Gliese 581g - A Tidally Locked DnD World

[Umbran]

How about creatures (perhaps intelligent) born on the central band which have now adjusted to both extremes. They spend time basking in the sun of the hot side, and then go on hunting trips in the cold side (perhaps because they find the hot side creatures inedible for some reason).

Well, it isn't like there's this terminator line, and on one side of it it is bright hot sun, and just a few feet away it is dark and cold. In a planet with an atmosphere, there's a broad band - full-sun shades to twilight shades to dusk shades to full-night, over the course not of feet, but of tens or hundreds of miles. The temperature will have a similar gradient.

So, if there's an animal that does what you suggest, it probably isn't doing it as a short hop, but as a major journey - go to feed on the night side, come back to breed on the day side, or suchlike.

Which brings me to another note - unless there's a major moon or other body that drives a periodic change, this planet does not have "seasons", as we understand them. The climate would have weather, but otherwise be "steady state" over the course of the year.

 

[jonesy]

Well, it isn't like there's this terminator line...

So, if there's an animal that does what you suggest, it probably isn't doing it as a short hop, but as a major journey - go to feed on the night side, come back to breed on the day side, or suchlike.

If it's a magical world there could be.

But now I'm thinking that the idea of a race which spends its entire life on the move crisscrossing between the sides is actually pretty neat. Maybe three months (how would you measure time on a world like this?) resting, breeding, and generally taking it easy on hot side, then off to another long trek through the cold.

 

[wolff96]

I think the more interesting idea is not that the planet *stopped* spinning, as someone mentioned, but that it's always been that way.

Creatures native to the world are used to this situation. Outsiders could be drawn to this world because of it's unusual properties.

I'm thinking (off the top of my head):
An Outpost of the City of Brass, almost right in the middle of the sun-side.
At least one undead (vampiric, probably) city on the night-side, enjoying the perpetual darkness.
Nomad elves, wandering from the dark-side to the light-side and trading with each -- furs and firey items to the cold-side, blocks of ice (via sled or magic) to the communities close to the temperate band.
The location on the planet reflecting the power of the gods -- clerics of Pelor, for instance, face significant penalties on the dark-side. (Brings a whole new meaning to 'being a shining light in the darkness').

I could see this as a world where non-magical flight was relatively common, given the winds mentioned above -- hang-gliders, hot-air balloons, and the like would be very efficient means of travel, depending on where one wanted to travel.

 

[Thornir Alekeg]

If it's a magical world there could be.

But now I'm thinking that the idea of a race which spends its entire life on the move crisscrossing between the sides is actually pretty neat. Maybe three months (how would you measure time on a world like this?) resting, breeding, and generally taking it easy on hot side, then off to another long trek through the cold.

i was thinking about a race that establishes most of the society in the habitable band. They can absorb and store energy from the sun. In the habitable band there is enough energy to sustain them, but not enough for propogation of the species. Adults travel to the bright side where they store up energy and mate with each other.

Unfortunately newborn offspring are highly sensitive to the radiation from the sun, so after mating, adults travel to the dark side of the planet to bear their young and raise them until they are old enough to handle the normal radiation present in the habitable band. Because of the dark and cold conditions, the energy stored from the bright side is essential to the survival of the parents.

The journey from the dark side to the habitable band with their young children is the most dangerous part of their life cycle as the parents are low on stored energy and the children have few skills to survive on their own without their parents. In the habitable zone when new families start to arrive it is a time of celebration, followed by a period of mourning those who did nto survive the journey home.

 

[Desdichado]

Here's one example, from Leigh Brackett.

 

[Someone]

Which brings me to another note - unless there's a major moon or other body that drives a periodic change, this planet does not have "seasons", as we understand them. The climate would have weather, but otherwise be "steady state" over the course of the year.

Excuse me for the non-accurate terminology, but if the planet's rotation axis isn't perpendicular to the plane of the orbit, wouldn't the terminator vary with the "season"?

 

[Alisair Longreach]

What if Athas is small, tidally locked world orbiting a small red star. The Tablelands is just below the terminator towards the day side, having an eternal day but still habitable. To the south the land gets more scorched and hostile to life. To the north the land gets more green and cooler and the light gradually turns to dusk until you reach the frozen wastelands shrouded in eternal night.

 

[Festivus]

Excuse me for the non-accurate terminology, but if the planet's rotation axis isn't perpendicular to the plane of the orbit, wouldn't the terminator vary with the "season"?

And does the world have to be spherical? What about a torus shaped world that was in geostationary orbit around a red dwarf sun, but that rolled, rather like a wheel. You would have differing gravities as well as environments. Perhaps the outside of the wheel being more like that of the moon, and the inside being that of two earths.

In the original example, I imagined it might have a slight warble to this rotation, giving you the dusk/dawn effect in the central belt.

 

[Umbran]

Excuse me for the non-accurate terminology, but if the planet's rotation axis isn't perpendicular to the plane of the orbit, wouldn't the terminator vary with the "season"?

The process of becoming tidally locked will generally force the axis of rotation to be perpendicular to the plane of the orbit. You can have some small wobble, but nothing like the 23.5 degrees Earth has.

And does the world have to be spherical?

Actually, it won't be, in general. A tidally locked body will be elongated - with a long axis along the line between the centers of the bodies. So, like an egg, one end pointed at the star.

What about a torus shaped world that was in geostationary orbit around a red dwarf sun, but that rolled, rather like a wheel.

Well, now you're talking about a shape that couldn't develop by real-world natural processes. Magic is involved, so all bets are off!

 

[Stormonu]

"Dark side" would probably have a wide variety of bioluminescant plant/animal life.