What is the theoretical maximum number of habitable planets in one solar system?
In the DC comic book universe, the Vega System is a solar system around the star Vega (Alpha Lyrae), which is depicted as having dozens of habitable planets. While it seems to be an implausibly large number, it does make me wonder: what star type and arrangement allows the theoretical maximum number of human habitable planets (or planet-sized moons) in a solar system?
I'm guessing that the answer would probably involve multiple, massive super-Jupiter planets orbiting in the star's Goldilocks zone, each of which has multiple habitable moons, as well as having more habitable planets in their L4 and L5 Lagrange points, but I'm not well-versed enough in the math to work it out for myself.
Since stellar mass is inversely proportional to the lifespan of the star (or, at least, negatively correlated with lifespan, if it's not strictly inversely proportional - again, not familiar with the math), having a super-massive star with a large Goldilocks zone isn't helpful if the star dies before life evolves, so it'd need to have a lifespan of at least several billion years to let life get started.
This post was sourced from https://worldbuilding.stackexchange.com/q/151028. It is licensed under CC BY-SA 4.0.
1 answer
This is based off the information found in the link provided by Juraj.
The answer is 2,862,106 earths in the goldilocks zone
How to get 2,862,106 earths in habitable orbits:
Rules, they have to all be exactly the same mass.
Multiple planets can be in the same orbit, so long as there are at least 7, and they are at least 12 hill distances apart.
You can pack rings together tighter if alternate rings orbit in opposite directions.
First, start with a super massive black hole of 1,000,000 solar masses.
The Schwarzschild radius of this black hole is .02 AU, or 3,000,000 km. The closest stable orbit is .06 AU.
Put the Sun into orbit around it at .2 AUs. The black hole does not emit light of course, but the sun will, so this will give us a habitable zone. Of course the tidal forces on the sun will rip it apart into an accretion disk, but it will still be emitting light.
Because of the 1,000,001 solar masses of the black hole/sun system, the hill radius of each earth is 1/100th smaller than it would be around the sun itself. So you can put 4154 planets in each ring of planets.
If alternating rings are retrograde, you can put 689 rings in the suns habitable zone.
Alternately, you could avoid having the sun ripped apart into an accretion disk by having a ring of 9 suns evenly spaced in an orbit at .5 AU. The extra solar radiance would push the habitable zone out a ways, but otherwise the number of planets and number of orbits stays the same.
Another possibility would be to put the suns on the outside, with 36 of them orbiting in a ring at 6 AU. This would mean that each planet would get light from every side, meaning there would never be night time.
Downsides:
- You aren't going to find a system like this in nature.
- Each planet would be orbiting very fast, going around the black hole every 9 hours instead of 365 days. So the planets would be moving at about .1 C.
- Planets in different orbits would be affected differently by relativity, and people on planets with closer orbits would be aging slower than people on further orbits.
- Because of the orbital speeds involved, you would never be able to visit a planet in another orbit. But there are over 4000 planets in your orbit, and they would be stationary relative to you, and only about the distance of earth and the moon apart, so travel between them would be almost trivial. If they became tidally locked, you would be able to travel between them using a space elevator.
0 comment threads
0 comment threads