spaceSpace and Physics

This Is The Maximum Number Of Planets You Can Have In A Solar System Like Ours


Jonathan O'Callaghan

Senior Staff Writer


Have you ever wondered how many planets you could fit around a star? Well wonder no more, because someone has gone ahead and worked it out for you.

Sean Raymond, a US astrophysicist based in Bordeaux, France, decided to set out to build the Ultimate Engineered Solar System in a new post on his planetplanet blog. You might remember his “ultimate Solar System” back in 2014 that could contain 60 Earths.


But for his latest trick, things get bigger and better. He modeled the maximum number of planets you could have in the habitable zone of a star (where temperatures are just right for water). And it came in at a whopping 416 planets.

In his post, Raymond discusses how the planets need to be positioned to ensure their gravity does not cause havoc – known as the Hill radius. This limits the number of concentric orbital planes you can have around a star before a system becomes unstable.

He found that, theoretically, a Sun-like star could support 42 planets in a single orbital plane. Around our own Sun, you could have six rings of 42 in the habitable zone, giving us 252 planets.

However, if you shrink the planets down to half of Earth’s mass, you can have 52 in eight rings, giving a more impressive 416 planets. Raymond calls this the Ultimate Engineered Solar System.



Used with permission via Sean Raymond/

There’s no way this system could form naturally, but Raymond jokes that a super-intelligent advanced civilization could put it together – if, you know, they had planet-building capabilities.

“The new, engineered system is impossible to form naturally,” Raymond told IFLScience. “It is perfectly stable once created, but nature would never build it. But, hey, a very advanced civilization might!”

You can take things a bit further, too, and put planets in other orbits outside the habitable zone, assuming these aliens can make these worlds habitable. Raymond’s “Ridiculous Solar System” would boast a rather astonishing 10,769 planets. Make the planets the size of the Moon, and you can get 65,000 around a single star.


Are any of these things actually possible? Well, not really. But it’s interesting to explore some possibilities for what an artificial system could look like. And who knows, maybe there’s an advanced alien race somewhere putting this together. Until then, we’ll have to make do with our eight (ish) planets.

Used with permission via Sean Raymond/


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