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Could a gold shell around a planet exist, suspended by a magnetic field (gold is diamagnetic), given the following constraints?

  • A gold layer enveloping a planet, arbitrarily thin.
  • Unspecified height, likely to be where atmosphere is less dense with fewer jumps of pressure.
  • a strong magnetic field that repels the gold and keeps it suspended thanks to gold's diamagnetic properties exists or was created.
  • No specific function has to be performed by the sphere, just aesthetics. Make the planet shiny as a gold ball.
  • An alien race has sufficient energy reserves (e.g. huge uranium deposits) to avoid relying on solar panels. They prefer being shiny instead of using solar power.
  • The sphere should not be built, it just needs to be kept suspended ( so I do not need to know how it was built, that's another problem, just need to know if it can be maintained)
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    $\begingroup$ Dyson spheres aren't planets, so this question is very confusing. $\endgroup$
    – rek
    Commented May 14, 2020 at 23:41
  • $\begingroup$ If the residents of the planet were very, very shy, or excessively paranoid about privacy, they might want to cover their entire planet with a thin opaque film that not even radar could penetrate. $\endgroup$
    – Justin Thyme the Second
    Commented May 15, 2020 at 0:06
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    $\begingroup$ dyson spheres cover suns $\endgroup$
    – Topcode
    Commented May 15, 2020 at 0:12
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    $\begingroup$ Wouldn't a dyson sphere around a planet with an atmosphere be held up simply by air pressure, like a huge balloon around the planet? I could see using the diamagnetic property to BUILD the sphere, using it to hold the sections in place until they formed the continuous skin of the balloon. I can, however, see a complication with particles, solar wind, solar flares, ionization, magnetic fields, conductive gold foil, induction, eddy currents, chaotic fields, and diamagnetic properties. A huge Van de Graaf generator sphere around the planet? Better than solar energy, a continuous lightning storm. $\endgroup$
    – Justin Thyme the Second
    Commented May 15, 2020 at 0:29
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    $\begingroup$ A plot twist - the pressure builds up, the balloon free-wheels around the earth, is punctured by Mount Everest, the air whooshes out of the hole, taking atmosphere with it, and the earth is set off course by Newton's Law. OOOOhh, interesting disaster scenario. $\endgroup$
    – Justin Thyme the Second
    Commented May 15, 2020 at 16:30

2 Answers 2

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Not likely, but maybe you could use dust?

First, as mentioned by @JustinThymetheSecond, the magnetic field around a planet is not static. Earth's magnetic field is pushed around constantly by the Sun, meaning anything that tries to be kept suspended by this field would quickly be pushed apart. A related issue is that as this foil is pushed around, large eddy currents will form - likely melting the foil.

Second, anything that reflects light will also be pushed by the "light pressure" - the same concept that is used for solar sails will ram any gold foil into your planet.

Third, unless you have openings in this gold foil, it will slowly inflate due to the planet off-gassing. Normally, a planet's atmosphere slowly boils away into space, being replenished by gases released from natural or other processes on the planet. This inflation will eventually rip the foil apart.

Cool idea, and you could maybe use gold dust, or some other "shiny" particle to get a similar effect - just note that it will need to be continually replenished. Particles would avoid most of these issues, but there will be a "trail" of particles both into the planet's atmosphere and streaming outward from the planet away from its sun. They will still block a lot of the incoming light, as well - depending on the concentration.

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  • $\begingroup$ Actually, I was thinking gold foil shreds, like chaff is used to mask radar signals. $\endgroup$
    – Justin Thyme the Second
    Commented May 15, 2020 at 3:18
  • $\begingroup$ @JustinThymetheSecond - chaff could work too, but if it’s a massive connected sheet, it’ll have problems. $\endgroup$
    – IronEagle
    Commented May 15, 2020 at 5:42
  • $\begingroup$ And loosely overlapped sheets without connections? $\endgroup$
    – CoffeDeveloper
    Commented May 15, 2020 at 8:01
  • $\begingroup$ It.s the fact that gold is extremely electrically conductive that is the problem - more conductive than copper, by far. The sheets would have to be electrically insulated from each other, so that an electric current could not flow throughout the entire surface. $\endgroup$
    – Justin Thyme the Second
    Commented May 15, 2020 at 12:58
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Freeman Dyson's theory was never talking about an actual sphere built around a star, but a swarm. encasing a star around a sphere is impossible with existing materials, so the best you can get is building a dyson swarm. I.E. a cloud of stations or panels enveloping the star.

the same can actually be done with planets, Albeit never as powerful as an actual dyson swarm given you can only harvest a billionth of the energy from the star.

we see such things in the Mobile-suit Gundam anime, albeit not what you are directly asking.

but as for making the swarm of panels look like a sphere, you can simply use orbital mechanics to orbit the plates. and enough of them would make the planet from a distance look like a gold sphere.

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