smappy wrote:…. I know very little about this topic and tbh neither do most people working on Teles, I think. I don't think any of these topics have ever been broached before let alone discussed in any detail. ….
OTOH we have had four posts about plate tectonics. So we're not really oversimplifying, IMO.
smappy wrote:Since we haven't factored any climate changes in at all I don't think the precession of the poles should be very fast because otherwise we have to redo a ton of history. Maybe a scale of 50,000 to 60,000 years would account for this. Alternatively, perhaps the Milankovich cycles are so minimal that the planet never experiences much climate change at all. A final factor is the nutation of the axes: if the planet doesn't wobble much, the Ice Age might not happen either.
Personally, I think that low change in eccentricity, slow precession of the poles, and minimal nutation of the axes would all be realistic together.
For all l know they would be realistic. (For that matter, for all I know they might not be. I admit to having more ignorance than I need.
)
But I don't think that a 26,000-year "precession of the Zodiac" is necessarily a problem with a 100,000-year history+legend (more than ten times as long as Earth's).
That'd just mean that the poles have precessed almost 4 times since the earliest historic-ish knowledge-oid.
Don't you think that'd be OK? Maybe it wouldn't.
Also, if the axis nutates just a little bit (say, 10 minutes instead of 100 minutes), I'm not sure it would be a problem for it to have made two or three (or even eight or nine) "complete nods" during the entire 100,000-year span of the project. (If I'm correctly remembering the time-span of the project?). (I don't remember how often Earth nutates, and I haven't been able to look it up recently.)
"Enough to notice" might be less than "enough to cause an Ice Age". Also, what the con-people call an "Ice Age" might not be as severe as what we Earthlings call an "Ice Age". It just means the glaciers advance further from the poles/closer to the Equator than they do at other times; how much further may depend; it may not be much further at all by Earth standards, but the people who inhabit the land they advance over and retreat from will definitely refer to "Ice Ages" or their languages' equivalent.
The less eccentric the orbit is, the less all of this matters. The distance from planet to star at periastron is almost the same as that at apastron if the eccentricity is really low. Perhaps the eccentricity varies between .09% and .11% instead of between, say, 0.5% and 1.5% (or whatever Earth's actual variation is).
Anyway, if the eccentricity changes only once every 200,000-or-so years, it can have gone between its extremes only once in the entire 100-kiloyear span of the project (again, do I have that time-span correct?).
In Earth's history before 1900, climate change has played a part. We've had the "Little Ice Age" and the "Little Climatic Optimum", and the "Fimbulwinter", and so on; the "Justinian Plague" and the "Irish Potato Famine", among other events, were due to naturally-caused climate change.
For that matter, the founding of the civilization(s) of the Nile was probably driven by a natural climate-change; at least, according to some scholars' widely-respected opinions.
Remember Earth's last Ice Age ended about 11,000 years BCE or 13,000 years BP. If the cycle on the project planet is 8 times as long as that, their last Ice Age will have ended 4,000 years before the beginning of the project's timespan
The lower the axial tilt the less effect all these things will have on the climate; so if the axial tilt is 20 degrees they'll be less strong than on Earth, where the axial tilt is (currently) 23.5 degrees IIANM.
OTOH, the higher the axial tilt the more effect all these things will have on the climate; so if the axial tilt is 30 degrees they'll be stronger than on Earth.
Similarly, lower the orbital eccentricity the less effect all these things will have on the climate; so if the eccentricity is more like 0.1% than like 1% they'll be less strong than on Earth.
OTOH, the higher the eccentricty the more effect all these things will have on the climate; so if the eccentricity is more like 10% than like 1% they'll be stronger than on Earth.
smappy wrote:And ultimately the lack of dramatic climate change could be explained by a solar system with few other planets ....
Well, you probably need at least two "gas giants" or "Jovian" or "major" planets, in order for the "rocky" planets to have stable orbits.
But if they have predictable and well-behaved orbits (say, less eccentric than Real-Life's Jupiter's and Saturn's), and are further enough from Teles's "Sun" than Teles is, and the angles between their orbital planes and Teles's is small (say, a lot less than 8 degrees -- maybe 1 degree?), then, (given I don't really know the celestial mechanics behind the Milankovich (?) variation in the Earth's eccentricity), maybe that would mean Teles's eccentricity varied less, and less rapidly, than Earth's.
smappy wrote:…. and only one small moon of Teles.
And you probably need a (relatively) big moon (satellite-mass to planet-mass ratio more like Luna to Earth and less like Phobos to Mars) to have the planet's axial tilt stay stable.
(I think it's accepted, more or less, that Mars has "flipped" -- or had major, non-periodic changes in its axial tilt -- because Phobos and Deimos aren't massive enough to help it "keep its balance".)
So Teles' single moon might be smaller than Earth's single moon, but it shouldn't be too much smaller. Unless someone (for instance, me) is wrong about something.
smappy wrote:To be honest, because the maps are all in the Mercator projection, I think the tropics might actually be farther apart than that of Earth— maybe even like 30 degrees or so! On the other hand, that would mean that the Arctic Circle would live at about 60 degrees, which seems kind of low to me, but could definitely work well. Each temperate zone would only be about 30 degrees wide but that's probably fine.
Remember, though, that if the tropic circles are 30 degrees from the equator and the polar circles are 30 degrees from the poles, that means the axial tilt must be 30 degrees. That would increase the effect of nutation, of precession, and of the variation of the planet's orbital eccentricity, on the climate of the planet.
It might be fun to have a big tropic belt 60 degrees wide, and big polar zones 30 degrees in radius, and thin temperate zones only 30 degrees wide.
You just have to remember that that co-requires a 30-degree axial tilt. That'll mean dramatic differences between summer and winter, compared to Earth, regardless of any "Milankovich variations". (As well as increased influence of these "Milankovich" parameters -- assuming, still, that I've remembered the terminology correctly.)