[Space] Adapting to long days and other implications of a generated system

[David Johnston2]

Originally Posted by StevenH

Since the worlds are orbiting each other, there will be a Long Night (approx 48 hours) and a Short Night (around maybe 10 hours?) caused by the daily eclipses by its companion. .

Eclipses don't last that long. It wouldn't really be all that difficult over a couple of thousand years for humans to adopt a 32 hour awake/16 hour asleep cycle, maybe with a nap in the middle. Of course most of the time the night will be fairly well lit what with the giant moon and the close stellar companion. In fact the moon will be reflecting so much light that there would probably be noticeably less difference between day and night temperatures.

As for the very thin atmosphere, it would be...difficult to colonise it without actively modifying humans to fit using something like magic biotech. Just about impossible. It doesn't help that 80% hydrosphere means their sea level is comparitively high. On the other hand if somewhere in there they have a super-Grand Canyon, something that goes really really deep at the bottom they might get up to Thin Atmosphere there. But I can't imagine how to keep it from filling up with water.

[Diomedes]

Originally Posted by David Johnston2

It doesn't help that 80% hydrosphere means their sea level is comparitively high.

Actually, if the two planets are tidally locked, each planet will have a permanent tidal bulge facing its twin, and another on the far side, with relatively shallow seas in between.

[Agemegos]

Originally Posted by Diomedes

Actually, if the two planets are tidally locked, each planet will have a permanent tidal bulge facing its twin, and another on the far side, with relatively shallow seas in between.

Nope. The water in the oceans will conform to the tidal bulge for the same reason the bulk of the planet does. You do recall that sea water is affected by the tides, don't you?

So the planets will be somewhat prolate (elongated) with their axes pointing at each other. But the pattern of land and water will be spread out all over their surfaces.

[CattyNebulart]

Originally Posted by Dagger of Lath

This star is 1 tenth as bright as the sun and 3 to 9 times further away. The brightness decreases by the inverse square law so it will be 90 to 810 times less bright than the sun.

The star will be barely noticeable in my opinion, though I haven't had enough time to figure out the full maths. (If I get the time I'll figure it out exactly for you).

the sun gives on average about 50'000 lux, divide by 1000, 50 lux is around the light in the family living room.

I'd say that's noticable alright.

[Agemegos]

Originally Posted by Indigar

Also, how hard would it be for normal humans to adapt to the 98-hour (four-DAY) days on such a world? Humans would have arrived on this world from Earth in a Banestormish way about 2000 years ago.
How well would humans arriving from modern Earth be able to adapt?

Well, they'd need a siesta in the day and a waking period in the night. Or they can arrange a cycle with four sleeps per day. That's not a problem.

You have a bigger problem with daily temperature variation. The days will warm up more, and the nights cool down more. This will be uncomfortable to animal, dangerous to plants, and will drive strong diurnal winds (onshore and anabatic during the day, offshore and catabatic during the night). On the other hand slow rotation means low Coriolis forces, so cyclonic winds will be weaker.

Speaking of plants, the long day-night cycle will challenge the physiology of plants from Earth. The light half and the dark half of their respiratory cycle are adapted to a twelve-hour duration. I don't know how much trouble this will be.

Summary: in his classic Habitable Planets for Man, Stephen Dole assumed that the upper limit on the daylength for habitability by Man was 96 hours, because of diurnal temperature variation killing plants.

Incidentally, don't forget that because each planet is tide-locked to the other, each is in synchronous orbit about the other. That means that, seen from each planet the other holds a fixed position in the sky. That means that it is visible (always in the same place) from one half, and is never visible from the other.

[Anaraxes]

The inhabitants of one side of the planet have a pantheon of wandering gods associated with the visible planets, while dismissing as ludricrous heathen myth rumors of the monotheistic religion of the antipodes between the pair, with their one all-powerful god with a few attendants.

[Lord Carnifex]

I dimly recall a psych study involving locking a test subject in a habitat that lacked clocks or other discrete time measures. The subject was encouraged to follow whatever cycle was comfortable, with the aim of extending it if possible. I believe that they found subjects could adapt in time to a 32-hour awake, 16-hour asleep cycle.

In this situation, it sounds like the secondary is going to be a significant source of light, anyway. So probably the inhabitants of the system will develop thick window shades and a complex mechanism for charting time based on the movements of the primary, the secondary, and their eclipses by the partner. Day and night cycles may either become relatively meaningless or a source of religious ritual and mystic belief.

I don't imagine, even with a high partial pressure of O2 that the companion planet is going to be comfortable for long-term human habitation without significant magical or technological help. But I'm not sure that this is a bad thing. Maybe the companion is the home of the sorcerous elite, ruling over the lesser mundanes. Or maybe the companion is a place rarely or never visited, a location of myth and wonder. Ever since the Great Exodus, no one has gone there and lived to tell about it...