Ultimate space simulation software

senuaafo
Astronaut
Posts: 59
Joined: 21 Aug 2018 14:47

### Re: Science and Astronomy Questions

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?

midtskogen
Star Engineer
Posts: 1487
Joined: 11 Dec 2016 12:57
Location: Oslo, Norway
Contact:

### Re: Science and Astronomy Questions

55 Cancri e might be 7 g/cm³ thereabouts.
NIL DIFFICILE VOLENTI

Watsisname
Science Officer
Posts: 2256
Joined: 06 Sep 2016 02:33
Location: Bellingham, WA

### Re: Science and Astronomy Questions

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.

PlutonianEmpire
Pioneer
Posts: 525
Joined: 02 Nov 2016 18:13
Location: Planet Meabh
Contact:

### Re: Science and Astronomy Questions

I am spontaneously teleported to the surface of Venus. How do I die, in excruciating detail?
Specs: Dell Inspiron 5547 (Laptop); 8 gigabytes of RAM; Processor: Intel® Core™ i5-4210U CPU @ 1.70GHz (4 CPUs), ~2.4GHz; Operating System: Windows 7 Home Premium 64-bit; Graphics: Intel® HD Graphics 4400 (That's all there is )

longname
Pioneer
Posts: 354
Joined: 13 Apr 2017 07:20
Location: ∞/The Multiverse/The Universe/Local Cluster/The Milky Way/Orion Arm/Sol System/Earth-Moon/Earth/UK

### Re: Science and Astronomy Questions

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?
[dah<500,26>dah<180,14>dah<180,21>dah<500,19>dah<180,26>dah<500,21>]

midtskogen
Star Engineer
Posts: 1487
Joined: 11 Dec 2016 12:57
Location: Oslo, Norway
Contact:

### Re: Science and Astronomy Questions

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].
NIL DIFFICILE VOLENTI

Salvo
Pioneer
Posts: 428
Joined: 03 Nov 2016 07:19
Location: Veneto, Italy
Contact:

### Re: Science and Astronomy Questions

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.
The universe is not required to be in perfect harmony with human ambition.

CPU: Intel Core i7 4770 GPU: Sapphire Radeon RX 570 RAM: 8 GBs

PropsValroa
Observer
Posts: 3
Joined: 12 Oct 2022 15:31

### Re: Science and Astronomy Questions

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.
"I don't understand faith. I only understand power." - Brye Chandler

jjliang
Space Tourist
Posts: 37
Joined: 19 May 2021 07:51

### Re: Science and Astronomy Questions

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...

midtskogen
Star Engineer
Posts: 1487
Joined: 11 Dec 2016 12:57
Location: Oslo, Norway
Contact:

### Re: Science and Astronomy Questions

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.
NIL DIFFICILE VOLENTI

A-L-E-X
Galaxy Architect
Posts: 3354
Joined: 06 Mar 2017 20:19

### Re: Science and Astronomy Questions

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.