A Dyson Laser would be a spherical swarm megastructure arrangement of robots focusing mirrors directing sunlight towards a particular planet in a system heating it with enough energy to melt it.

This is similar to a Dyson sphere or swarm.

Except the goal is not colonization, but rather to have aim-able mirrors on the interior with which to focus starlight on the planet to melt it.

Is this possible? If so, what are the limitations?

  • $\begingroup$ If it was spherical wouldn't it block the sunlight? I think any society capable of engineering such a thing could probably find simpler ways to melt a planet. $\endgroup$ Jan 11, 2015 at 7:45
  • $\begingroup$ @GrandmasterB The planet to be melted is inside the sphere. Mirrors on the inside of the sphere swarm. $\endgroup$ Jan 11, 2015 at 7:46
  • $\begingroup$ @GrandmasterB The star is also inside the sphere (in case you're unfamiliar with a Dyson Sphere/Swarm) en.wikipedia.org/wiki/Dyson_sphere $\endgroup$ Jan 11, 2015 at 7:50
  • $\begingroup$ Ok... but what is the purpose of doing this? Wouldn't it be simpler to pound a planet with redirected comets? $\endgroup$ Jan 11, 2015 at 8:14
  • $\begingroup$ @GrandmasterB Well, I'm not particularly looking for the simplest answer. And this would/could be a more instantaneous attack if there is FTL travel. A fleet of these drones could pour from a wormhole instead of making a long trek from a Kuiper Belt like area. $\endgroup$ Jan 11, 2015 at 8:20

1 Answer 1


Main issue with a dyson laser is that no one would actually use it.

Density of solar energy drops (duh) with the square of distance from the sun. This equals to the amount of hardware you need to build, deploy, and protect also increasing with the square of the distance. So if you want to do something with sunlight you always want to be on the inside not outside.

I think the hypothetical planet killers would build a fleet solar powered lasers large enough to hit a planet from interplanetary distance, deploy them inside the orbit of mercury, and then have fun shooting down anyone trying to destroy them. Lasers being quite a bit better at shooting spaceships or missiles than huge mirrors are. And much smaller targets.

So while a civilization capable of building a dyson sphere probably could build a dyson laser, they also easily could get the same effect with an order of magnitude lower use of resources and time.

And wasting an order of magnitude of your resources is not really feasible to do from the viewpoint of economics or politics. So I guess the answer would be no.

  • $\begingroup$ Then again, such a Dyson laser might be a viable way to heat up a planet to terraform it. Not the cheapest ways to do it, but hey, might be an additional feat of the Sphere. $\endgroup$ Feb 3, 2016 at 9:11
  • $\begingroup$ I'd prefer a Starkiller $\endgroup$ Mar 30, 2016 at 21:48
  • $\begingroup$ Theoretically, a full ellipsoid is not necessary. It could be a partial shell of the full ellipsoid. The target is positioned inside the virtual full ellipsoid at the far focal point. (The light source star is at the other focal point.) A partial ellipsoid reflector cupping around one star could focus much of its light. See math.ubc.ca/~cass/courses/m309-01a/dawson A catch is that stars are not point sources, so the cup would have to be many AU across to start to focus the light well on a distant target. $\endgroup$
    – Jacob C.
    Jan 14, 2020 at 0:18

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