How much play is there in building bigger-than-Earth planets that support humans?
Are there models, problems, and or engines for building life-sustaining worlds?
I believe that my approach is backwards. I have written a lot on my world and have been slowly working at making the humanoids, animals, plants and scale of the world all work.
This is the main question presently:
What would the makeup of a world need to be, to be 46.7 times the size of Earth, with 14% less gravity?
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1 answer
Not much.
I assume that by "14% less gravity" you mean that at the surface, the force of gravity is only 0.86 times its strength on Earth's surface, i.e $g=0.86g_{\oplus}$. You also say that the size is 46.7 times the size of Earth, or $V=46.7V_{\oplus}$. Putting these requirements together tells us that the planet's mass and radius must be $M=11.2M_{\oplus}$ and $R=3.6R_{\oplus}$. The density is therefore $0.239$ times that of Earth - that is, $1.32\text{ g cm}^{-3}$.
Looking at various mass-radius relation models, the planet should be composed largely of water, with a significant hydrogen/helium envelope. It's not significantly different from Uranus of Neptune in size, mass and density.
Such a planet will certainly be gaseous - it is far too big to be a super-Earth, although it could be a massive solid planet - because of how massive it is. It will likely have scooped up a fair amount of gas and dust from the original protoplanetary disk.
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