Celestia Forums

I think its an interesting type of planet so why there is almost no detail on it, in Celestia with OA addon and even on the web?I visited some PelaVenusian world , with name some thing like Whrenwood, Whirldwood, or what and that planet was just enshrouded in white clouds and also I couldnt view surfaces of OA planets when I uncheck the Atmosphere and Clouds in settings the clouds and atmosphere are still there!Any hints?

Also, where I find some more information on PelaVenusian subtype and planet classification in general (OA)?

Thank you for answers.

...Michal...

The OA planet classification system is here: http://www.orionsarm.com/science/Non-lu ... tions.html

It is based off of an older version of my Planetary Classification List, located here: http://arcbuilder.home.bresnan.net/PCLMaster.html

Both lists are incomplete, as far as entries *and* data goes, so you'll just have to be patient.

The PelaVenusian world type is a much older holdover, however, and would probably be best fit by the Pelagic world type for OA, or the BathyPelagic Subtype from my PCL.

Steve, if you're reading this, we should probably look into finalizing that list for OA.

...John...

I doubt that we will ever finalise it, as new data and potential planet types are being suggested all the time. For instance Gliese 581c and Gliese 581d are both interesting planet types which are not easily fitted into the range we have described so far; how would you decribe them best?

Yeah, good point.

But what I meant was, we should finalize or refine what we have, and then we can add new types as the discoveries conitnue to roll in. I don't know; the page seems somehow incomplete to me... but then, I may just be picky.

I just learned that there is even XeroVenusian subtype here, in the Zete Reticuli and YTS 2145-098-3 (both are terraformed now).What about this type?

eburacum45 wrote:I doubt that we will ever finalise it, as new data and potential planet types are being suggested all the time. For instance Gliese 581c and Gliese 581d are both interesting planet types which are not easily fitted into the range we have described so far; how would you decribe them best?

I belive that the perupetual night side somewhat cools the Gliese 581 c planet so maybe BathyVesperian subtype.

Suggestion that c planet is extremely hot and having supercritical ocean is imho premature and it did not take the tidal lock into account.
And various chemical cycles on that planet will almost certainly not be Earthlike so, yes, that there was written in one paper that with Earthlike cycles Gl 581 c will be not habitable, but we don't know anything about these cycles and assuming that Gliese 581 d has a 5 bar CO2 atmosphere is naive because the normal planetary atmospheres ussually do not consist from one kind of gas.

Or maybe the oceans will condense on the night side where there is relatively temperate 37 deg. Celsius and the biosphere will get oxygen from skyplankton phosynthesis in the temperate upper atmosphere on the dayside.

Where is your source for the 37 degree temperature on the nightside?

If you consider the analysis leading to a determination of non-habitability premature, surely the claims of being able to support Earthlike conditions are even more so, given the quick-and-dirty temperature estimate used would peg Earth as a frozen iceball!

I will also point out that Venus has no problems maintaining hellishly high surface temperatures on its night side. Ok, it isn't actually tidally-locked, but the rotation is very slow, which should give the nightside loads of time to cool down, no?

chaos syndrome wrote:Where is your source for the 37 degree temperature on the nightside?

If you consider the analysis leading to a determination of non-habitability premature, surely the claims of being able to support Earthlike conditions are even more so, given the quick-and-dirty temperature estimate used would peg Earth as a frozen iceball!

I will also point out that Venus has no problems maintaining hellishly high surface temperatures on its night side. Ok, it isn't actually tidally-locked, but the rotation is very slow, which should give the nightside loads of time to cool down, no?

But Venus's rotation was reversed AFTER the runaway greenhouse because of friction that planet is tidelocked from beggining and that hellish atmosphere is so thick that it transfer heat perfectly.
http://www.exoplaneten.de mentions that with an Earthlike atmosphere there is only 40 deg. temperature difference between night and day side so I calculated aassuming an greenhouse effect +35 deg. Celsius so the dayside is 77 deg. hot.

Why volatiles like water will create runaway greenhouse if they could condense on the nightside?
Venus was not born with hellish atmosphere.
If the Venus was tidelocked from the beggining, it will be saved.
Your arguments are all flawed.

m1omg wrote:But Venus's rotation was reversed AFTER the runaway greenhouse because of friction that planet is tidelocked from beggining and that hellish atmosphere is so thick that it transfer heat perfectly.
http://www.exoplaneten.de mentions that with an Earthlike atmosphere there is only 40 deg. temperature difference between night and day side so I calculated aassuming an greenhouse effect +35 deg. Celsius so the dayside is 77 deg. hot.

Why volatiles like water will create runaway greenhouse if they could condense on the nightside?
Venus was not born with hellish atmosphere.
If the Venus was tidelocked from the beggining, it will be saved.
Your arguments are all flawed.

That is not entirely certain. There is a new theory that Venus, early in its history, like Earth, was struck by one, possibly two large planetesimals (http://www.sciam.com/article.cfm?articl ... 414B7F0000) While a long way from being proven, it is far more plausible that atmospheric tidal friction, which while having an effect indeed, would presumably take far longer to achive than Venus has been around.

Regardless of whether this theory is correct or not, however, the atmosphere tidal friction theory is also *far* from certain, and has just as much uncertainty. Also, we do *not* know whether or not Venus, or the Earth for that matter, formed with a hellish atmosphere. Certainly both worlds would have had thick atmospheres of CO2, methane. It may be that the oblique impact of Theia, which formed our Moon, depleted much of that primal atmosphere, making room for a much more volatile-rich one. We simply don't know.

Actually, in the paper analysing the habitability of the planets, tidal locking is taken into account, so that doesn't get you off the hook!

Furthermore, even if the volatiles did condense over the dark side of the planet, what's to stop more volatiles from evaporating on the day side and replenishing the atmosphere? At 77 degrees C you'd get a lot of evaporation going on! It seems likely that volatiles make up a substantial fraction of these planets' masses (note also that the transiting planet of Gliese 436, which has similar mass and orbit to the innermost planet of Gliese 581, seems to be mainly icy). This would naturally lead to a situation where a volatile-rich, greenhouse atmosphere builds up on the planet, at which point a highly-insolated planet such as Gliese 581 c gets in trouble.

Ok, but so what kind of planet may be Gliese 581 c and d?

m1omg wrote:Ok, but so what kind of planet may be Gliese 581 c and d?

The quick and easy answer: unique planets. The more complicated answer: they are unique planets

Despite the planetary classification schemes for OA and ArcBuilders, I have a distinct feeling that planets will forever fail to agree to be neatly placed in anything but the most general of categories. We know so little about planetary evolution, it is not hard to think that even small solar environmental factors, small differences in planetary composition and size and mass, all of this could lead to large differences in the end result.

I'm willing to bet that, whatever conditions we image to exist on those planets, the truth will end up being far different.

...John...