Celestia Forums

Why are all tidelocked habitable planets in OA hab. only in "twilight" region ..?
There were some computer simulation that there will be a hot 63 deg. huricane on dayside if the Earth was tidelocked but water oceans will extend to dayside and also to a portion of nightside because ocean water
freezes at -21 deg.
So why is the day region on these planets instead of hot tropical hurricane covered in dry sand and night region all frozen?

What is the assumed avg. temperature for Twilight and Dante in OA?

m1omg,

Your question probably is best asked on one of the Orion's Arm mailing lists. it is, after all, a science fiction scenario. Although it was intended to be as plausable as possible, some of its planetary physics may be a little out of date.

But one of the authors of the Celestia OA Addons may have another viewpoint

Steve can probably answer better, and more to the point than I, but I'll have a go...

Basically, I think some of those Vesperian worlds were designed back before some of the more serious notions of habitable worlds in orbit of cool stars were in the mainstream. Thus, good science on them was hard to find in the literature. It seemed logical to assume that on a world where the sunward side was scorchingly hot and the dark side was freezing cold, the twilight regions would be the most habitable.

In my own setting, I have delineated various different gradiations of such worlds, ranging from the OA-type (which, by the way, I don't think are the only such type in OA), on through to more and more lush worlds with thicker atmospheres.

Anyway, that's a quick answer. But like I said, Steve Bowers (whio is my senior in terms of being a member of OA) may have a somewhat more accurate and insightful answer. In the meantime, the link to join up with the OA mailing list is:

http://groups.yahoo.com/group/orions_arm/

You need to be approved for membership, so be certain to write a little bit regarding why you'd like to join (a sentence or two would be fine). That way, we can be sure you aren't a spam 'bot!

...John...

Thanks , I will soon become a member!

Actually, John, I think you were at OA before me, by several months.

I haven't has much time for worldbuilding recently, being mostly concerned with illustrating and updating the site and writing the Starlark serial (part II coming soon!)

Twilight worlds would be more likely at the outer edge of the habitable zone, on planets with fairly thin atmospheres. Planets with thicker atmospheres would have much more circulation of air, heat and water vapour, so could easily have larger zones which could support life. But a planet with a thicker atmosphere would not be very habitable for unmodified humans (not generally a problem in OA).

Two real problems on tidelocked worlds are atmospheric collapse, which might occur at the edge (the air freezing on the dark side) which might happen on planets on the outer edge of the habitable zone, and superrotation of the atmosphere, leading to very high winds.

Some links on tidelocked planets;
http://en.wikipedia.org/wiki/Aurelia_an ... on#Aurelia
http://www.treitel.org/Richard/rass/tidelocked.html
http://www.treitel.org/Richard/rass/tidelock01.txt

and the circulation on this model of a tidelocked giant planet is beautiful.
PDF

eburacum45 wrote:Actually, John, I think you were at OA before me, by several months.

I haven't has much time for worldbuilding recently, being mostly concerned with illustrating and updating the site and writing the Starlark serial (part II coming soon!)

Twilight worlds would be more likely at the outer edge of the habitable zone, on planets with fairly thin atmospheres. Planets with thicker atmospheres would have much more circulation of air, heat and water vapour, so could easily have larger zones which could support life. But a planet with a thicker atmosphere would not be very habitable for unmodified humans (not generally a problem in OA).

Two real problems on tidelocked worlds are atmospheric collapse, which might occur at the edge (the air freezing on the dark side) which might happen on planets on the outer edge of the habitable zone, and superrotation of the atmosphere, leading to very high winds.

Some links on tidelocked planets;
http://en.wikipedia.org/wiki/Aurelia_an ... on#Aurelia
http://www.treitel.org/Richard/rass/tidelocked.html
http://www.treitel.org/Richard/rass/tidelock01.txt

and the circulation on this model of a tidelocked giant planet is beautiful.
PDF

Well, Aurelia has Earthlike air and water even on its dayside, trough conditions are best at twilight zone.
And thick atmosphere... I guess that human can withstand fairly high pressure with the right quantities of O2 avilable but too much O2 or N2 is not good...some filters and pressure suit may be necessary if there is too much N2 or O2 but if the buffer gas is an inert gas that is not narcotic than zou can well survive very high pressure..otherwise deep diving would not be possible.
And what about a superterrestrial on the outer edge with a high volcanism?Like Gliese 581 d.