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Comment by rezashirazian | Hacker News Reader

This is the first time I'm reading about this concept and I find it fascinating. If there was to be intelligent life on an eye ball like planet the cultural, mythological and theological aspects of having a thin habitable strip of land sandwiched between ice and fire would be captivating.

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He was told that when approached the light would swiftly ascend to scorch him. Like the others, he was told to stay in the narrows, where both the light and the cold darkness were at a safe distance, but he set out on foot anyway. When he first encountered the Anteriorkies, Perimetus knew his defiance had paid off, and the Anteriorky leader gave Perimetus shelter from the angry light above...

What are you quoting?

It's Mangeletti.

This would pull me into the rest of the book. You just feed me images and a whole story to imagine. Thanks a lot.

I don't know any published books that use this as a trope, but it's a popular writing prompt on reddit: https://www.reddit.com/r/WritingPrompts/search?q=tidally&res...

This was a good one: https://www.reddit.com/r/WritingPrompts/comments/35mgnn/wp_a...

A similar concept was used in Jack of Shadows by Roger Zelazny, but with fantasy elements.

https://www.amazon.com/Shadows-Rediscovered-Classics-Roger-Z...

I'm imaging an age of discovery-esque expeditions to the center of the Solar Plane.

They'd likely have radically different definitions of poles. One hot enough to melt lead, one cold enough to freeze C02.

> They'd likely have radically different definitions of poles. One hot enough to melt lead, one cold enough to freeze C02.

Well, in a certain sense the West Pole and East Pole would exist in the manner you describe, but the behavior is not similar to that of the north and south poles. The stars will still rotate around the north-south axis, and east-west still won't affect that. It's not obvious that both phenomena should be called "poles".

> The stars will still rotate around the north-south axis, and east-west still won't affect that. It's not obvious that both phenomena should be called "poles".

Note that "north - south" poles already refers to two distinct phenomena, the axis of rotation and the axis of the magnetic field (these happen to be closely-enough aligned on Earth that the latter has historically been used as a proxy for the former, though this is by no means a universal feature of all planets.) The axis of orientation to the sun, for a tidelocked planet, seems no less plausibly described as "poles".

North and south magnetic poles are named after the north and south celestial poles because they seem to coincide. That doesn't apply to the solar poles.

People always make use of local geographic features when describing directions; river communities use "upstream" and "downstream" and island communities use "inland" (away from the sea). Those aren't termed poles (even though "inland" is defined by reference to a line perpendicular to the ground!), and while I agree that the axis of orientation to the sun is more pole-like than they are, it's still different enough that I don't see that it would necessarily be referred to in the same terms.

> North and south magnetic poles are named after the north and south celestial poles because they seem to coincide.

Sure, and that's why the axis-to-the-star probably wouldn't define "north" and "south" poles, but not a reason it doesn't make sense to call that the points where the surface intersects that axis through the planet "poles".

That all depends on how some not-particularly-advanced people feel about it when the terms are determined.

Having thought a bit more, I tend to think it's unlikely that both axes would be significant to the same people (and therefore that they are particularly unlikely to share terminology):

- One important aspect of east-west historically is that east is sunrise and west is sunset. This wouldn't matter to anyone on Tidelocked World, but it corresponds pretty well to the idea of having a Day Pole and a Night Pole. The Day Pole would be apparent to anyone who lived in an area where the sun was visible, and the Night Pole would be totally unapparent to everyone else; it is significant only in that the Day Pole is on the opposite side of the world.

- Historically, north is cold and south is hot. This would apply, I believe, only to the day side of Tidelocked World. It reinforces the idea of a Day Pole while doing nothing for the Night Pole (everything beyond the terminator should (?) be equally cold).

- North and south are also defined by reference to the stars, which rotate around the polar axis (this is the origin of the word "pole", and would definitively rule out a Sun Pole if "poles" had to be defined that way, which they don't). This would be apparent to everyone living in the night, but probably not to anyone in the day.

If you believe all that, then we have the sun as a navigational aid that guides us toward the hottest part of the world, and the stars as a navigational aid to indicate the North and South Poles, but no concept of a Night Pole, because that concept is useless on the night side and there are no local indicators for where it is. Day people would be likely to refer to "sunward" and "darkward" in the manner of islanders, and night people would likely refer to "north" and "south", but day people would be unlikely to recognize "north" and "south", and night people would be unlikely to recognize "lightward".

>everything beyond the terminator should (?) be equally cold

I don't think so. Winds, diffusion, conduction, refraction probably come into play.

Sure. How much variation do you expect as a function of distance from the terminator? Other sources of variation aren't really relevant.

It does occur to me that the Night Pole might be revealed by the shadow of the planet, if it has a moon.

You don't have to look to rural tribes to find this behavior. In Manhattan, "North" and "South" usually are colloquially defined with respect to the orientation of the island, not the actual compass directions.

And here in the vicinity of Santa Cruz, and going up towards San Francisco, "north" and "south" are often defined by reference to the labels on a freeway, even when that freeway in fact runs east-west.

Doing that in the Bay Area can have some odd results, as (for example) there is a stretch of freeway that is simultaneously I-580W and I-80E (and vice versa). Naturally, it runs almost due North and South.

Check out Proxima by Stephen Baxter:

https://www.amazon.com/Proxima-Stephen-Baxter/dp/045146771X

It's a Sci-fi book about life on Proxima Centauri and includes the idea you mentioned.

(Also a really good read!)

God damn it!

I have this annoying habit of impulsively buying books recommended on HN. Never been disappointed by one though. So thanks! :).

Until the 20th century, no human had been on either pole of Earth either.

But differences of temperature between Earth poles temperatures and those temperature differences in tidal-locked planets is much smaller

We haven't explored the bottoms of the oceans very well yet.

So that'd be more advanced than us I think.

> They'd likely have radically different definitions of poles. One hot enough to melt lead, one cold enough to freeze C02.

Think of the industrial applications! You'd have early metalworks near the hot pole, and when they'd finally figure out thermodynamics, I could imagine a planetary thermal engine created by bridging the hot and cold areas...

You could pretty easily imagine a planetary thermal engine on earth as well though - between the poles and the equator. In fact, we do have one. It's called "weather".

Who says they have poles? Maybe they only have austrians and hungarians.

A Polandball planet would definitely have poles.

A song of fire and ice perhaps? That might explain their strange seasons.

There is an alternative explanation for their off seasons proposed in this April fools arxiv paper

http://arxiv.org/abs/1304.0445

The Three-Body Problem by Liu Cixin features a more extreme version.

https://www.goodreads.com/book/show/20518872-the-three-body-...

Also check out https://en.wikipedia.org/wiki/Rocheworld

Hard to imagine it being habitable when simple weather patterns would expose the thin strip to both extremes.

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