Inhabitable Planets Too Close Together?

One thing that I have noticed in the Honorverse, is there appears to be too many human inhabited planets too close together. Considering how huge the Galaxy is, could the story lines have worked better if the distances quoted were about 10X to 20X as far..or even greater? A little thing and just me. HB of CJ (old coot) I love it here.

HB of CJ wrote:One thing that I have noticed in the Honorverse, is there appears to be too many human inhabited planets too close together. Considering how huge the Galaxy is, could the story lines have worked better if the distances quoted were about 10X to 20X as far..or even greater? A little thing and just me. HB of CJ (old coot) I love it here.

Steller density in our region of the galactic arm is about .004 stars per cubic Light Year or 250 LY^3 per star. This works out to an average spacing of about 6 LY. If we assume that only 1/10 of stars have habitable planets then the average distance between habitable planets is about 14 LY. This suggests that you should have about 360 habitable planets within a sphere of about 100 LY diameter.

It is interesting that inhabited planets are far closer together in the SL core. Given no FTL for early colony ships, they could not be picky. Given hyperdrive, Warashawki sail then wormhole networks humans got much pickier.

Please remember that the Honorverse was designed in the early 1980s. If you had walked into an astronomical convention then and claimed that the solar system originally had five gas giants, that Jupiter and Saturn wandered in and then out, shoving Uranus and Neptune in front of them and ejecting the other planet from the system entirely, you'd have been laughed out of the room with disparaging comments about Velikovsky.

Today, that happens to be the leading theory of how the solar system formed.

The Nice and Grand Tour models work reasonably well in explaining this system, but not so well in explaining everything else we're seeing.

Regardless of the overheated press releases breathlessly announcing "earth-like" planets, there are a lot of questions as to how accurate any of those estimates are.

Just for starters - most of the systems we've seen have a lot of planets very close to their primary - way inside the orbit of Mercury. There are a lot of systems with very disturbed orbits - nothing like the nice, neat layout of our system. That may be an artifact of what we can detect, but still, it's interesting.

Earth and Venus are very similar. So why does Venus have a very thick atmosphere and Earth a much thinner one? That's probably a result of the hypothesized collision that formed the Moon, together with tidal stresses from the Moon on the atmosphere. How likely is that scenario to be repeated elsewhere? Some places, sure. All that frequently? I have no idea, but I'm not optimistic.

Moving habitable planets farther apart would have stopped the first wave of expansion before it began - the distances would have been totally infeasible for generation or cold sleep ships.

I have this deep, dark suspicion that the current wave of extra-solar planetary discoveries is saying clearly: "no, we will not go out and colonize the stars." That's not the message people want to hear.

JohnRoth wrote:I have this deep, dark suspicion that the current wave of extra-solar planetary discoveries is saying clearly: "no, we will not go out and colonize the stars." That's not the message people want to hear.

Who says we need habitable planets to colonize the stars?

drothgery wrote:Who says we need habitable planets to colonize the stars?

Yep, the difference between a space habitat and a plausible sublight colony ship is that the habitat doesn't have engines and doesn't need to run for decades to centuries without external resources.

Given the techniques available to detect extrasolar planets, we are unlikely to locate any that are not massive and/or close orbiting.

Even if only one in on hundred stars have habitable planets, they will be less than 30 lightyears apart.

JohnRoth wrote:Please remember that the Honorverse was designed in the early 1980s. If you had walked into an astronomical convention then and claimed that the solar system originally had five gas giants, that Jupiter and Saturn wandered in and then out, shoving Uranus and Neptune in front of them and ejecting the other planet from the system entirely, you'd have been laughed out of the room with disparaging comments about Velikovsky.

Today, that happens to be the leading theory of how the solar system formed.

The Nice and Grand Tour models work reasonably well in explaining this system, but not so well in explaining everything else we're seeing.

Regardless of the overheated press releases breathlessly announcing "earth-like" planets, there are a lot of questions as to how accurate any of those estimates are.

Just for starters - most of the systems we've seen have a lot of planets very close to their primary - way inside the orbit of Mercury. There are a lot of systems with very disturbed orbits - nothing like the nice, neat layout of our system. That may be an artifact of what we can detect, but still, it's interesting.

Earth and Venus are very similar. So why does Venus have a very thick atmosphere and Earth a much thinner one? That's probably a result of the hypothesized collision that formed the Moon, together with tidal stresses from the Moon on the atmosphere. How likely is that scenario to be repeated elsewhere? Some places, sure. All that frequently? I have no idea, but I'm not optimistic.

Moving habitable planets farther apart would have stopped the first wave of expansion before it began - the distances would have been totally infeasible for generation or cold sleep ships.

I have this deep, dark suspicion that the current wave of extra-solar planetary discoveries is saying clearly: "no, we will not go out and colonize the stars." That's not the message people want to hear.

Grashtel wrote:

drothgery wrote:Who says we need habitable planets to colonize the stars?

Yep, the difference between a space habitat and a plausible sublight colony ship is that the habitat doesn't have engines and doesn't need to run for decades to centuries without external resources.

A sub-light cold sleep ship doesn’t need engines that run for centuries, it would help to get them there faster but isn’t “needed”. Only an engine that can get it slingshoted out of the solar system at a high (or at least noticeable) fraction of c, then slow them down enough for a reverse slingshot into the new solar system and to the “landing” area/orbit. The trip itself can be drifted with just generators for the computers & cold sleep chambers.

Space is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is.


[putting on my astronomer hat]
Let's throw out some rough numbers. The Honorverse has settled a volume a bit over 1000 light-years in radius. In that radius, there are almost 17,000,000 stars. Of those, around 3,000,000 stars are of stellar classifications compatible with habitable zones. Toss out two thirds because of other conditions, such as double stars which would disupt planetary systems and you still have 1,000,000 stars which could have habitable planets. It looks like about 1% of those are inhabited in the Honorverse.

We can't tell yet how many of those 1,000,000 systems will have Earth-sized planets in the habitable zone, but we can be pretty sure that almost every one of those stars will at least have planets. No, it is not absurd to have as many habitable systems as Weber has put into the Honorverse, even with today's knowledge instead of the astronomy known back when On Basilisk Station was written (which was before any planets outside the Solar System had been discovered). I expect Weber's number to be higher than reality (which is perfectly reasonable for science fiction), but reality could still have even more than the Honorverse. Ask again in ten or twenty years.

SWM wrote:Space is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is.


[putting on my astronomer hat]
Let's throw out some rough numbers. The Honorverse has settled a volume a bit over 1000 light-years in radius. In that radius, there are almost 17,000,000 stars. Of those, around 3,000,000 stars are of stellar classifications compatible with habitable zones. Toss out two thirds because of other conditions, such as double stars which would disupt planetary systems and you still have 1,000,000 stars which could have habitable planets. It looks like about 1% of those are inhabited in the Honorverse.

We can't tell yet how many of those 1,000,000 systems will have Earth-sized planets in the habitable zone, but we can be pretty sure that almost every one of those stars will at least have planets. No, it is not absurd to have as many habitable systems as Weber has put into the Honorverse, even with today's knowledge instead of the astronomy known back when On Basilisk Station was written (which was before any planets outside the Solar System had been discovered). I expect Weber's number to be higher than reality (which is perfectly reasonable for science fiction), but reality could still have even more than the Honorverse. Ask again in ten or twenty years.

Let's also take into account we really don't know the true native habiliability of these systems in the Honorverse. Yildune, for example has a total of ZERO habitable planets, but a population of hundreds of millions living in space habitats. We know of 6 worlds that humans had to be genetically modified to survive long term in their gravity wells.

It may be possible Venus like worlds were Terraformed "easily" given a discovered technology, and Mars like worlds made habitable through depositing comets into it's atmosophere along with man made green house gases. Long term viability (100,000+ years) of these solutions may be non-existant, but it makes a world habitable now and for their grandchildren.

Some system may have habitable moons around their close in gas giants. Other colonies might have had to build domes or live in tunnels and underground caves for generations. Let's face it, if you can build a space habitat, who needs to use a planet with an atmosophere? Some planets may be nothinng but barren rock covered by domes and habitats.

And with fusion reactors, why limit yourself to systems/locals with strong enough sunlight? Who says your ship didn't have a fault causing you to have to land on that barren rock circling the Brown Dwarf wandering around between stars?

David once said that for every dot on the map, there are 50 lost colonies, failed colonies, "minor" industrial mining ventures, smallish colonies, pirate transfer points, etc, etc that don't just don't count i the big picture of things - Parmelly station is probably one of these.

The truth here is we just don’t know how closely or distantly spaced habitable planets will be. Even with near space data we may not find a single other habitable planet in our entire spiral arm, then come to find the other arm full of habitable planets in nearly every solar system & some more than one. Likewise we may find that the ½ dozen or so of our neighbor stars are dead stars while the rest of the arm is full of habitable planets. These may have intelligent life who are either too primitive to have developed the radio yet or who (for some reason) never developed it & communicate threw some means we haven’t developed yet, or they may not have any intelligent life at all. From our perspective the existence of a habitable planet or intelligent life in any given system is a pure crap-shoot. We could go on to find no other habitable planets in the entire galaxy but then find that this galaxy is unique and most galaxies are teeming with life, or vice-versa. So saying they’re “too close together” is currently meaningless because you have no way to know this.