Detailed World Generation example, plus comments

[EvilDrGanymede]

Here's a planetary system I generated using the T20 rules, to test out the worldgen mechanics. I started from scratch (no pre-existing main world).

Stars in System: Binary (2)

Primary: Red Dwarf
Companion: Red Dwarf

I've hit some problems already here. There is no mechanism to place Companion stars, other than the suggestion on p374 that some are in close orbits around their primary (in Orbit 0), some are far (beyond orbit 20), and a few are in the planetary system. Placement seems to be totally arbitrary here - I decided to place the companion in a Far orbit.

Also, it's suggested that if a Red Dwarf is rolled then the GM can skip Step 4, which includes the bit that determines the Spectral number of the star. I ignored this, and determined that the primary was an M8 V, and the companion was an M3 V. This makes no sense - the primary star in the system should be the more massive star (the M3 V, in this case), since it's the star that the system rotates around (or if you're thinking realistically, the centre of mass of the system is nearer the more massive star than the less massive star). But I'll stick with what it says for now.

All planets are in Outer Zone for both stars since they are Red Dwarfs.

Primary (M8 V): 10 planets + 1 LGG (Orbit 6).

Companion (M3 V): PB (Orbit 0), SGG (Orbit 1), PB (Orbit 2), LGG (Orbit 3), no other planets.{/b]

- - - Main world - - -

Mainworld orbits Companion Star (M3 V)

UWP: B200410A

Mainworld is a satellite of the SGG in Orbit 1.

MW Temperature: Frozen.

I found this very confusing. Are the Temp Modifiers cumulative? Should it be +1 for being a Red Dwarf (Step 3, p372), *and* another +2 for being Type M (Step 4, p372)? Why does being in Orbit 1 give a -2 Temperature modifier (Step 1, p 374) - it's in the outer zone of a Red Dwarf!

The temperature I got (Frozen) is about right for the day side (if calculated realistically, dayside temperature should be about -60 degrees C). Night-time temperature is nonsensical as stated though: -3 x -60 is +180 degrees C. I think they really only mean for the "-" to apply if the max temperature is above 0 degrees C. If this is true, the temperature on the mainworld ranges from -60 C during the day to -180 C at night.

Of course, we don't actually have any way of knowing how long the day or night is, because there is no means provided for generating the rotational period of the world. Realistically speaking, satellites shouldn't really even exist around planets this close to their star because of tidal evolution, but that's way beyond the detail considered here.

Natural Resources Number: 4

Indigenous Lifeforms: None. As an aside, why are there no positive mods for 5, 6, or 8 atmospheres, or clement climates? It seems rather hard to find life even on perfectly habitable worlds.

Population Exponent: 3 (ERRATA: this should be a population MULTIPLIER - the number in the UWP is the exponent)

Starports/bases: Type B starport, no bases (see my other post in errata for Scout/Navy Base confusion).

Trade Classifications: Ni Va (De?).

Trade Balance: 3 (EDIT: I miscalculated this earlier)

 

[Solo]

See. It wasn't me.

The white dwarf/red dwarf spectral class "rule" drove me crazy.

Evil, how about the orbital period? How long to circle the sun/year length?

-S.

 

[EvilDrGanymede]

Discussion/comments (IMHO):

This seems a very barebones generation system, and doesn't give any clue to certain important aspects of the planet, that could easily crop up during gameplay. Notably absent is the planetary rotation rate, as well as orbital distance from the planet that the mainworld orbits in this example (there are no 'satellite orbits' tables. More importantly, there's no real link between the rotational period and the planet's temperature - longer rotation periods are going to make the daytime temperatures hotter. It could be that you're supposed to retrofit this into the Climate chart (ie. if Torrid is rolled, then the planet must have a really long day) but IMHO this is a somewhat clumsy way to do it.

There's also no mention of how to generate the size of the body if it's the satellite of another planet (e.g. a gas giant).

Another absence is the mass of the star, which allows you to determine the orbital period of the planet. Realistically, the SGG primary should complete one orbit around the M3 V primary in about 148 standard days, while the table on page 374 says that the year length is about 91 standard days.

I'm not sure what the temperature modifiers are supposed to represent. Whether a star is supergiant or red dwarf, the *size* of the star has no relevance to the temperature of the world - what's important is the *luminosity* of the star (i.e. the Spectral Type) - not the size - and the distance of the planet from the star. The latter is factored in Step 1 of the Mainworld generation, though I can't help but wonder why the info there wasn't included with the table on p373 (Step 7). So I think one solution would be to ignore the temperature mods for size, and just use the ones given for spectral type on p373.

"World Climate" on p376 is somewhat misleading - it's really describing the highest (or is it average?) temperatures reached on the world, and not saying anything at all about the actual *climate* (i.e. weather, atmospheric conditions). There's also no consideration for greenhouse effect either (particularly important for worlds with denser atmospheres) - again, it looks like you're supposed to roll up a temperature and then fudge some reason why it's like that, though dense atmospheres should surely have some negative modifier to the World Temperature roll.

It could also be made clearer that the nighttime temperatures for the Exotic and "higher" atmospheres are actually the same as the dayside temperatures because the heat is distributed throughout the atmosphere. This isn't mentioned anywhere, and may cause people to scratch their heads wondering what to do when they're staring at the "-" entry given there in the night-time temperatures.

Finally, there's very little help available in T20 for what to actually *do* with this data. It's OK for me - I'm a planetary scientist, I can easily turn a UWP into something fully fleshed out, as can anyone interested enough in astronomy - but there aren't many guidelines here for those who don't know a lot about planets to help them turn the planets they generate into something more real.

I can't think of any more points to raise here. I may be somewhat overcritical, but I think there could have been a lot more done here to make the systems more realistic, without adding too much complication.

 

[EvilDrGanymede]

Originally posted by Solo:
The white dwarf/red dwarf spectral class "rule" drove me crazy.

Note that the White Dwarf habitable zone chart on p374 is pretty nonsensical. There can be no habitable planets around White Dwarfs anyway (they're too dim, and also they'd destroy all the worlds in the closer orbits (up to Orbit 3 or 4?) around them when they're red giants anyway).

As for the orbital periods, I've just done some checking, and the multipliers shown are wrong *anyway*. I'll post the correct ones on the Errata board now.

 

[Zaron]

It looks like I was reading something wrong.
I figured the main world should be placed in the habital zone, so the main world of a red dwarf should be placed in orbit 0. Of course, that usually (more then 50% of the time) made it an asteriod belt.

Asteriod belts have an average population of over 300 million, and that's assuming the negative 2 modifier. I was surprised to see no modifier to population due to asteriod belts.

 

[Zaron]

It looks like I was reading something wrong.
I figured the main world should be placed in the habital zone, so the main world of a red dwarf should be placed in orbit 0. Of course, that usually (more then 50% of the time) made it an asteriod belt.

Asteriod belts have an average population of over 300 million, and that's assuming the negative 2 modifier. I was surprised to see no modifier to population due to asteriod belts.