A new size scale for stellar systems

[Malenfant]

LGG and SGG does that quite nicely actually. 160,000 km diameter (80k km radius) seems to be the highest you can get for gas giants anyway, after that the radius stays about the same and they get denser as you add more mass.

Canonically (p39, CT bk 6) SGG are 20k to 60k km in radius, and LGG are larger than that (up to 120k km radius, which is just silly - you can't get them that big). Note that by this definition, Saturn is actually an SGG, not an LGG - its polar radius is just over 60k km, and its equatorial radius is 54k ( http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html ).

The line between terrestrials and SGG is blurry. If a terrestrial is massive enough to hold onto hydrogen and helium, it can become a GG - and that depends on its density, radius, and distance from the star. A world with earthlike density in the habitable zone can hold onto helium around size A, and hydrogen around size C.

 

[Liam Devlin]

Originally posted by Malenfant:

Realistically speaking there might be quite a few of these big worlds - especially panthalassics. These are huge, volatile-rich worlds that are 1-3 earth masses, up to half of which might actually be water and atmosphere. They'd usually be found in the middle zone, between the habitable zone and outer zone.

I know, but seldom does the mainworld fall into those two size categories--I meant at no time those sized worlds couldn't be found within the system.

You raise a good point now with this: In System gen there was once the "Inner Zone", "Habitable Zone" & "Outer Zone". You raise there is a fourth, this "Middle Zone".
Can you tell us more how this M-Zone of the system is defined, orbit wise?

 

[Malenfant]

You don't get B and C mainworlds because you can't officially roll them up in Trav. I have it set so that if you roll a 12 on the 2d-2 size roll, you roll another 1d6 - 1-3 is A, 4-5 is B, 6 is C.

I just did define the Middle Zone

- it's between the Habitable zone and the Outer zone. Mars is in the Middle Zone in our own solar system.

 

[daltoncalford]

Hi All,

My computer generation system, and the manual system that goes with it, led me to a 4d6-4 range for planets.

The same went with hydrographics for a more granular hydrographic value (steps of 5% instead of 10%)

Atmosphere was difficult, as I used the values as steps away from standard vs a straight linear value score.

best regards

Dalton

 

[Space Cadet]

Originally posted by atpollard:
</font><blockquote>quote:</font><hr />Originally posted by Malenfant:
For gas giants you could just use codes D (SGG) and E (LGG) (I'd keep B and C free for 11,000 and 12,000 mile diameter terrestrials). Then you don't have to stick decimal points in the UWP.

I basicly agree, but one of SC's original goals appeared to be to increase the number of possible gas giant sizes. LGG and SGG will not do that.

Is there overlap in size between the largest rocks and the smallest gas giants? At what point is it a planet with a thick atmosphere and at what point is it a small gas giant? </font>[/QUOTE]I don't want all gas giants to be the size of Jupiter when they are large gas giants and the Size of Neptune when they are small gas giants, it seems to me that a more realistic system would have more sizes for gas giants than just two, having just two sizes makes all gas giants "look alike", and I don't believe that to be the case. For instance a Human would be quite confortable in the gravity fields of Saturn, Uranus, and Neptune, but Jupiter would pin him to his seat, and he would move around only with great difficulty. Also Traveller has the 100 diameter Jump rule, easier to know what that distance is, if you know the size of the gas giant.

 

[Malenfant]

They're not all one size though, and never have been - the definitions in CT are clearly variable.

Just pick a number in the right range (20k to 60k km radius for SGG, 60k to 80k km radius for LGG) and mention that in a text note next to the UWP, and you're done.

 

[Space Cadet]

Of course if you lose the text, the referee is going to have to use the UPP to recostitute the gas giant and substitute a new value for the diameter as the term LGG and SGG only give you very approximate ideas of how big the planet actually is for main worlds from 1,000 to 10,000 miles in diameter, you have a better idea of its actual size just by looking at the code, +/- 500 miles of course.

I think using a Hexadecimal planetary code is a good idea.

1 = 1,000 miles
...
A = 10,000 miles
...
F = 15,000 miles
10 = 16,000 miles
...
1A = 26,000 miles
...
1F = 31,000 miles
20 = 32,000 miles
...
2A = 42,000 miles
2F = 47,000 miles
30 = 48,000 miles
...
50 = 80,000 miles
...
70 = 112,000 miles

The format is of course Hex# * Dec#1,000 = diameter in miles or Hex# * Dec#1,600 = diameter in kilometers. What could be simpler, one system for all sorts of planets. The size itself determines whether the planet is terrestial or a gas giant, there is no seperate roll for gas giants. 64 is the Hexidecimal 100. You would need and exponential roll to make the result not, 90% gas giants though.

You could have a table to tables though such as:

roll 1d4
result = roll
1 = 1d10 x 10 meters
2 = 1d10 x 100 meters + above
3 = 1d10 x 1,000 meters + above
4 = 1d10 x 10,000 meters + above

So roll a 1 and you roll 1d10 * 10 meters.

roll a 2 and you roll 1d10 * 100 meters + 1d10 * 10 meters and so forth.

 

[Malenfant]

So don't lose the text then

. It's not like the notes are going to get separated from the UWP anyway.

Think about it - what I'm suggesting keeps the format we have already (UWP + notes) without the need to change anything about that. The problem with what you're suggesting is that it suddenly throws in two-digit codes for one parameter (size), which the UWP is not built for.

I'm talking about something like this:

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Jupiter ADC0746F N So (trade codes) radius: 69911km</pre>[/QUOTE]

 

[RandyT0001]

I would consider changing the hydro from 0 (zero) to either Y or N. If there is skimmable water at high altitudes, like Jupiter, then it would be coded Y. If there is virtually no skimmable water at high altitude, like in Neptune (IIRC), then it would be coded N. I think the availability of skimmable water will have an influence on the overall population the gas giant's floating cities could have. The gas giant would probably need skimmable water to support populations above code 5 (or 6+).
Just an opinion.

 

[Malenfant]

er, you really won't need "skimmable water" at gas giants - remember the air there is hydrogen! you just need to suck in atmosphere, clear out the hydrocarbons and helium and you have your fuel.

 

[RandyT0001]

The water is for the population to drink not to use as unrefined fuel. Jeeze, sometimes I think you scientists can't see the forest for the trees.

 

[Malenfant]

eh, they can drink Slurpy-cola like everyone else

 

[Anthony]

Any outer zone gas giant will have a system of moons with enough ice to make water not really a problem.

 

[Liam Devlin]

You know, there was a sort of sideways mention of "middle zone" in the TNE-world system generation but they hadn't called it that, and that was for their to be worlds in the two orbits beyond the habitable zone to have slightly cooler, but possible life bearing worlds within when generating system colonization.

They just never called it by that name, which is why it struck me at first glance Mal, your's was the first instance I've ever heard it labeled as such, but its a nice way of putting it.

Thanks again,

 

[Malenfant]

Middle Zone is something that has been missing from the system definitions... worlds out there are likely to be volatile rich, plus its where vaguely habitable panthalassics are likely to live (in the habitable zone they're likely to be very steamy beacuse of the greenhouse effect of their thick atmospheres, but in the middle zone they might be better).

 

[far-trader]

Cool. I kind of play with a looser definition of habitable zone to include what would be this middle zone (labeling them inner, middle, and outer zones). Now I have a better idea of where to put the huge worlds I'd like to have now and then.

So, quick question, are all panthalassics water worlds or is there a chance for some landmasses? Perhaps in a later epoch? Actually I think the site I found (see post below) may answer this question once I get into it.

 

[far-trader]

Found a cool site looking up the meaning of panthalassics

Anybody you know Mal?

The Planetary Classification List

 

[Malenfant]

I'm aware of the guy behind it, wouldn't say I know him though. But that's a good site anyway.

Definitely no landmasses on panthalassics. The actual rocky part is buried under tens of km of water and hundreds of km of high pressure ice below that.

 

[Pickles]

Originally posted by Malenfant:
eh, they can drink Slurpy-cola like everyone else

True, but MacDougal's will need water to dilute the Slurpy-cola syrup.

 

[The Shaman]

Originally posted by far-trader:
The Planetary Classification List

Spiff. Thanks for the link.