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Imagine that we start expanding the International Space Station until it becomes a ring encircling the whole Earth. Then we started widening the ring until it met at both poles, forming an orbital eggshell around the entire planet.

Ignoring all the problems, like that it's starving the planet's surface for sunlight. What would you call this kind of enormous space station?

HDE 226868
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Henry Taylor
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9 Answers9

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A Dyson Sphere is meant to capture radiation and convert it to usable energy. Since an earth-like planet only reflects light back, that point would be moot. In any case, here's some suggestions:

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OnoSendai
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Well a Dyson Sphere is named after the person who popularised the idea and also the shape of the object itself.

Without paying homage to a person or entity, it makes sense to call it after its function. Around a planet, there's a few functions it could have which allow you to derive a name for it.

  1. Defence: A megastructure created with the intent of protecting the planet. Names such as Fortress Sphere or simply "Defence layer" depending on how many layers the structure has (I mean, why stop at one sphere right!?). Dropping references to famously impenetrable things also works, like Knox Sphere.
  2. Imprisonment: In this case, the planetary inhabitants are most likely going to be miffed with it, so they won't refer to it by it's technical name (Uhh.. Interstellar Movement Restriction Construct?) and call it something like the "Cage" or "Iron Curtain" (Stalin in Spaaaaace)
  3. Habitation: Suppose the sphere could create an atmosphere usable by humans, turning Jupiter's weather conditions into exactly like that of Earth's. Names like "Biosphere" or "Environment Simulating Orbital Structure" (ESOS, BOOOM, all aboard the sci-fi acronym train!).
  4. Salvation: Suppose the planet died, so the people built the structure to live on once the planet collapsed, or like Coruscant in Star Wars, they just built so much that eventually it took over the entire planet, inadvertently forming a sphere. In this sense, biblical names work well like "The Orb of Eden" or "The layer of Jannah".

Another way of looking at this, if the orb has an atmosphere of its own, it's plausible that no one is even aware that there is a planet inside the sphere. This would make an excellent set piece, where the name would simply be whatever the Planet was called.

What I'm saying is: There is no widely accepted term for it. Go and be the person to make it!

Brythan
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SamBC
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There is no name for the sphere version. The ring version is an Orbital Ring.

You could most likely use the term "Planetary Dyson Sphere" or if it is defensive in nature "Planetary Shield". I've also heard the term "shell" used to describe structures similar to what you are asking about.

Be aware though that it is a structure with no real value and yet incredibly expensive to build. Orbital rings are very useful but a full sphere not so much.

Tim B
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    Don't forget that they are dynamically unstable too. It'll require active controls to keep it from striking the planet. – Jim2B Feb 02 '16 at 19:09
  • I'm assuming you'd support it on either towers or tethers, but yes you are correct that stabilization of some kind would be required. – Tim B Feb 02 '16 at 19:12
  • No real value? Suppose you put one around the moon (making parts of it transparent), and then put an atmosphere inside it? Would you not have created a habitable world? 9.3 billion acres of it. (I use acres 'cause that's what US real estate prices are quoted in.) – jamesqf Feb 02 '16 at 21:52
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    @jamesqf Or use a fraction of the mass to create thousands of Orbitals (https://en.wikipedia.org/wiki/Orbital_(The_Culture)) and get far more land-for-mass. Using mass to create gravity is very inefficient. – Tim B Feb 02 '16 at 22:10
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    @jamesqf wouldn't the friction against the air very quickly lead to the shell stopping rotating and becoming even more unstable than it already is – Richard Tingle Feb 02 '16 at 22:24
  • @Tim B: Orbital habits, besides being claustrophobic places to live, are too small to maintain viable ecosystems over the long-term. You need a planet for that, at least on available evidence :-) Nor would the mass necessarily be that great, if it's just a thin film (or several layers for redundancy) of say nanoengineered graphene. And it would be tethered to the surface. For the moon, you might start with the idea of roofing craters with inflatable domes, and keep on going. – jamesqf Feb 03 '16 at 06:04
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    Read up on orbitals before you say that they are small ... – Tim B Feb 03 '16 at 07:08
  • @jamesqf Yeah, no. Tim isn't talking about IIS-like "habitats". More like Ringworld :) You get far more bang for your buck than with a full sphere, and it's much more viable engineering anyway. A ring will give you easy gravity and massive amounts of habitable land area. If you took the material needed to build a solid shell around the Earth and made it into ringworlds, you'd get much more surface area to work with, and without having to deal with a lot of very expensive issues. – Luaan Feb 03 '16 at 09:13
  • Yeah, orbitals are a step in between ringworlds and habitats. They orbit the sun like a planet but with a 3.7 million km diameter. This gives you earthlike day-night cycles and simulated gravity. The orbit is just as stable as that for a planet but you use a fraction of the mass for the living area. – Tim B Feb 03 '16 at 09:25
  • @Tim B: The problem with orbitals is that you need a handy supply of unobtanium to build one :-) The O'Neill-style habitats that could be built with available materials are claustrophobic and probably unsustainable. – jamesqf Feb 03 '16 at 20:00
  • "There is no name for the sphere version" - there is, in astroengineering circles it's called a supramundane world (or shell). – Radovan Garabík Feb 04 '16 at 12:58
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    If a ring is an orbital ring, it would seem to make sense to call it an orbital sphere. – DCShannon Feb 04 '16 at 17:26
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You could call it a roof. Or perhaps an armilla?

If you were going to get all hard SF about it, a rigid shell around a planet (or indeed around a star) wouldn't be stable, and would indeed fall onto the planet unless it was perfectly centered on the planet's center of mass as @RichardTingle suggests. If it were as low as the ISS, I doubt it could last a week without some kind of (huge) thrusters to keep it in place.

A ring is OK because each part of the ring is in orbit. But as you start to widen the ring, the edges are not in orbit-- they're moving too slowly and in the wrong direction for their altitude, which means they're pulling on the rest of the ring, and it would be nearly impossible to balance those forces.

However, an airtight sphere could be supported by air pressure, and have tethers/struts connecting it to the planet. Those wouldn't have to support the weight, they'd just be to stop it drifting around. Could be a good source of cover artwork...

bobtato
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The specific instance of the construction, built around Earth specifically? I wouldn't be at all surprised if it were referred to as The Firmament.

The general construct I might refer to as a hoover bag, if I were feeling flippant.

sh1
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It would be called "Weird Transit Feature" ...by aliens! Its purpose is to make Earth both more easily visible and more intriguing for alien civilizations who search for other planets using the transit method.

Earth will become more visible when transiting the Sun, because its larger radius would produce better noticeable transits. Also, the transits would be more interesting because mass/radius/density/gravity calculations performed by the aliens will show that this planet is something very unusual, deserving more detailed investigations.

So it is it. We just need to build this thing and then wait to be visited by our interstellar tourists!

Victor Stafusa - BozoNaCadeia
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  • or, its already present with a map of the universe projected onto it so we can be kept bottled away from the rest of the peaceful galactic civilisations... ever wondered why we've not found any other life, or why we need "dark matter" to make our observable cosmology physics calculations work... hmm... hmm... – gbjbaanb Feb 04 '16 at 08:43
  • Just did the maths and increasing the earth's radius to the ISS orbit consitutes a 6.2% increase, which might not be noticably different to our alien observers. – Max Williams Feb 04 '16 at 16:05
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Supramundane shell or supramundane world is the established term, a concept introduced by Paul Birch, originally in his article "Supramundane Planets", Journal of the British Interplanetary Society, 44, 169 (1991) [PDF].

The term is derived from the Latin supra "above" and English mundane "of, relating to, or characteristic of the world", which was in turn derived from Latin mundus "world".

Radovan Garabík
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    Can you expand your answer? It's currently just a link with a word meaning "beyond uninteresting". – Samuel Feb 02 '16 at 20:09
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    It's the other definition of mundane, meaning earth. – Ax. Feb 02 '16 at 21:03
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    @Samuel What is there to expand? The strudture is called a "supramundane world", or "shell" if it does not quite deserve to be called a world. – Radovan Garabík Feb 02 '16 at 21:05
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    @RadovanGarabík Consider how useful your answer would be if the link goes dead. I'm suggesting you put the salient information from the link into your post to avoid making it totally useless in that eventuality. – Samuel Feb 02 '16 at 21:10
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    The first link is already dead (gives me "An internal server error occurred. Please try again later."). Please don't post link-only answers. See also "Are answers that just contain links elsewhere really “good answers”?" on stackexchange meta. – Philipp Feb 04 '16 at 08:35
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    @Philipp Well, the OP asked how is the structure called - the established name is "supramundane world". I kind of do not get why the other answers to clearly terminological question either try to create a novel term out of blue sky, or dive into technical and scientific issues, where the question is plain and simple asking about a name. BTW Orion's Arm page works well again (it's quite stable, long time existing site) – Radovan Garabík Feb 04 '16 at 12:54
  • @RadovanGarabík You could at least try to explain what "supramundane" means and why it's called that way. – Philipp Feb 04 '16 at 13:00
  • @Philipp Well, the author of the idea called it that way :-) I did not want to bring forward the etymology, because I'd be just guessing anyway (supra=above, mundane=of this world), and the Latin origins of mundane are kind of not relevant. – Radovan Garabík Feb 04 '16 at 13:04
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    With the edit, this is the only correct answer. Hopefully it gets chosen. – JackArbiter Feb 04 '16 at 22:53
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The closest thing I could find is the Globus Cassus. It is a mega-structure around the planet Earth, but it eventually uses up all the matter of the earth.

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ThomasW
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It's called a Shell World. What you're describing isn't exactly like what's referred to in this article, but I think it close enough to serve your purposes, and it might give you some ideas.

https://www.space.com/23082-shell-worlds-planet-terraforming-technology-infographic.html

Len
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