaches zero

[Anonymous No.10746480]

>>10746464
Literally 70% of the landmass was a desert during pangaea.
Super continents are very bad for organisms because bodies of water are necessary to act as temperature regulators for landmasses. Landmasses need to be split up or their temperature variance becomes immense

[Anonymous No.10746503]

>>10746472
>>10746476
Ah fuck, these answers merged together in my mind. The omniperpetual growth rate of my ensuing intelligence explosion is literally not my fault.

[Anonymous No.10747100]

>>10731811
Yes. A lower-density planet. A significant amount of the Earth's core is iron-nickel. A more silicate-aluminum-titanium planet could exist that is larger.
Also, the rotation of the planet could be greater thus counteracting the gravity. This of course would vary by the sine of the latitude, meaning you'd feel the full effect of the gravity at the poles.

[Anonymous No.10747225]

>>10744721
No, I hadn't, tell me more

[Anonymous No.10748920]

>>10747225
Seconded.

[Anonymous No.10748946]

If it's hollow

[Anonymous No.10748991]

>>10748946
>theory

[Anonymous No.10749019]

>>10735100
As high as material strengths and engineering will allow.

[Anonymous No.10749138]

If we remove the iron core and replace it with more mantle, a planet can have 1.77 the area of earth. But if you don't need rocks you can go with a pure water world, with some floating shit to live on. Miles of water with a ice core, it would give you a surface area a massive 16 times the area of earth but with the same gravity.

[Anonymous No.10749892]

>>10746428
There are meant to be gas giants within that zone of a lot of stars (wasn't it recently argued that it looks like it's more common than rocky inner planets?) and I cannot think of a reason why a cloud base couldn't potentially work so long as the habitats were able to be buoyant at the right level and move around the planet at the right speed for good levels of gravity and radiation and all that good stuff. You'd be able to mine the gas giant for resources too.

Also comparing surface area isn't the best comparison as the gas giant surface would be built to be habitable by humans, no massive oceans or deserts. Neptune has ~120 times the area of the habitable parts of Earth. If we are going to stabilise in population around 10B, a Neptune in the habitable zone could support 1.2 trillion.

[Anonymous No.10750769]

>>10748946
Do people actually believe this?

[Anonymous No.10750888]

>>10746480
Not to mention the ridiculous weather

[Anonymous No.10750916]

Idiots, this is /sci/, all planets have infinite areas

[Anonymous No.10751028]

>>10750916
BT paradox: one sphere is equal to two spheres
>but it's not a paradox weh weh weh

[Anonymous No.10752713]

>>10751028
What is the definition of a paradox?

[Anonymous No.10753220]

>>10752713
The sphere in Banach-Tarski has a PhD in psychology, which is why it's okay to tear it apart and why two of it are a paradox.

[Anonymous No.10754593]

>>10753220
PhD? What?

[Anonymous No.10756060]

>>10753220
You lost me.

[Anonymous No.10757392]

>>10756060
Hello?

[Anonymous No.10758550]

>>10757392
Anyone?

[Anonymous No.10760156]

>>10758550
Hello?

[Anonymous No.10761628]

>>10731811
Cool picture

[Anonymous No.10762745]

>>10761628
Thanks

[Anonymous No.10763960]

>>10753220
I don’t understand

[Anonymous No.10764075]

>>10731811
Yes, if you build it yourself and it's not a real planet.

Advanced nanotechnology, robotics and AI systems could mine comets and asteroids and reassemble them into space stations with habitable surface areas many times that of Earth.
They could be planet-shaped if you want.

[Anonymous No.10764086]

>>10747100
Could a silicate-aluminum-titanium planet like that still produce a magnetic field like Earth's and shield us from its star's radiation?

Not really a habitable planet if we all get cancer and die

[Anonymous No.10764092]

>>10731969
Of all the possible celebrities, why did the French or Canadian kid think of Oprah?

[Anonymous No.10764266]

>>10764075
You'd need the materials what don't exist yet to do that.

[Anonymous No.10764964]

>>10764266
Explain? What materials, exactly?

The nanomachines, assemblers and AI-controlled construction systems don't exist yet either...

[Anonymous No.10765348]

>>10750769
yeah, they are stupid round earther

[Anonymous No.10767324]

>>10764964
Let's invent them, then!

[Anonymous No.10767616]

>>10731811
If it all comes down to heat and density, yes.

[Anonymous No.10767830]

>>10731811
Mars has almost the same land area as Earth with only a third of the gravity, because most of Earth is ocean.

[Anonymous No.10767854]

>>10747100
>rotation of the planet
>counteracting the gravity
You're full blown retarded, huh?

[Anonymous No.10767864]

>>10767830
Surely that can't be the reason. Even all water bodies on Earth must me only a tiny fraction of the planet's total mass, no?

[Anonymous No.10767885]

>>10767864
Well yea, the difference in gravity is because Earth is much larger in diameter than Mars.
My point was that despite being smaller than Earth, the dry land area of Mars is about the same because 70% of Earth's surface is underwater.

I assume when OP says "surface area" he means total water and land surface, but I thought the fact was worth mentioning.

[Anonymous No.10768015]

>>10732029
It's a very insignificant effect.
People really overestimate the steepness of slopes. 30 degrees doesn't sound that steep, but it's actually an uncommonly steep slope even in very hilly areas. I live in New Zealand (a very hilly country), and 30 degrees is pretty much the limit except near roads and the coastline.

[Anonymous No.10769633]

>>10768015
Thanks for sharing,

[Anonymous No.10770475]

>>10767854
No, but apparently you are, and like to express it.

[Anonymous No.10770483]

>>10737065
Possibly but everyone would die from radiation. Iron core is required for fields to protect us.

[Anonymous No.10771726]

>>10770483
Yeah unless you somehow have another way to produce one...

[Anonymous No.10773697]

>>10771726
Any ideas, there?

[Anonymous No.10774880]

>>10773697
Anyone?

[Anonymous No.10775447]

It's called being less dense than Earth.

[Anonymous No.10776196]

The Ringworld is about one million miles (1.6 million km) wide and approximately the diameter of Earth's orbit (which makes it about 600 million miles or 950 million km in circumference), encircling a sunlike star. It rotates to provide artificial gravity 99.2% as strong as Earth's fromcentrifugal force. The Ringworld has a habitable, flat inner surface (equivalent in area to approximately three million Earths), a breathable atmosphere and a temperature optimal for humans. Night is provided by an inner ring of shadow squares which are connected to each other by thin, ultra-strong wire.

[Anonymous No.10777638]

>>10731841
Unironically current Mars, already has similar land area as earth thanks to no oceans. If the planet would actually be earth sized for the gravity, bingo