CCC planet and system discussion

[احمکي ارش-ھجن]

I'm not making a culture till we are in agreement here...

Some things about a denser atmosphere:

- yes, I'd think that winds would be more sluggish
- heat will be distributed more efficiently - the poles will be warmer, the equator will be colder, nights will be warmer, days will be colder
- because of the last, there won't be as violent weather systems (which tend to stem from steep temperature differentials). There will be fewer hurricanes, and less wind in general. This will probably multiply with the first observation
- flight will be easier. Larger creatures will be able to fly, and larger creatures will be able to fly well and rapidly. Humans are likely to invent human-powered flight (which is on the edge of possibility as it is), though not for long distances
- floating in the air will be easier. In the long term that's good news for balloons, but biologically it'll also probably mean more aerial seed dispersal, which may encourage taller trees and fewer fruits
- wind resistance will be higher. Things will be slower, both airborne and on the ground
- everything other than flying will be harder. Things will have to move around less, or sleep longer, or else eat a lot more food. Herbivores can't really do much on the eating more food front, so they'll tend to be slower, which will probably mean they'll either haver to be a lot more numerous to not go extinct (if there's enough of you it doesn't matter if you get eaten a lot), or else they'll become bigger (if you're big enough, it doesn't matter if things can catch up with you). In turn, predators will tend to be bigger, but there'll be fewer endurance predators like humans and wolves, and more things will try to have long periods of idleness punctuated by brief periods of activity (i.e. ambush predators) - bad news for dogs, good news for cats. It'll also be a lot more tempting to be a scavenger. Some of the biggest carnivores will probably be scavengers (particularly since they'll probably have to compete with megacondors).

If this is the case, then I should consider that my conrace could develop flight artificial flight technology...
and would this dense atmosphere have a great impact on semi-shadow creatures?

[KathTheDragon]

Now I'm thinking about retconning wings onto the dragons. I wasn't going to give them wings, to veer away from standard dragons, but if moving around is that much harder... Alternatively, since I haven't specified what sort of magic they can do, I might say they use magic to fly, if that's not too OP.

[Torco]

Excellent point about atmospheric heat dispersal.
I think that small animals will probably be the ones more deeply affected. I mean, a 70 kilo man is probably not going to be too affected by increased air drag, even if running will become significant harder it won't likely lead to profoundly different pressures on locomotion: but bear in mind that we're pretty much macrofauna! most animals are way smaller than us. A 7 kilo dog is subject to a comparatively much stronger air drag force when moving, and I bet rabbits would find it harder to jump around <incidentally, both a 7 kilo dog running through the forest and a tiny rabbit jumping around away from it are not so very viable when everything weighs 20% more>.

water boils at 111C° under 1,5atm, incidentally. this to me suggests that less water would evaporate under those pressures, and also that a denser atmosphere is able to cope with more water dissolved in it: these two factors would lead one to believe that planetary rainfall would be less than on earth given equal isolation and so on.

Relevantly, would an atmosphere 1,5 times thicker contain, all things being equal, a lot more air, overall? and, if that be the case, wouldn't all that extra air help with greenhouse effect? and would that not, in turn, raise the temperature significantly given equal isolation? <although a thicker atmosphere would in turn have more clouds and so block more light, potentially cooling the surface: still in both cases, you get less light... plants would probably have to get darker, though.

I imagine walking around in the cold, however, would be much more unpleasant on account of having half again as much air per cubic meter to take away your heat: there's a reason why cold water is much chillier than cold air: there's just more of it in contact with your body, and more efficient heat conduction means also more efficient heat conduction from your skin to the planet... which, at 4am in the morning in Sal's continent, for example, means you're gonna have a bad time.

I suppose the atmosphere could be race-dependent in such a way that it affects each race precisely in the manner its designer chooses? joking, joking!

[Lyhoko Leaci]

- wind resistance will be higher. Things will be slower, both airborne and on the ground
- everything other than flying will be harder. Things will have to move around less, or sleep longer, or else eat a lot more food. Herbivores can't really do much on the eating more food front, so they'll tend to be slower, which will probably mean they'll either haver to be a lot more numerous to not go extinct (if there's enough of you it doesn't matter if you get eaten a lot), or else they'll become bigger (if you're big enough, it doesn't matter if things can catch up with you). In turn, predators will tend to be bigger, but there'll be fewer endurance predators like humans and wolves, and more things will try to have long periods of idleness punctuated by brief periods of activity (i.e. ambush predators) - bad news for dogs, good news for cats. It'll also be a lot more tempting to be a scavenger. Some of the biggest carnivores will probably be scavengers (particularly since they'll probably have to compete with megacondors).

The first should only be noticeable for fast things, (cars, planes, fast moving birds, maybe cheetah equivalents) and/or small things (bugs, stuff smaller than around the size of rats or so for significant effects, lesser effects for cat sized things, if noticeable at all)
The second shouldn't really be noticeable at all, the increased atmosphere is only about 50% more than Earth, it isn't a Venus type situation. And the oxygen content can be bumped a bit over Earth's to get more energy. (but will require things to eat more) Just don't overdo it so that there are a ton of fires.

And Torco's stuff:
Evaporation slows down with the partial pressure of water vapor, not total pressure, so should be just as fast as before. (The vapor pressure at 100 degrees C is 1 atmosphere, regardless of the total amount of air or water vapor floating around. When the vapor pressure is above the total pressure, things boil. When the partial pressure is below the vapor pressure, things evaporate.) At 100% humidity, the current partial pressure of water vapor is equal to the vapor pressure (at ground level) and so up in the clouds where its cooler and the vapor pressure is lower, water is condensing into could droplets, and later, raindrops.

An increased greenhouse effect would probably be the case. (The planet could be a bit farther from the sun to reduce the temperature)

Stuff would cool off (or warm up) faster, probably about at 150% the rate on Earth for a 1.5 atmosphere planet.

[finlay]

Why have such a dense atmosphere, though? Is it a natural consequence of having a bigger planet?

[Lyhoko Leaci]

Why have such a dense atmosphere, though? Is it a natural consequence of having a bigger planet?

Somewhat, though it could be reduced somewhat, say 1.2 atmospheres if the planet has 1.2 times the gravity, that way flight should be roughly as easy on Earth, and the other consequences of a denser atmosphere wouldn't be as strong.

Did you see my idea for combining the two solar systems? It kind of got buried in all the talk about the atmosphere.

[Torco]

I just wanted to say that there is a common myth that a terrestrial planet's size should be directly and rather strictly correlated with its surface such that a terrestrial larger than earth should be reasonably expected to have a denser atmosphere than a smaller one. This happens to be, I think, false: atmospheric density is a consequence of gravity on the one hand, of the amount of air around the planet on the other. Gravity *is* strongly correlated with planetary mass <actually, the one is the direct consequence of the other>, but the amount of air around a planet is entirely irrespective of planetary mass, at least within the constrained parameters of a terrestrial planet. As an example of this I submit Venus, a planet that is almost exactly as large as earth and yet has a shitload of air.

I submit that the amount of air around a terrestrial planet is a more or less contingent quantity: it is influenced by a lot of fortuitous things such as whether there have been strong solar events lately <one such even could perfectly strip the atmosphere off a planet>, the strenght of its magnetic field <in turn influenced by rotation speed, core composition, size, heat, and who knows what else>, the amount of comets and iceballs that hit it, geological activity, surface temperature, etcetera. This means that you could well have a terrestrial with twice the mass of earth <and, surprisingly enough, not terribly different surface gravity, considering> and half its surface atmospheric pressure, on account of it simply not having as much air as earth, relatively. Or having had much air but having lost it to asteroids: the key thing here seems to be to be nitrogen: oxygen is something lifeforms bind, as is carbon, and cold temperatures bind water quite easily... nitrogen, however, would act as a sort of buffer

Nitrogen is a pretty common element in the universe, but its rare in the inner solar system because it is relatively light: the amount of nitrogen a planet captures during formation seems like it would be quite fortuitous! especially if we consider that, like water, there is really not a lot of it on earth's surface: I'm not sure about the numbers, but i bet if we had only gotten two or three times as much nitrogen in this here planet we'd have a much thicker atmosphere... hell, that may have been exactly what happened to Venus: much nitrogen, huge atmosphere, huge greenhouse gas.

[interestingly, venus has proportionally less nitrogen in its atmosphere, but it has about ten times more of it in absolute terms: which is odd, if you consider that its closer to the sun and thus should have kept even less volatiles than earth did... supporting the idea that atmospheres in planetary formation are kind of unpredictable... which is ironic in light of modern meteorology, but now i'm just rambling]

[finlay]

Why have such a dense atmosphere, though? Is it a natural consequence of having a bigger planet?

Somewhat, though it could be reduced somewhat, say 1.2 atmospheres if the planet has 1.2 times the gravity, that way flight should be roughly as easy on Earth, and the other consequences of a denser atmosphere wouldn't be as strong.

Did you see my idea for combining the two solar systems? It kind of got buried in all the talk about the atmosphere.

I did (although u typoed my named five times! ). I wouldn't mind that. I like the idea of being able to see the moons of another planet. I think the main thing I disagree with you on is actually the moons. I mean mine are closely based on those of my own (stagnating) conworld but I like the idea of having ones with different sizes and brightnesses more than your one where they're both very bright and large in the sky. Everything else is sort of peripheral.

[ol bofosh]

I think by the end of the week I'm going to know more about CCCP atmospherics than culture.

[Torco]

Actually the problem is that we don't know anything about CCCP's atmosphere: if we did it'd be no problem!

[Hydroeccentricity]

If we're really committed to this idea of having different gravity, pressure, and satellites than Earth, we should probably put cultures on hold, since the biota will be greatly affected by the climate of CCCP. I would be perfectly happy just using something that's "90% Earth-like," but there seems to be a strong consensus in favor of making a non-Earth-like planet. Maybe Zompist should rename this thread "Physics Discussion" or "Climate Discussion" instead of cultures until we figure this out.

[ol bofosh]

Actually the problem is that we don't know anything about CCCP's atmosphere: if we did it'd be no problem!

I've got no problem either way, just tell the the practical implications when you're done.

If we're really committed to this idea of having different gravity, pressure, and satellites than Earth, we should probably put cultures on hold, since the biota will be greatly affected by the climate of CCCP. I would be perfectly happy just using something that's "90% Earth-like," but there seems to be a strong consensus in favor of making a non-Earth-like planet. Maybe Zompist should rename this thread "Physics Discussion" or "Climate Discussion" instead of cultures until we figure this out.

I was thinking of asking to move the atmosphere and star system posts somewhere else, and extending the culture deadline. But that would work just as well.

I've finished my golem-dragon culture. Maybe I should just leave it in drafts for the moment.

[Torco]

Well I do vote for "just like earth". Call me traditionalist, but if its good enough for all fantasy, its good enough for this fantasy

[Sakir]

Just noting that I'd prefer to keep the material parameters 'vanilla': it's tricky enough to reconcile magic without then pondering a significantly different physical setup.

[zompist]

Split out so it's easier to deal with.

[clawgrip]

I would also prefer to go with a "basically just like Earth" atmosphere, etc. The culture I invented is based on this assumption.

[zompist]

I took Lyhoko's combination proposal, with two tweaks:
-- Reduced the diameter of CCCP to 13750 km (mass = 1.26 earths), so it's not freakishly large.
-- Instead of replacing finlay's planet 10, I just moved it out further, representing all the outer dwarf planets.

Summary:

1 (F) mercurish .278 AU .0195 E
2 (L) veneroid .54 au .525 E
3 (L) veneroid .78 au .906 E - with visible moon
4 cccp 1.06 au 1.26 E
5 (L) marsish 1.63 au .246 E - with visible moon
asteroids
6 (F) saturn 6.768 au 67.254 E
7 (F) big jupiter 10.487 au 526.3 E
8 (L) uranus 15.32 au 2.781 E
9 (F) neptune 27.423 au 29.84 E
10 (L) saturn 36.46 108.096 E
11 (F) pluto 51.2 au .331 E

For moons, both agree on a moon much like ours (which has d = 3745 km). Finlay has a medium-size moon (1737 km diameter) far out, Lyhoko has a small one (d = 1070 km) closer in. I'd suggest keeping both but making the small one only half as large.

[finlay]

My planet 10 wasn't meant to be a dwarf planet! We can add some of those too maybe. Also, in order that the planets don't make such perfect circles around the sun i had an eccentricity value plugged in for each one in my spreadsheet. Maybe we could add that to your picture? (In the real world the fact that the orbits are not circular is most apparent with Mars: the sun isn't quite in the centre of Mars's orbit.)

Anyway if I have more time I will put the values back into the spreadsheet and see how visible these planets would be.

[Lyhoko Leaci]

Here's the basic visibility values I got:
one is magnitude -2.848 at max elongation.
two is magnitude -4.648 at max elongation.
three is magnitude -4.948 at max elongation.
five is magnitude -2.8 at opposition.
six is magnitude -0.4 at opposition.
seven is magnitude 0.6 at opposition.
eight is magnitude 6.6 at opposition.
nine is magnitude 7.0 at opposition.
ten is magnitude 6.7 at opposition.
eleven is magnitude 13.6 at opposition.

three's moon is magnitude -0.548 at max elongation.
moon one is magnitude -11.8 at opposition.
moon two is magnitude -13.4 at opposition.
moon three is magnitude -10.4 at opposition.
five's moon is magnitude 2.8 at opposition.

Note that I changed a couple of things, like moved the outermost moon of CCCP in a bit, as it was outside of CCCP's sphere of influence, and I reduced the size of the super-Jupiter (but not the mass) as Jupiter is more or less the largest a planet can be in volume, assuming the planet isn't a hot puffy one.

I haven't thought of eccentricity values yet.

Edit: Full data table:

Planet #1: Rocky planet; fully tidally locked Mercury-like planet
Semi-major axis: 0.278 AU
Average insolation: 14.868*Earth
Year: 0.144*Earth, 52.485 days
Local day (sunrise to sunrise): N/A
Sidereal day: 1260 hours, 52.485 days
Radius: 1732.5 km (smaller than Mercury, about the size of the Moon)
Density: 5.370 g/cm³
Mass: 0.020*Earth (1.170E23 kg)
Gravity: 0.265*Earth (2.599 m/s²)
Magnitude at greatest elongation: -2.848 (similar to Jupiter, brighter than Mercury)
Tilt: 10.1°

Planet #2: Rocky planet; fully tidally locked Venus-like planet
Semi-major axis: 0.543 AU
Average insolation: 3.897*Earth
Year: 0.392*Earth, 143.275 days
Local day (sunrise to sunrise): N/A
Sidereal day: 3509 hours, 143.275 days
Radius: 5325.4 km (slightly smaller than Venus)
Density: 4.952 g/cm³
Mass: 0.525*Earth (3.133E24 kg)
Gravity: 0.751*Earth (7.368 m/s²)
Magnitude at greatest elongation: -4.648 (slightly dimmer than Venus)
Tilt: 8.3°

Planet #3: Rocky planet; Venus-like planet
Semi-major axis: 0.778 AU
Average insolation: 1.898*Earth
Year: 0.673*Earth, 245.719 days, 80.679 local days
Local day (sunrise to sunrise): 73.095 hours
Sidereal day: 72.2 hours
Radius: 6350.6 km (Earth sized)
Density: 5.042 g/cm³
Mass: 0.906*Earth (5.409E24 kg)
Gravity: 0.912*Earth (8.946 m/s²)
Magnitude at greatest elongation: -4.948 (slightly brighter than Venus)
Tilt: 67.2°

Planet #3's moon: Rocky moon; Moon-like
Semi-major axis: 302312 km (slightly closer than the Moon)
Local day (sunrise to sunrise): 521.005 hours
Sidereal day: 479.012 hours
Lunar month: 21.657 days, 7.11 local days
Radius: 1783.1 km (very slightly larger than the moon)
Density: 3.445 g/cm³
Mass: 0.014*Earth (8.181E22 kg)
Gravity: 0.175*Earth (1.716 m/s²)
Magnitude at greatest elongation: -0.548 (Easily visible from CCCP!, similar to Saturn)
Tilt: 11.4°

Planet #4: Rocky planet; CCCP
Semi-major axis: 1.064 AU
Average insolation: 1.015*Earth
Year: 1.076*Earth, 392.990 days, 379.206 local days
Local day (sunrise to sunrise): 24.872 hours
Sidereal day: 24.807 hours
Equatorial Radius: 6875.0 km (somewhat bigger than Earth)
Polar radius: 6854.4 km
Circumference: 43196.9
Surface Area: 5.928E8 km^2
Density: 5.524 g/cm³ (slightly higher than the Earth)
Mass: 1.259*Earth (7.519E24 kg)
Gravity: 1.082*Earth (10.611 m/s²) (Only slightly higher than Earth)
Tilt: 24.2°
Atmospheric Pressure: 1.154 Earths
18% Oxygen (roughly the same as Earth when increased total pressure is taken into account)
81% Nitrogen
1% Argon
+trace other things

Moon 1: Rocky moon, smaller and closer in
Semi-major axis: 102304 km (way closer than the Moon)
Local day (sunrise to sunrise): 81.301 hours
Sidereal day: 80.607 hours
Lunar month: 3.359 days, 3.241 CCCP days
Solar year in lunar months: 116.994 months
Radius: 285.5 km (bit bigger than Vesta)
Density: 3.053 g/cm³
Mass: 0.000050*Earth (2.976E20 kg)
Gravity: 0.025*Earth (0.244 m/s²)
Magnitude at full moon: -11.8
Tilt: 2.74°
Angular size: 0.320° (0.64xMoon)
Tides: 0.67xMoon

Moon 2: Rocky moon, more like Earth's Moon
Semi-major axis: 295643 km (somewhat closer than the Moon)
Local day (sunrise to sunrise): 411.531 hours
Sidereal day: 394.371 hours
Lunar month: 16.432 days, 15.856 CCCP days
Solar year in lunar months: 23.916 months
Radius: 1636.2 km (slightly smaller than the moon)
Density: 3.394 g/cm³
Mass: 0.0104*Earth (6.227E22 kg)
Gravity: 0.158*Earth (1.552 m/s²)
Magnitude at full moon: -13.4 (somewhat brighter than the full Moon)
Tilt: 3.52°
Angular size: 0.634° (1.27xMoon)
Tides: 2.08xMoon

Moon 3: medium Rocky moon farther out
Semi-major axis: 827274 km (more than double the Moon's distance)
Local day (sunrise to sunrise): 2303.639 hours
Sidereal day: 1854.260 hours
Lunar month: 77.189 days, 74.483 CCCP days
Solar year in lunar months: 5.091 months
Radius: 868.5 km (bit bigger than Titania)
Density: 3.146 g/cm³
Mass: 0.00145*Earth (8.633E21 kg)
Gravity: 0.078*Earth (0.763 m/s²)
Magnitude at full moon: -10.4
Tilt: 1.74°
Angular size: 0.120° (0.24xMoon)
Tides: 0.20xMoon

Planet #5: Rocky planet; Mars-like planet
Semi-major axis: 1.629 AU
Average insolation: 0.433*Earth
Year: 2.038*Earth, 744.476 days, 606.736 local days
Local day (sunrise to sunrise): 29.448 hours
Sidereal day: 29.4 hours
Radius: 4253.5 km (larger than Mars)
Density: 4.563 g/cm³
Mass: 0.246*Earth (1.471E24 kg)
Gravity: 0.553*Earth (5.423 m/s²)
Magnitude at opposition: -2.8 (slightly dimmer than Mars)
Tilt: 16.3°

Planet #5's moon: Rocky moon; similar to CCCP's closer moon
Semi-major axis: 91312 km
Local day (sunrise to sunrise): 155.040 hours
Sidereal day: 153.708 hours
Lunar month: 6.458 days, 5.254 local days
Radius: 456.2 km (bit smaller than Ceres)
Density: 3.134 g/cm³
Mass: 0.000209*Earth (1.246E21 kg)
Gravity: 0.041*Earth (.399 m/s²)
Magnitude at opposition: 2.8 (visible even in an urban neighborhood, but a bit dim)
Tilt: 2.4°

*Asteroid Belt*

Planet #6: Gas giant, Saturn-like
Semi-major axis: 6.768 AU
Year: 17.261 years
Sidereal day: 9.8 hours
Radius: 46616 km (smaller than Saturn)
Density: 0.947 g/cm³
Mass: 67.284*Earth (4.018E26 kg)
Gravity: 1.258*Earth (12.334 m/s²)
Magnitude at opposition: -0.4 (similar to Saturn)
Tilt: 5.8°

Planet #7: Gas giant, Super-Jupiter
Semi-major axis: 10.487 AU
Year: 33.293 years
Sidereal day: -22 hours (retrograde rotation)
Radius: 72117 km (Jupiter sized)
Density: 2.001 g/cm³
Mass: 526.399*Earth (3.144E27 kg)
Gravity: 4.111*Earth (40.318 m/s²)
Magnitude at opposition: 0.6 (dimmer than Saturn)
Tilt: 141.1°

Planet #8: Gas dwarf
Semi-major axis: 15.321 AU
Year: 58.791 years
Sidereal day: 16.3 hours
Radius: 11432 km (twice Earth or half Neptune)
Density: 2.654 g/cm³
Mass: 2.781*Earth (1.661E25 kg)
Gravity: 0.864*Earth (8.477 m/s²)
Magnitude at opposition: 6.6 (brighter than Neptune, dimmer than Uranus)
Tilt: 15.3°

Planet #9: Ice giant, Neptune-like
Semi-major axis: 27.423 AU
Year: 140.783 years
Sidereal day: 19.6 hours
Radius: 34835 km (between Uranus and Saturn)
Density: 1.006 g/cm³
Mass: 29.826*Earth (1.781E26 kg)
Gravity: 0.998*Earth (9.791 m/s²)
Magnitude at opposition: 7.0 (brighter than Neptune, dimmer than Uranus)
Tilt: 24.9°

Planet #10: Gas giant, Saturn-like
Semi-major axis: 36.462 AU
Year: 215.844 years
Sidereal day: 10.43 hours
Radius: 54674 km (slightly smaller than Saturn)
Density: 0.943 g/cm³
Mass: 108.096*Earth (6.456E26 kg)
Gravity: 1.469*Earth (14.405 m/s²)
Magnitude at opposition: 6.7 (brighter than Neptune, dimmer than Uranus)
Tilt: 42.5°

Planet #11: Venus-sized Pluto
Semi-major axis: 51.243 AU
Year: 359.609 years
Sidereal day: 29.6 hours
Radius: 4937.2 km (between Venus and Mars)
Density: 3.924 g/cm³
Mass: 0.331*Earth (1.978E24 kg)
Gravity: 0.552*Earth (5.413 m/s²)
Magnitude at opposition: 13.6 (about as bright as Pluto)
Tilt: 15.3°

~Kuiper belt equivalent~

I think everything's correct or nearly so.

I think the super-Jupiter might have been formed by the collision of two gas giants, to explain why it has such an odd rotation angle... Which probably means it also has a messed up moon system as well.

Edit: Comparisons of radius and brightness added/fixed, actual data remained unchanged.

[Lyhoko Leaci]

I've been thinking about the tipped over super Jupiter planet, would it be okay if I gave it a gas dwarf moon (roughly Earth-mass) that originated in a collision between two gas giants that caused the super Jupiter to tip over to begin with? Such a moon would be quite dim, but slightly brighter than Uranus, so it could possibly be seen, assuming the light from the super Jupiter itself doesn't drown it out. (They would appear very close together in the sky)

[zompist]

No one's objected, so you'd might as well go through with it.

How much of an angle of separation would you get, from CCCP?

[Lyhoko Leaci]

About 2.9 arc minutes at max, assuming the moon has an orbital radius of around 1,200,000km. (slightly farther than Ganymede is from Jupiter)
The moon would have a magnitude of about 5, while the planet has a magnitude of 0.6.

[zompist]

OK... based on this page, that would be quite difficult to separate by eye, even without the brightness variation. For human eyes, 5 arc-minutes is hard.

Of course, not everyone on CCCP has human eyes.

[KathTheDragon]

I'm tempted to give the dragon species super-vision, so that they'd be able to pick out such details in the heavens. Probably also the fainter stars, so their star-maps would possibly be the most detailed of all organics.

[Lyhoko Leaci]

I made a sort of star map by taking pictures of the sky from the CCCP in Celestia, though right now I'm not entirely sure how to post them. There's 40 pictures in total, each being a set of one with just the stars (and planets) and the other with an overlay of a grid. The brightest star in the sky is Alpha Coronae Borealis, with an apparent magnitude of -1.48. The closest star is 4.31 light years away, but doesn't have a specific name, just a couple identification codes like "HD 146641" and "TYC 2046-402-1".