Ok, I noticed some very intelligent answers on this platform and I would love your input on the planet for my book trilogy. I have been working on the blueprint, story structure, and characters for years and I am ready to start writing the book format soon. The last thing I want to cover is to make the planet more 'believable'. Let's agree that it doesn't have to be correct. I just need it to be believable. Like we believe the Death Star in Star Wars or the Halo in Elysium or... Halo.

For my peace of mind I will try to explain without giving away to many details.

The planet would exist in a piece of dead space. It has to be unreachable and inescapable with no stars or planets anywhere nearby. (Because a large part of the galaxy around it has been destroyed a long time ago in order to create the base of this planet that should never be found).

Life on the planet should be possible. But like I said. There are no stars. Instead, I envision a big artificial moon with a big light source that would look like a prison searchlight directed at the planet. This light source should be designed to emit just the right amount of energy to enable life on the planet.

The planet should be inescapable. Even for lifeforms that can teleport or fly or build a space ship. I'm open to suggestions. Maybe by some kind of electromagnetic atmosphere or gravity that increases as you move further from the surface. (I know it works the other way around but like I said... I need to make it believable and I need al of the above to be possible for the sake of my story).

Finally, the core of the planet is used to imprison a huge entity. Between the surface and the core I would need another barrier that prevents something very powerful from breaking out of use its powers to influence the surface. The core should be reachable by human-sized tunnel systems though.

I left out a lot of context to guard my concepts, but I'm very exited to learn more about how this kind of artificial planet would be 'possible'.

Kind regards and thanks for your time and interest, Luke

  • $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Aug 19, 2022 at 10:13
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    $\begingroup$ Without diving into the other problematic details, an inhabitable planet without a star is far beyond the realm of 'believable' to me. You have no energy input at all. How do you even power your artificial moon/star? How would anyone have managed to create a planetery-scale structure away from everything, with no access to materials, energy, etc? You would, (for starters!) essentially need to have access to an incredibly compact and practically infinite energy source. That is a level of technology that is likely to break your universe because the things you could do with that are god-like $\endgroup$ Aug 19, 2022 at 10:44
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    $\begingroup$ To touch on the other aspect, a force that gets stronger the further you go implies an infinite amount of energy as well. To put it in more direct terms, what you are proposing, is to basically attract all of the universe to you. The furthest confines of the universe (stuff that are billions and billions of lightyears away from you) will be (in a few billion and billion of lightyears) somehow accelerated very close to the speed of light because the force exerted on them is incredibly high. On the bright side, something impossible to escape exists; black holes. Not the most peaceful shelter tho $\endgroup$ Aug 19, 2022 at 10:58
  • $\begingroup$ It really makes no sense that someone would destroy hundreds of billions of planets, stars, and other celestial bodies, somehow doing so thoroughly enough that nothing re-formed from the debris, in order to keep this one planet from being found. Not only would it be many, many times more difficult than just moving the planet into intergalactic space or finding one already there, it would actively attract attention to that area. $\endgroup$ Aug 19, 2022 at 15:07

2 Answers 2


Highly unimaginable

Really complicated situation with hard to believe parameters, I will try to presents a solution for each points you made and you will see the different solutions invalidate others...

  1. Dead part of the universe

Easy, Rogue Planets wandering in-between galaxies exist. Following a gravitational events in their system or stellar events.

  1. No stars BUT life possible

Ok, that's the first complicated part. To support life firstly you need chemistry (and so energy). Without stars you have to imagine the planet is big enough to have it's own core liquid (which will be cooling and so give energy) for enough time to create life. The best possibility for you would be a super earth (and if possible with it's own satelite to expand the time allowed to you core to stabilise. Indeed without the Moon, our core wouldn't have that much activity right now. The water (or someone could suppose ammonia) would have to be liquid to allow your lifeform (which is why we spoke about energy just before). Two solutions: really high atmospheric pressure or under a solid crust to be closer to the core.

  1. Unescapable

A super-earth should be enough (with the gravity). But most of all : why would they need to leave? If they are isolated on a rogue planet they couldn't reach anything else because they would be way too far away from anything. Let's suppose they still want to try, with the hypothesis I presented in 2) of a superearth. The energy needed would be exceptional for it. Secondly we suppose you have a really thick and high-pressurized atmosphere (for the sake of liquid on the surface). Even if they can escape the gravitational pull from the planet, the re-entry would be almost impossible beacuse of the atmosphere.

A superearth with twice the radius of Earth would need a bigger rocket than the Saturn V only for a satelite

  1. Entity-like core

Well, imo it's not possible with what I said about the core. And highly unbelivable to anyone reading it. A core reachable break the possibilty of having a liquid core and a super eath-like

  1. Light source

The idea of a moon lightning a planet is not feasable in my opinion. The amount of energy you would need is inimaginable to light a planet (which is a superearth in my supposition). And I would repeat myself but you can't bring fuel to this moon because you can't escape. Without fuel, where does this moon bring the energy to light an entire face of a planet for possibly million of years? Best solution; no light source from outside. Your species have their own (like in the deep sea on earth)

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    $\begingroup$ This thing is also supposed to be hidden. Domes or tunnels with internal light sources: hidden, the heat that leaks out could just be geothermal. Giant moon-spotlight: the planet is the only source of light for thousands of light years, and it has the spectrum of a sunlit life-bearing world. That moon would be a ~200 petawatt blinking light screaming "over here!". $\endgroup$ Aug 19, 2022 at 16:17
  1. Moon. Mooon size fusion plant. Possible, need source of hydrogen/deuter to make enough plasma and energy. Or if need work only for short time like 10000 years then only make this moon bigger - like Jupiter or so.

  2. Planet. Hollow. Long time not possible without level 2 civilisation technology and need level 2 civilisation energy source. Main problem - tidals from moon will destroy crust and collapse to core. To prevent escape. Make it rock without iron, silver, copper, lead, platinum and other rare metals and You are good. If have only silica and carbon on surface then no way to make any tools and escape planet.

Anyway. Level 1 civilisation - almost not possible to make it. Level 2 possibl but why? There are easiest ways to do most things. Destroy half of galaxy to make small prision - really?

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    $\begingroup$ I disagree with your assessment, particularly with your first point. A type II civilization is defined as able to harness all of the energy input from their star. What you are proposing is a civilization so adavanced that they can build a new star in the most isolated confines of the universe, away from everything. This is kinda the same difference there is between being able to use our weather to harness energy (which we do very poorly), or to completely define our weather. A type II civilization would look like mere monkeys compared to what you propose $\endgroup$ Aug 19, 2022 at 11:08
  • $\begingroup$ IIRC planet construction is K1.8 and star construction is K2.4 K2 is from one star up to almost galaxy energy level. It is wide range. $\endgroup$
    – Kamitergh
    Aug 19, 2022 at 11:23
  • $\begingroup$ I stand corrected, I didn;t know there were subdivisions. Tho I do the suppose that the implicit assumption behind the definition of the K2.4 star-building-level is that you have access to energy sources. Building it away from any active energy source is definitely a significantly more advanced challenge. $\endgroup$ Aug 19, 2022 at 11:28

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