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senuaafo
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Re: Science and Astronomy Questions

31 Aug 2022 03:15

What is the maximum realistic average density of a rocky planet?
I know Earth is around 5.5 g/cm^3 and is one of the densest in our solar system, but
 can they realistically get even heavier, I'm thinking in the 7 to 8 g/cm range?
 
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midtskogen
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Re: Science and Astronomy Questions

01 Sep 2022 04:36

55 Cancri e might be 7 g/cm³ thereabouts.
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Watsisname
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Re: Science and Astronomy Questions

04 Sep 2022 11:22

A density as high as 7 g/cm^3 is plausible for a mostly silicate "rocky" planet, with a mass of around 10 Earths. For a given bulk composition the density will also be greater if the planet's mass is greater, due to compression. This effect becomes very significant for masses more than about 100 Earths. Theoretically for planets above about 1000 Earths, their sizes should decrease as their masses increase, causing the density to really skyrocket. (This is due to electron degeneracy, and white dwarfs and neutron stars work the same way.) Though of course such massive terrestrial planets are probably not realistic.

Back to something more sane such as 10 Earth masses, if we allow more of the planet to be made up of iron, then the maximum density can be well over 10 or even 15 g/cm^3.  See earlier post here for more detail using the mass-radius relation for solid planets, though in that post it was for understanding the lowest plausible densities. :)
 
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PlutonianEmpire
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Re: Science and Astronomy Questions

04 Oct 2022 08:25

I am spontaneously teleported to the surface of Venus. How do I die, in excruciating detail?
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Re: Science and Astronomy Questions

04 Oct 2022 15:38

I am spontaneously teleported to the surface of Venus. How do I die, in excruciating detail?
How much detail can there be in an instant death?
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midtskogen
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Re: Science and Astronomy Questions

09 Oct 2022 23:59

I am spontaneously teleported to the surface of Venus. How do I die, in excruciating detail?
Your death would be pretty similar to being teleported into the ocean at 950 m depth.  Your death is instant and your body will be crushed by the pressure.  Then, within the next few hours you will be baked dry but not burn.

If you were teleported high up in the atmosphere where the pressure is equal to that of your origin, however, you would not feel that much immediate change except that the little sulfuric acid in the air would sting your eyes and lungs, and you would pass out and die within a few minutes from breathing air almost entirely made up from CO[sub]2[/sub].
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Salvo
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Re: Science and Astronomy Questions

12 Oct 2022 06:23

The sad thing about this is that Earth will be exactly like Venus in the future, and probably even hotter, because of runaway greenhouse effect...
This is so sad to think about. Everything we created in these years, even the most durable thing in the most quiet place of the world will be erased.
Last edited by Salvo on 13 Oct 2022 04:15, edited 1 time in total.
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PropsValroa
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Re: Science and Astronomy Questions

12 Oct 2022 15:37

I have a question, hypothetically speaking if a M9 Red Dwarf Star was in the oort cloud, would it be visible from Earth? What is the upper mass / spectral category a star can have in the oort cloud, without it being visible from the Earth? Just asking for a worldbuilding project.
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jjliang
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Re: Science and Astronomy Questions

12 Oct 2022 19:44

It's pretty much a shame that only microbial life will be able to survive a timescale up to a billion years before Earth finally gets sterilized by a runaway greenhouse effect. Humans are all but a mere blip in geologic time. Who knows how many times complex life elsewhere have came and went within a very short period of time, while the microbes on their planets carry on. Perhaps one day, all that's left of our civilization, species, and even our planet, but especially our endeavor will be the various unmanned interstellar probes we have already sent off into space. Better visit certain places here on Earth sooner than later, and enjoy the planet's present day conditions while they still last, while we still can. We are like a baby born to impossibly old parents...
 
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midtskogen
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Re: Science and Astronomy Questions

13 Oct 2022 05:04

The sad thing about this is that Earth will be exactly like Venus in the future, and probably even hotter, because of runaway greenhouse effect...
This is so sad to think about. Everything we created in these years, even the most durable thing in the most quiet place of the world will be erased.
It's a billion years in the future.  Even if the sun continued doing what it does now, and Earth's interior continued its business, nothing that we create will last a billion years.  Most rocks you'll find are younger than a billion years.  Even in a million years everything created will be lost unless recreated many times over.
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A-L-E-X
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Re: Science and Astronomy Questions

03 Dec 2022 18:42

The sad thing about this is that Earth will be exactly like Venus in the future, and probably even hotter, because of runaway greenhouse effect...
This is so sad to think about. Everything we created in these years, even the most durable thing in the most quiet place of the world will be erased.
It's a billion years in the future.  Even if the sun continued doing what it does now, and Earth's interior continued its business, nothing that we create will last a billion years.  Most rocks you'll find are younger than a billion years.  Even in a million years everything created will be lost unless recreated many times over.
Forget billion years, in a million years we'd better have colonized the galaxy or we'll be extinct.

And what about for a planet made entirely of diamonds, Wat?

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