I've seen references a handful of times to the fact that a toroidal world is theoretically possible but realistically won't form naturally. That gives me some thought: What objects are possible, but wouldn't naturally exist? Something that, if we came across it, we'd be able to immediately go "Someone built that."

To be complete, I am excluding megastructures such as Dyson Spheres, Ringworlds, and the like. I want weird things, like a planet set up in an orbit that's too "Perfect" or the above torodial world. To be more complete, the objects in question should be easily identifiable as artificial by simply existing, not by what's on them

Additionally I am similarly excluding the how of the object. Putting the planet together, or moving stars to a specific orbit, is not in the scope of this question. Presume that whoever built it had an unlimited budget of time, energy, and resources.

Further Clarification: Said object must be easily visible from the edge of the system. Assume that the object is being detected by a ship just entering the system via a hyperlane or grav point or some similar specific-natural-point to specific-natural-point FTL system.

I am looking for the most unquestionably artificial object that can scientifically exist. Something that one look from a star system's width away makes you go "Someone made that." The object shouldn't be larger than a planet and should be made of "natural" objects - No refined metals or other things. There also shouldn't be any scanning or exploration required to determine its nature.


closed as primarily opinion-based by Mołot, Vincent, Aify, L.Dutch, Mormacil Jul 1 '17 at 15:53

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ It's not possible to guess how wound you rate answers now. For example how would you rate celestial teapot vs hollow rock with atmosphere vs torus planet?.. $\endgroup$ – Mołot Jun 30 '17 at 23:32
  • $\begingroup$ It was a bit too vauge. Added some clarifications. $\endgroup$ – Andon Jul 1 '17 at 1:24
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    $\begingroup$ You are asking for a list; this question is therefore too broad and opinion based. WB.SE is not a brainstorming type site, and these types of questions do not fit the format of SE in general. $\endgroup$ – Aify Jul 1 '17 at 4:03
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    $\begingroup$ Roughly speaking, any shape that does not look like an ellipsoid or like a ring will be unnatural. I'm not really sure what you are trying to get at in the question ... The answer could also be in terms of really weird orbits for three body systems ... $\endgroup$ – cutculus Jul 1 '17 at 5:08
  • $\begingroup$ What about a binary system where one of the stars is made from antimatter? It is stable as long as they don't intrude into each others Roche lobe, but radiates detectably from the area where their stellar winds meet. $\endgroup$ – b.Lorenz Jul 1 '17 at 9:23

Terry Pratchett's dark side of the sun has several, they are called joker artifacts and are the leftover signatures of a precursor races. examples include, a stable ring of mutually orbiting stars, a protostar with inside out planet inside it, a neutron star core that has had tunnels cut through it creating a gravity maze, and the planet Band described thusly.

"Band spins on its axis so fast that the equator has a noticeable bulge to it. It looks like a solid gas giant with a twenty-five thousand mile wide band of mountains at the equator, edged by two strips of of grassland which are edged by two strips of sea which end at the circles of ice on the poles."

It appears to be a planet sized wildlife preserve.

It also contains the First Sirian Bank a 7000 mile tidally locked asteroid composed of a combination metal impurities and fault lines to create a sentient supercomputer powered by the thermal gradient between the light and dark side.

The trick is to think of something that is technically possible but just so extremely unlikely it could never happen naturally. Like planet surrounded by moons make of regular geometric solids or a planetary system where each planet is identical.


/I am looking for the most unquestionably artificial object that can scientifically exist. /

An artifact from an unfamiliar civilization might be mistaken for a natural phenomenon. The most unquestionable artificial object will be one which echoes the viewer's own civilization. The unmistakable thing viewed should be a reproduction of a familiar artificial thing: an artifact from the viewer's own civilization. For example, Michaelangelo's David. Or the Statue of Liberty. The viewer will immediately recognize the object and understand that such a thing would not come into existence naturally. What is viewed is a copy of the thing, which must have been made by an intelligence copying it on purpose.

This is the method used by the aliens in the Jodie Foster movie Contact.

  • $\begingroup$ Good point. Only afterwards the natural origin might be explainable. Of course you cannot proof that it is impossible to exist naturally $\endgroup$ – Henning M. Jul 1 '17 at 8:46
  • $\begingroup$ Those wouldn't be visible from the edge of a star system. $\endgroup$ – Bellerophon Jul 1 '17 at 12:30
  • $\begingroup$ @Bellerophon - I should have mentioned that the replica in question is not a scale model of David, as you might place in your tasteful rotunda. This is Big Ass David, capable of kicking the Death Star like a soccer ball. $\endgroup$ – Willk Jul 1 '17 at 13:21

A solar system showing an "ordered complexity" in the arrangement of orbiting bodies would be a good candidate in my opinion. For instance one that exhibit a highly peculiar gravitational landscape such as structured distribution of Lagrange points, or patterns in asteroid belts.


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