Building the ultimate Solar System part 5: putting the pieces together

We are building the ultimate Solar System.    In Part 1 we chose the right star.  In Part 2 we chose the right planets. In Part 3 we chose the right orbits for the planets.  In Part 4 we learned two ninja moves about how more than one planet/moon can share the same orbit.

Today’s job: putting it all together to build the ultimate Solar System.

Let’s look at our ingredients.

  1. A star a little smaller than the Sun (50-70% of the mass of the Sun).
  2. Worlds (planets or moons) between half and twice the size of Earth, with between one-tenth and ten times as much water as Earth.
  3. Any other accessories that we might need (e.g., gas giant planets).

We can arrange these ingredients in any way we choose.  Our goal is to pack as many worlds as we can into the habitable zone.  We can use our ninja tricks (co-orbital planets and moons).  But the system must remain stable for billions of years.  It won’t do us any good if there is a dynamical instability that sends a bunch of habitable worlds falling onto the star.

I am torn between two ultimate Solar Systems.  Both are awesome.  The first one only contains Earth-sized planets.  The second also includes gas giant planets with Earth-sized moons.

Let’s build these suckers!

ULTIMATE SOLAR SYSTEM 1.  Let’s only include Earth-sized worlds.  No gas giants.  As we saw, the number of planets we can cram into the habitable zone depends on how big they are.  Bigger, more massive planets need to be more widely spaced.  And for maximum orbital compactness we want planets that are all the same size.  I’m going with planets that are half the mass of Earth (about 80% as big as Earth).  Planets of this size definitely satisfy the criteria for habitability.  I guess I’m a little nervous that the very smallest planets in our chosen mass range might be borderline habitable.  And we don’t want to end up with a system full of Marses!

We can fit six stable orbits into the habitable zone.  Each orbit has two sets of binary Earths.  These are Earth-sized planets with Earth-sized moons.  Each binary planet is in a Trojan (co-orbital) configuration with another binary planet, separated by 60 degrees on their orbit around the star.

Six orbits.  Two binary planets per orbit.  Two planets per binary. That makes 24 habitable worlds in a single system!

Here is what the system looks like.

Our first ultimate Solar System. Each orbit around the star (thick gray line) contains two pairs of binary Earths in a co-orbital (Trojan) configuration.  The green shaded area represents the habitable zone.

Most of the worlds are Earth-like in composition with oceans and continents.  But I threw in a few water worlds and few desert worlds.  Good vacation spots!  I especially like the binary Earths that consist of a desert planet and a water world.

ULTIMATE SOLAR SYSTEM 2.  Now let’s include gas giant planets.  We can fit the orbits of four gas giants in the habitable zone (in 3:2 resonances).  Each of those can have up to five potentially habitable moons.  Plus, the orbit of each gas giant can also fit an Earth-sized planet both 60 degrees in front and 60 degrees behind the giant planet’s orbit (on Trojan orbits).  Or each could be a binary Earth!  What is nice about this setup is that the worlds can have any size in our chosen range.  It doesn’t matter for the stability.

Let’s add it up.  One gas giant per orbit.  Five large moons per gas giant.  Plus, two binary Earths per orbit.  That makes 9 habitable worlds per orbit.  We have four orbits in the habitable zone.  That makes 36 habitable worlds in this system!

Here is what it looks like.

Our second ultimate Solar System.  Each orbit around the star (thick gray line) harbors a gas giant planet orbited by five large moons.  There is also a binary Earth in both the leading and trailing Trojan points with the gas giant (60 degrees in front of and behind the giant planet in its orbit around the star).
Our second ultimate Solar System. Each orbit around the star (thick gray line) harbors a gas giant planet orbited by five large moons. There is also a binary Earth in both the leading and trailing Trojan points with the gas giant (60 degrees in front of and behind the giant planet in its orbit around the star).

As in ultimate system 1, most worlds are Earth-like with oceans and continents.  With the odd ocean planet and desert planet for vacations (or, why not, for prisons).  There is a lot more variety than in ultimate system 1 because the planets don’t have to be the same size.

The systems of large moons around giant planets would feel the effect of tides.  I made the moons a bit smaller than the planets within the binary Earths to avoid making tides too strong (since they can cause massive volcanism).  Realistically, the innermost moon of each gas giant might very well get roasted by volcanoes, like Io orbiting Jupiter.  That would still leave 32 habitable planets in the system.  Not too shabby!

Which should we choose as the most ultimate?  Ultimate Solar System 1 or 2?  Hmm……

Here comes a ninja master move!  We don’t have to choose between our two ultimate Solar Systems.  We can put them both in a binary star system!  Of course, binary stars do pose a threat to planetary systems.  This was actually the subject of my very first post on this blog. A binary star that is too close destabilizes orbits in the habitable zone.  A binary star that is too far away gets kicked around by very distant stars (really!) and ends up disrupting planetary systems.  But a binary separated by about 100 AU should not disturb the orbits of our ultimate systems.  Especially since the habitable zone is pretty close-in.

The ultimate Solar System. It consists of two of our chosen stars orbiting each other at a distance of about 100 Astronomical Units (= AU; 1 AU is the Earth-Sun distance). Each star hosts one of our ultimate Solar Systems.

This is my ultimate Solar System.  Two of our chosen stars on a wide orbit.  Each hosts one of the systems we just built.  That makes a total of 60 habitable worlds in a single system! 24 in ultimate system 1 and 36 in ultimate system 2.  That’s why this is the ultimate Solar System!

The ultimate Solar System makes a great setting for storytelling.  Just imagine!  Wars between moons orbiting the same gas giant planet.  Coalitions, alliances, trickery!  High-end worlds with their own dedicated beach moons.  Worlds launching long-range missiles at their Trojan counterparts.  Intelligent beings who learn orbital dynamics at a very young age.  Prison worlds that revolt!  Plus, if one species took over all of the worlds orbiting one of the stars, there could be a whole other series of battles with the worlds orbiting the other star.

There you have it.  The ultimate Solar System according to me.

Update: The Building the Ultimate Solar System saga continues in part 6, where we pack even more planets into a system with many stars.

[There is an awesome game called Super Planet Crash that lets you build your own planetary system and see how the orbits evolve.  It’s super addictive so watch out!]


EPILOGUE: To finish things off, let’s get to the why.  Why did we go through this exercise?  What was the point?  This is a question I ask myself on a weekly basis.  With all sorts of problems affecting humanity — global warming, terrorism, obesity to name a few — why do I spend my days thinking about planets so far away that we will not reach them in our lifetimes? 

I don’t have an answer that will satisfy everyone.  I don’t even have an answer that always satisfies me.  I admit that I do get into funks during which I can’t justify what I do to myself.  I get seriously bummed out.  But whenever I talk with almost anyone about what I do, they are fascinated.  People love astronomy.  They love planets.  They want to hear about planets around other stars.  Planets that could have life.  And they want to know the answers to the questions that I’ve been asking.  Honestly, I think it is that interest from other people that gets me through those funks.  That reassures me that I’m doing something worthwhile.  Something that people care about and are interested in.  And that makes me want to spend time writing this blog.  To get people thinking about planets and life.  To keep people using their imaginations and asking questions.  And to show people that science is inherently fun.

So thank you to everyone who has ever been interested in what I do and given me a boost.  Thanks to several of my teachers.  Thanks to my friends (Andrew West, Ken Sherbenou, Jonah Shaver and Franck Selsis come to mind).  Thanks to my parents.  Thanks especially to my wife Marisa and my sons Owen and Zachary.  You make this all worthwhile.


81 thoughts on “Building the ultimate Solar System part 5: putting the pieces together

  1. Could you go further and make it a trinary star system, considering how far out Proxima Centauri orbits from Alpha Centaur A and B? Or would that run afoul of the whole “distant stars disrupting orbits”? Granted, it would just be more of the same type of thing as the two ultimate star system models.

    Fantastic exercise though, and I’d love to find a “planet village” like this. I’m at least hopeful we might find star systems with 5 or more planets crammed into the habitable zone, considering that we’ve found them with six or more planets crammed inside the orbital distance of Mercury. I wonder what that would be like to live in such a system, with such closely spaced planets and so many potential habitable ones. Astronomy would be something else.

    1. Brett, you could indeed make this a triple star system or even a pair of closer binary stars (4 stars total). The trick is to do it in a hierarchical way. Two stars just far enough away not to perturb each others’ habitable zones (say, orbital separation of at least 10 AU). Then, the other star (or stars) would need to be farther away, say at a few hundred AU. I considered doing that but didn’t want to keep adding too too many layers!

    1. Well, tidal effects — specifically tidal heating — from interactions with the star would not be too bad because the habitable zone is far enough away from the star. However, some of the giant planet moons may undergo pretty strong tidal heating. I would argue that this should only create problems for the innermost large moon of each giant planet, or in the worst case for the two innermost moons. So, you should still have 3-4 habitable moons per giant planet. Not too bad!

  2. This is a cool thought experiment, I had fun reading it. I came up with a few questions though.

    1) Are gas giants possible within the habitable band of a star? I mean I know the orbit math works, but do we have exoplanet evidence of them, or know enough about how they form to say for sure they’re possible? Seems to me that the thermal difference that much closer to a sun would make for significantly different chemistry and formation process, but I don’t know enough about it to be sure.

    2) Did you do any calculations about what the tidal forces would be like on these worlds? I know as a thought experiment we’re not talking about making them suitable to evolve life, just habitable for transplanted life. However if the tides are too great, that changes what works for continental structure, and amount of oceans. Not to mention plate tectonics.

    3) It’s cool that everything is orbitally stable, but what about rotation? Those same tidal forces are lengthening our days by bleeding off rotational speed, would greater tidal forces be more extreme?

    No pressure to answer, these are just what popped into my head. If you addressed them in your earlier posts, I’m sorry I missed them. I plan to read them soon.

    1. Hi Chris — great questions!
      1) There are lots of giant planets known in the habitable zones of their host stars. There are several websites where you can see the distributions of known planets — my favorite is

      2) Tides are definitely important. I discussed that a little bit with regards to choosing the right star. Tidal heating can in principle help trigger plate tectonics by providing a source of internal heat. Of course, too much internal heat is bad so you only want a bit. Tides are strongest on the large moons of the giant planets.

      3) Many of these planets may be rotating very slowly. A single planet left in the habitable zone of a star half the mass of the Sun will have its rotation synchronized with its orbit. Like the moon orbiting the EArth, the planet will always show the same face to its star. But, there are other planets around. Binary Earths will probably always show each other the same face. And the moons of the giant planets will probably always show their giant planet the same face. Most of these worlds will have days that are a lot longer than an Earth day, probably in the range of a few days up to a month. I don’t think that should have any bad consequences for life, although it’s something interesting to explore.

  3. This is amazing!

    People have already asked questions about tidal forces that I wanted to ask. I have two other questions that you may already have covered in

    1) Would it be possible to have a second set of planets 180 degrees across the sun? That would double the capacity of each system giving you a total of 120 planets?

    2) Magnetic fields play a critical role in making planets habitable. How would strong tidal effects affect these magnetic fields?

    1. Good questions Hardik!
      1) Planets separated by 180 degrees are generally unstable.
      2) Magnetic fields are tricky. Some people think they are really important for the survival of the atmosphere and life but some people think they don’t really matter. The ultimate Solar System planets will be spinning more slowly than Earth. This could make it harder to have strong magnetic fields (although there is some debate on exactly what triggers the conditions in the core required to start up a magnetic field).

      1. Can you explain why planets separated by 180 degrees are generally unstable?


    2. The 180 degree separation is the L3 LaGrange point of each respective system – but the L3 point is generally unstable and requires at least minor station-keeping (regular application of thrust to keep it from falling out of position).

      As for explaining the instability – imagine you have a hemisphere bowl and a marble. If you put the bowl round-side up, and place the marble on the top – that’s basically the stability of the L1, L2, and L3 points – it’s stable only so long as you don’t touch it or breath wrong. If you instead place the bowl with the round-side down, and place the marble inside it, you have a rough approximation of the stability of the L4/5 points – if the marble moves a little, it may continue to wiggle about, but it’ll stay in the bottom of the bowl unless you give it a big shove.

  4. Hi Sean,
    Are even mass co-orbitals 60 degrees apart stable? I thought I’d read that the mass-ratio for Trojan planets, between Primaries and Secondaries, is <0.05. Thus you could have two 0.2 Earth-mass Double Planets sharing an orbit with a single 4-Earth mass Super-Earth.

  5. What about Klemperer Rosettes? Could you do alternating gas giants and binary worlds (three of each per orbit) so that each binary world is in the Trojan point of two gas giants?

    1. Cool idea. That would put the really massive planets 120 degrees apart. A system with two gas giants separated by 60 degrees on the same orbit can be stable. Separated by 120 degrees they are unstable

    2. Klemperer Rosettes are unstable over geologic timescales. Any perturbation from the ideal configuration will lead to oscillations which will eventually destabilize the configuration. I have managed to build double Klemperer Rosettes (two orbits of 6 planets each) in Super Planet Crash that survived the duration of the game, but that’s a cosmological blink of an eye. I’d guesstimate that it’s stable on the order of 1000-100,000 years

  6. Why are you thinking in two dimensions? Allowing for orbits in additional orbital planes (and carefully adjusting to avoid collisions at intersections) would allow you to add nearly infinite planets to your ultimate solar system…

    1. Good question Mike. It’s a little counterintuitive but it turns out that a 2-D (disk-shaped) set of orbits can pack planets more tightly than one in which planets can have “3-D” orbits. By 3-D I mean that the orbits can have large tilts between them (called “mutual inclinations”). The reason is that it is the gravitational interactions between planets that determines how tightly their orbits can be packed. These interactions change the shapes of the orbits and can make them more elliptical (“eccentric”). You can’t pack elliptical orbits as close together as circular ones because the closest approach bewteen the two orbits becomes smaller (so the gravity is stronger and the orbits can become unstable more easily). Orbits that have large inclinations (tilts) act to excite eccentricity. So, a system with all the planets in — or at least close to — the same plane can be packed more tightly than a system in which the planets have large inclinations between orbits.

  7. Interesting! You have probably created a new version of mega-engineering envisioned for extra-terrestrial civilizations. Building such dynamically saturated system is certainly much easier to do than a Dyson’s sphere or a Neven Ring World.

    I am wondering if you could make a stable habitable satellite around a binary Earth? If you bring the two biggest Earthlike planet right to the Roche limits can you put a a very small habitable moon within the Hill sphere of the binary system?

    Also, could you have habitable troyan of a habitable moon arond a jovian planet.

    In both case, multibody interaction and particularly the tidal dissipation would be critical to the long term orbital stability of such system.

    1. Interesting questions Yvan! Let’s take them one at a time.

      First, I’m assuming this system forms naturally from a protoplanetary disk — no mega-engineering required. However, if an intelligent species wanted to pack more planets into their habitable zone, this would be one architecture to choose. I think the only way to do this would be to build the planets/moons in-situ on these orbits. To build them elsewhere then move them would be extremely difficult from an energetic point of view. Plus, you would have to overcome some orbital stability issues.

      Second, could you have a stable habitable satellite around a binary Earth? Sure, why not? In principle, this is the same idea as having a planet orbiting a close binary star system. However, this is a little tricky since the binary Earth is in orbit around the star, and the orbital stability of a satellite would need to be close enough that the binary Earth’s gravity dominates the star’s. In fact, the Earth-Moon separation is about 1/4 of the way to that boundary. Prograde orbits (where the satellite orbits in the same direction as the orbit around the star) are stable out to only half that distance, whereas retrograde (satellite orbit is opposite the orbit around the star) orbits are stable out to that full distance. Tides would push the binary Earth to a separation comparable to or larger than the Earth-Moon separation, so that does not leave much room for a satellite. Much farther away from the star this would be easier because the radius within which a planet’s gravity dominates the star’s would be larger. But for small (Sun-like or smaller) stars I doubt such satellites could be stable.

      Third, could you have a Trojan companion to a habitable moon? Why not! Think of the giant planet as the star. You could put two same-sized moons on the same orbit separated by ~60 degrees and they should be stable for long timescales. There are some issues with regards to the stability if tides are very strong, so it’s possible that a trojan companion to the innermost moon might not be stable. But, this should be fine for the ones farther out. Good idea! This could potentially pack a few more habitable planets per gas giant!

      1. The idea could even be pushed further. For example, you could have binary habitable moon pairs and two singles troyans per stable orbit around a giant planet or simple two pairs as you solar system model. Hence, 4 moons per orbit around a gas giants.This brings the possibility of having 4×5 habitable moon per giant, with 5 giants + 5 x 2 pairs. You get 120 habitable world per star.

        I think you would need some kind of physical simulator coupled with a genetic algorithm to explore the stability of the most extreme gravitational configurations over billions years.

        If you have a simulator in hand, we could write a paper toghether on this news mega engineering technology, in the context of SETI?

      2. Yvan — why not? It’s worth pushing this as far as it can go. I get 4 gas giants x 5 orbits per gas giant x 4 moons per orbit + 4 x 2 binary Earths = 96 planets per system. I think you included 5 gas giant orbits instead of 4.

        I’m not sure that shrinking this down — with Trojans and binaries around gas giants orbiting a star — will be stable, because there are some processes like tides that are not scale-invariant. Plus, we can’t shrink the planets down any more. Still, it’s worth testing! There are several off-the-shelf N-body codes that can be used to do this — for example, the Mercury integrator (written by John Chambers) is very user-friendly. I’m happy to help out with this — the trickiest part will be generating the initial conditions I suspect.

      3. N body code is one things, but tides are a serious issues too. To much tides and your moons ends up Io like and you don’t want that. However, some tide might be useful on the smallest planet to maintains the plate tectonics. Also, tides are a dissipitative process. Over time, they will destroy your nice orbital stability.

        As for the exploration of the possible space, this will a rather hard problem. We have potentially 100 planets. With seven parameters per objects (3 vi+3 xi + mass), the phase space will have 700 dimensions + stellar mass. Hopefully, rule of thumb allows the reduction of the search volume by a large factor. Still, this will be a hard problem.

        Might worth doing. I am an observational astrophysicist. Not a numericist. This might be a useful training for me.

  8. So is there enough of the right elements in the sun to “mine” them and build this structure? Thus reducing the mass of the sun in the process and changing it into a smaller mass star with an enhanced life span? If faster than light travel is impossible, might this be what sufficiently advanced civilizations end up doing? If we can’t move, can we make our solar neighborhood the best it can be by building these? Also, what are the chances of finding one of these megastructures as a sign of intelligent life, how far could we detect these systems?

    1. Like I mentioned in my reply to Yvan, the idea was not to build this system but rather for it to build itself from a protoplanetary disk. Each piece of the puzzle is completely scientifically reasonable and is either directly observed or expected from theoretical work. The part that is a little outlandish is to put all of those pieces in the same system.

      But, what if some intelligent species wanted to upgrade their planetary system to include more habitable planets? Well, each extra world would require about half of an Earth-mass in rocks. You could try to mine the star, but that stuff is both hard to access without getting fried and highly diluted — the star is mostly gas. It would be much easier to grab this mass from other bodies in the system. Maybe asteroids or comets. About 15-20% of Sun-like stars are thought to have massive outer belts of comet-like bodies. That might be a good place to grab the mass, then move it inwards.

      Now, finding this kind of system could be tricky. The individual components are detectable now with the Kepler space telescope. But, piecing it all together to recover the true nature of the system would not be an easy task! A good project for a very dedicated graduate student!

    2. In terms of mega-engineering – building a Ringworld, Dyson Swarm, or Matrioshka Swarm are all much more effective than engineering this sort of super-system. As an example, a ringworld (the easiest to build) built at Earth’s orbital radius and only 40 miles across would have more habitable surface area than the 60-world Ultimate System Sean proposes. Assuming we can overcome the materials science hurdles, we can do so with a mass less than that of a single Earth. (Planets are a very inefficient use of mass to create habitable area). It might be possible that the super-system would be cheaper (energy-wise) to build than the mega-structure, but it would strongly depend on the starting conditions (i.e. a system as close to this ideal as possible) to reduce “transit costs” of hauling matter from far away.

      Finding this sort of megastructure (super-system) as a sign of intelligent life would be pretty difficult. We have the tech (i.e. Kepler spacecraft and processing time), but we’d need ~400 Kepler-like satellites watching the sky to cover it all, but the Kepler method (transit) can only detect systems whose ecliptic plane is edge on – assuming a 5 degree window, that means we’d only be able to detect ~2.8% of planetary systems. Furthermore, we have a range limit of (near as I can find the farthest Kepler planet is ~7000 parsecs) ~23000 light-years. That’s roughly 1/4 of the Milky Way – which isn’t a lot in the scale of the universe. We do have other methods of planetary detection, but they have similar (or greater) range and coverage limitations. Basically, finding planetary systems is relatively easy – but finding specific planetary systems is still darn hard.

  9. So… leaving aside all proponents of Dyson spheres and the like… under what conditions would you actually grant a speculative fiction writer the use of this idea or other ideas you develop? Just asking. (I just saw this via NEW SCIENTIST and reblogged your lead article. I’ll reblog this one too.)

    And I submit I know why you’re driven to do this sort of thing, but if I told you I seriously doubt you’d believe me.

    1. First of all, thanks for the re-blog! I appreciate it.

      I hadn’t thought of the ideas in the “ultimate Solar System” as being proprietary. I had figured that once I posted about them, they are out there to be used and built upon. If you’re interested in delving into this in some sci-fi realm, let me know (personal email probably) but please don’t feel like they are private ideas.

      And I’m curious to know what you think my motivation is!

      1. Thank you! You are most gracious – I will give you credit whenever and wherever it’s due. My life circumstances may or may not allow me to develop my fiction beyond where it is. But you’ve given me the perfect complex around which my Rim Confederacy and its demigod leader may be built. It could even be a double star of the halo population and immensely old, like nearby Kaeptyn’s Star.

        Your – my – our motivation to think about such things can only be accounted for if we were designed and destined to inherit the Universe, on the truly divine level of character and power required to do so and on the initiative of its Creator. I don’t believe in the kind of luck required to make that child of naturalism and scientism as confused with natural science, evolution, work for even the smallest self-reproducing units within the lifetime of the Universe. I’ve done the math. Minds far greater than mine have done the math (some, amazingly, have remained evolutionists anyway). Were the real universe 10 EE 100 times the size of the visible universe – in fact one could almost increase the scale from there arbitrarily, just given Julian Huxley’s estimate of what it would take to evolve a horse – our Earth and life upon it could never happen within the lifetime of the universe. And yet we are here. There must be a purpose behind our being here and our drive to inherit the stars must be related to that purpose. We may not be aware of where our drive arises, but humility requires we follow that evidence where it leads to its only credible source.

        My fiction pulls many, many things together, not least an allegory of that purpose, but also astronomy, personality type theory, languages, music and indeed everything I’ve ever found interesting (which is pretty much everything). Whether I will now have time to continue in writing it remains to be seen.

  10. This was a truly fascinating read. I have two questions. First: did you play with your model in Universe Sandbox ( Second: I always wondered if it’s possible (in terms of celestial mechanics) to have more orders of host-satellite systems than only our old, two-step sun-planets, planet-moons. Let’s say we have a brown dwarf orbiting sun-like star in its habitable zone which in turn has its own mini-system of Jovian planets, each of sporting yet another mini-system of earth-like moons. Wouldn’t such system beat yours in terms of number of possible habitable bodies? Food for thought 🙂

    1. I’d also like to see if anyone has made this system work in Universe Sandbox. I’ve tried it, but I’m not good enough at the game yet to get it all to work.

  11. All these concepts validate a bit of speculative fiction I was engaged in, though I might have run into something that you might not be aware of: A variant of your “Ninja” move… A Sol-like binary pair with a relatively short orbit of 10-60 days creates an expanded habitable zone. My calculations seem to indicate at least a 5th gas giant may be possible under these circumstances.

    1. Hi John — interesting point. The result that you linked to proposes that binaries are better for life because the stars slow their spins faster due to tidal interactions. Fast-spinning stars emit more radiation, which is thought to be bad for life. The authors claim that Earth and Venus would have more water if the Sun were a binary. This is a bold statement because no one actually knows a) exactly how and when Venus lost its water, or b) how much — if any — water Earth has lost. Still, I think their point that binaries “calm down” faster than single stars is intriguing and could indeed tie in with habitability. However, I don’t think that this would widen the habitable zone.

  12. hmm i had an idea like this the idea was of a planet named librum that moves on a figure 8 orbit around 4 dwarf stars that may sustain life.the biggest star that i named f237 has 3 planets orbiting while the others have eitheir 2 or 1 planet orbiting them. Also librum would be habitable as it moves very fast just not fast enough to knock it off its orbit

  13. Another question: why not have your habitable world pairs in rosettes, so that there would be six world pairs in each orbit, each helping to keep the others stable by mutual – what would you call it? Lagrange-point resonance? Then you could have two orbits for your 24 worlds rather than six orbits. In the other star system, since it has gas giants, you’d have to do something different.

    I ask this because my own idea for an “ultimate” star system (kinda not-so-ultimate 🙂 after seeing your work here), which I called the Homeworld Rosette, involved six planet-moon pairs in just such an arrangement as I suggest. One possible improvement would be to make three of those planets (forming an equilateral triangle with each other in their solar orbit) gas giants, so as to help anchor the others – and the gas giants, naturally, could have at least one habitable moon apiece.

      1. Sean that is not a criticism but a compliment even if it doesn’t seem that way. Astronomy is and always has been a fascinating world to me. Complex because it is so intricate in all it’s splendid detail. And it can sometimes become confusing simply from all it’s intricacies . But that makes it so challenging and that was the other part of the fascination I have with it. So goid post is what I was saying.
        I desperately wanted to be an astronaut. Now an older astronaut in my heart.

  14. Part of your motivation for doing this seems to have been the desire to create the ultimate venue for a science fiction story. If you want a story that doesn’t use FTL, then this is a way to get lots of habitable planets close enough together that even 20th century technology would be sufficient for interplanetary travel between inhabited worlds.

    On the other hand, once an intelligent lifeform evolves in the ultimate planetary system and achieves 20th/21st century levels of technology would the highly structured nature of this system tip a balance between science and religion? Just as we are beginning to learn about extra-solar planets, our fictional aliens would begin to search for other planetary systems and they would quickly learn how unlikely their own system is. For earthlings, all we need is a planetary system with an earthlike planet in the habitable zone and we are impressed. Our aliens would look at other systems and probably not see any nearby stars with 30-60 habitable worlds. The ultimate system seems engineered rather than natural (as a couple of other comments have suggested).

    How could our aliens in this ultimate planetary system avoid seeing this bounty of local worlds as the gift of a beneficent creator deity?

    1. Respectully, maybe you should ask first why so many don’t see Earth and life itself upon it as prima facae evidence of the existence of God. Am I the only one in the immediate neighborhood who has “done the math” and seen how totally beyond absurd the idea of a naturalistic origin of life is, on Earth or anywhere else?

      A star system such as is constructed here would only compound the problem for anti-theists – by orders of magnitude. Like life itself, like any sophisticated construct of man (such as the Space Shuttle), such a system would use the properties of matter without being dictated by the properties of matter. Such a system would require information imposed on matter by intelligence, again just as much as life itself does.

      I asked permission to use this construct in my own speculative fiction, and I don’t dodge the issue in that fiction. The system, in my Metacosmos, was indeed constructed by a powerful intelligence – although not the Creator of all but a created being who thinks he “knows better” and is being permitted to try to prove it. That fact is part of the plot, should I ever publish it.

  15. Hi Sean,
    Great series of posts! I have two questions regarding life on your three ultimate solar systems:

    1) I heard that Jupiter and Saturn act as gravity wells to ‘mop up’ incoming threats like asteroids etc, that might otherwise hit Earth(s). How do you see this in your solar systems where everything is more tightly packed together? Would there be more risk of incoming space debris?

    2) I was wondering how you see the Oort cloud objects interfering in your third, ‘ultimate’ solar system. Would they not hit the inner solar system planets in a double star system?
    Thank you!

    1. HI Jeroen — good questions. Here are some answers:
      1) Jupiter does indeed act as a “protector” of Earth by deflecting and ejecting a large fraction of the comets/asteroids that would otherwise be on Earth-crossing orbits. The trick is: those comets/asteroids would not be on those orbits if not for Jupiter. It’s a circular argument: Jupiter is essentially protecting Earth from Jupiter. It’s like a bully telling you how important he is because he is stopping himself from punching you. Studies that account for this have shown that Jupiter’s importance is actually pretty small — not zero, as it does protect us somewhat — but small. (See here for details:….146…16L

      2) You’re right that in a binary star system, a Kuiper belt could potentially be a source of impactors on the planets orbiting each star. However, a Kuiper belt would not last very long because it would be emptied as it provided impactors. There is a balance: rare impacts that could last a long time (say, billions of years if the configuration of the belt is just-so) or many impacts for a very short time.

  16. Give this dude a Genesis Device from Star Trek and a nebula to provide raw material to work with and stand back!

  17. Now that we’ve seen the ultimate Shangrai-La solar system configuration which is utterly, utterly unlikely ever to be seen in nature, show us what the ultimate realistic solar system might look like given what we know (or at least suspect) is going on in the vast depths of space. You need to factor in a whole plethora of both interior and exterior forces and factors to come up with a more realistic scenario. Planetary migration, gas & dust density w/i a proto-planetary disk, planetary demographics based on the Kepler census (which planets are most common and therefore most likely to be in a given solar system, etc.), interplanetary celestial mechanics, extrasolar celestial mechanics, average proximity of the solar system to dangerous star systems, etc. The list of factors is quite lengthy and quite formidable so you’ll have to make a few “fudge factor” assumptions to allow you to construct such a system w/o having a super-computer at your disposal. Good luck! Chao!

  18. In the Ultimate Solar System I could the binary terrestrial lagrangians be replaced with jovians and their moons? What do we call these bodies anyway? the moons are fine, but the rest would not be called planets by the IAU if they were in our solar system, at least…

  19. I have a question for you. Im not sure if you’ve covered this; im new to your blog, so if you have a link would be appreciated. But i hear that in order to have a habitable planet, a gas giant must exist in its solar system to catch asteroids with its gravity field. My question is: are there other requirements for what a solar system should be comprised of to possess a habitable world? And if its relevant, a solar system im asking about would have a red dwarf. (Its for a story lol) thanks!

    1. HI Rudy — that is a far-reaching question! Let me answer you in steps. First up: is a planet like Jupiter really needed to have a planet like Earth? Maybe, but not for the reason you mention. It was indeed suggested in 1994 that Jupiter protects Earth from asteroid and comets that might impact us. This has recently been proven false. With no Jupiter Earth would actually get hit less. Jupiter protects Earth from comets that Jupiter had already kicked onto Earth-threatening orbits.

      But it is likely that Jupiter played a role in shaping the Earth during its formation. For example, in the Grand Tack model ( Jupiter is key. I have some new ideas on the subject that I’ll write about soon.

      Now, what other factors are vital for planetary life? Well, the simplest one is a planet with liquid water on its surface (or maybe its subsurface). Pretty much everything else is debatable. Some people argue that a large moon is vital to stabilize the planet’s spin axis (I don’t think that’s true). Others argue that plate tectonics is vital (I’m not sure about that one). And some people think that solar flares are really dangerous (I’m up in the air on that one too — more study is needed).

      Hope this helps — I’m happy to answer more questions if you have them.

      cheers, Sean

  20. Sean, I love your constructed solar system. I am a wannabe novelist participating in Nanowrimo this year. I want to attempt a novel based on people living on your ‘ultimate solar system 2’ with 36 planets. I will be very clear where the schematics came from and also that you do not endorse my usage. Is that enough? At this point, in Nanowrimo there is no money involved and no one will see my work. Later, they may. What sort of attribution is appropriate? Or would you prefer I cease using your creative work?

    1. You are welcome to use any of the systems I create for storytelling. I appreciate some acknowledgment of where the system came from — a simple sentence somewhere in the “thanks yous” is fine. I’m always really glad when people want to use these settings for stories!

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