Open question

[james_davis_nicoll]

Assume a habitable world: what arrangement of stellar system, planetary system arrangement, orbital eccentricity, obliquity and/or other factors would you say would give the most amusingly varied climate?

Comments

[onyxlynx]

And by "amusingly varied climate," you mean "wonderful for a fraction of the year, and completely disastrous for the rest of the time," no?

[autopope.livejournal.com]

Picture a triple star system. The primary for our habitable planet is a stable G-type dwarf, but for shits and giggles the distant secondary -- which the primary orbits on a highly eccentric eliptical orbit -- is a Wolf-Rayet star. Meanwhile, there's a pulsar about a quarter light year away (vaguely gravitationally bound to the other two stars) that occasionally tips a shit-storm of comets in from the Oort cloud(s).

Our habitable planet is more or less tidally locked to a moon the size of Mars, at less than the remove of our moon (so it has melonfarming big tides) and there's another moon, about Luna's size, at half the distance, in a 3:2 resonance with Big-Ass Moon. Oh, and our habitable planet has a rotational axis at 30 degrees off-kilter from the plane in which its moons orbit. Conning a clipper ship is hard work.

We have the potential for simultaneous double solar eclipses combined with insane tidal surges.

[jeriendhal.livejournal.com]

Welcome to Pyrrus 5, or its kissing cousin.

[monte davis (from livejournal.com)]

Sweet! With those moons, earth tides should be enough to kick up some seismic fun too.

We're fortunate you're just a demiurge and not The Real Thing.

[nebogipfel.livejournal.com]

Tidal friction & regular comet showers - this planet actually could stay habitable longer than Earth. Tidal forces may produce enough heat to keep tectonics going (wild guess, I admit). Comets provide volatiles. A bit like Io with regular showers.

[krfsm.livejournal.com]

The WR star would kill it way before it became lifebearing, I think...

[peter-erwin.livejournal.com]

Yes, the WR star will unfortunately go supernova in a few million years...

(Which means it would be gone before the G dwarf has reached the main sequence and its planets have finished forming.)

[anzhalyumitethe.livejournal.com]

Imagine a world that is tidally locked to a K class star. The warmth is sufficient to keep the day side warm and habitable. The far side has an Antarctic cold trap. There are massive glaciers on that side, even so much so that the cold pole has almost a perpetual ice age. The warm side does have a mild derth of water compared to Earth. Normally that is.

The warm side has greatly increased evaporation near the warm pole, but the water does precipitate out for the most part before reaching the cold trap. However, just from humidity and the crepuscular oceans, the moisture gets locked in the cold pole bit by bit.

There are continents like on earth, if smaller and more fragmented, but...the cold trap has trapped enough of the water that the oceans are far below the continental shelves. Continental drift is slower than on Earth due to the water being locked up. The continental shields are drier than the shelves, but not uniformly desert. The shelves have the greatest biodiversity.

The oceans stretch like fingers towards the warm pole, but don't /quite/ reach it due to the evaporation increase. There is something close to a ring of ocean, the Ocean Styx, at the ring warm/cold equator.

This would be slow death to the world, mitigated by the occasional warming through belching volcanoes.

However...

The K dwarf is in orbit around a G class star. Its a pretty eccentric orbit, too. Every ten thousand years, the K star swings close enough for a couple centuries to cause massive warming to the world. This causes a swing in temperature on the cold side above freezing at the cold pole. This causes massive melting.

And you get Noachian floods on the warm side. Never enough that it inundates the continents proper, but the shelves and warm pole is submerged. There's a huge injection of water into the faults and whatnot on the warm side...earth quakes happen during and after the floods. Wild hurricane storms while the warm pole dries out over the next few thousand years. The continents become biologically isolated while wetter and more productive. The result is that we see something of a world of the Amazon: isolated pockets of life that crash together and then separate on a regular basis, something like what has happened to the Amazon itself. Between the inundations, the shelves are filled with a diversity of life that was only seen in the tropics here on earth...

[(Anonymous)]

Depends on what you mean by amusing. With an obliquity of, say, 70 degrees, the poles in summer get far more insolation than the equator does today. One paper I reviewed had the northern seas boiling in July. They were naturally pushing the model well beyond it's domain of validity, but it would nonetheless get rather hot.

In Southern Ontario we would experience 24 hour daylight for some months (1), with two temperature maxima, perhaps June and August, followed by a few months with a day/night cycle before the sun sets for a few months in winter. If phase lags are strong enough there might be an amusing period in, say, November, when the sun never rises, yet it's still quite warm.

We can modify this with eccentricity and the time of perihelion. If we go for a huge eccentricity and aphelion sometime in July, we can have all the sun we want without extreme heat - but then the southern hemisphere's summer will be hot enough that water probably will boil, so that scenario self destructs.

In SF there is Tony Rothman's one novel, focusing on a planet with a day which is a large fraction of the year, and Aldiss' "Helliconia" books, set in a long period binary system.

(1) Being vague as I'm too lazy to work out the actual time.

William Hyde

[hattifattener]

You have a close-in, Jupiter-sized object in the habitable zone, and an Earthlike planet in a horseshoe co-orbit. Every hundred years or so it would make an approach to the Jovian, there would be massive tides and portents and inundations and volcanoes, the length of the year would change a bit, and things would gradually settle down until next time. If it's in a close orbit around a dim star, the approach could happen more often.

[mindstalk.livejournal.com]

Did Doc Smith describe the orbits that produced Ploor?

[neowolf2.livejournal.com]

Placet is a Crazy Place.

Ok, maybe the science is wonky. :)

[mrteufel.livejournal.com]

Loving this thread!

[neowolf2.livejournal.com]

How about a system that causes the obliquity of the planet to vary wildly, or even flip over?

Also: a planet experiencing http://en.wikipedia.org/wiki/Kozai_mechanism would be fun.

[tceisele.livejournal.com]

Actually, I think there is a lot of potential from a planet that sounds at first like it would be dead boring (and is therefore neglected in fiction): perfectly circular orbit, orbiting a calm and unexciting sun, with zero axial tilt, maybe even a short day (on the order of 10 hours or so), and with enough insolation that the third of the planet nearest the equator is above the melting point of water while the rest is frozen. While this would result in very little climate variation at any given spot, the *individual spots* would vary from each other a *lot*. And yet, unlike the ever-popular tidally-locked worlds, every spot on it would receive enough sunlight that there would be an energy source for living organisms.

What I think we could get from this, is wildly varying biochemistries based on the different temperature bands. Currently, we don't have, say, plants that are adapted to growing on ice at sub-freezing temperatures, because by adapting to the cold they lose their ability to handle the heat in the summer. But with a planet like this, seasons are eliminated and so organisms can become highly adapted to absurdly specific conditions. Around the equator we would have water-based organisms more or less like what we have on Earth. But at the north pole, we could have a niche for plants that are based on ammonia-water mixtures, letting them keep growing down to some really ridiculously low temperature (but completely unable to survive at what we regard as room temperature). Meanwhile, the south pole is completely isolated from the north pole cold-climate ecosystem, so it could independently develop salt-brine-based plants. Voila! A world with three completely independent and mutually incompatible ecosystems! Try *that* on one of those planets with exciting orbital mechanics!

[peter-erwin.livejournal.com]

You're assuming there's no atmosphere (or hydrosphere) to redistribute the heat, I assume?

(Otherwise you're talking about something like Earth, minus the seasonal variations.)

(Except for the slow rotation period, Venus comes pretty close to meeting your specifications: nearly circular orbit, obliquity less than 3 degrees.)

[tceisele.livejournal.com]

Well, a thinnish atmosphere, anyway. Not a greenhouse nightmare like what Venus has, at any rate. I think even an earth-like atmosphere would allow permanently-frozen poles in a situation like that.

[peter-erwin.livejournal.com]

Currently, we don't have, say, plants that are adapted to growing on ice at sub-freezing temperatures, because by adapting to the cold they lose their ability to handle the heat in the summer.

Biological antifreeze compounds (http://en.wikipedia.org/wiki/Antifreeze_protein) have been found in a number of Earth organisms, including plants. (Also: I'm not sure there are a whole lot of nutrients in ice.)


I think even an earth-like atmosphere would allow permanently-frozen poles in a situation like that.

Well, given that the Earth has (at the moment) permanently frozen poles, that's correct.

(I think you're overestimating the effects of seasons.)

[geekosaur]

I was recently reading about bacteria found living at the bottom of glaciers. Not a lot of nutrients, but enough, apparently. Also, I seem to recall mention of bacteria living by munching on trapped grains of iron ores.

[resonant.livejournal.com]

In Robert L. Forward`s `Rocheworld`, two planets orbited each other so closely that they shared a common atmosphere, and tidal waves could bloop over from one planet to the other.

[le-trombone.livejournal.com]

I wonder if anyone has done an atmospheric check on Mesklin. I believe someone must have re-done the math on the surface gravity for Clement, since it's rotation changed slightly from Mission of Gravity to "Lecture Demonstration", but now that we have even faster computers now, I can't imagine a better use than to calculate weather patterns on a planet with an eighteen-minute day.

[(Anonymous)]

Sounds fun. Who do we apply to for the grant?

William Hyde

[dbdatvic.livejournal.com]

We could ask Merlin Corwinsson what factors he used to come up with Ghostwheel's home plane...

--Dave, but that cosmology isn't so much about the planetary systems