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Friday, December 30, 2011

Of Eclectia's Oceanic Motion

Thinking over the planetary wobble of Eclectia, I thought about the effect it would have on ocean currents.

I first thought the planet tipping its pole sunward, that is, "summer," would cause the oceans on the surface of to surge toward that same pole.  "Winter," when the pole tips away, would cause the oceans to head toward the equator.  It would be rather like high tide and low tide.

Modeling this in my mind a bit more, I realized that only the night side of the planet would have a surge in the summer toward the pole.  The day side of the planet in Eclectia-summer would head away from the pole.  When the pole shifts back 2 and a quarter days later, it's again the night side shifting toward the poles and the day side sifting toward the equator.

This, along with the planet's rotation and uneven heating, should set up some gigantic ocean currents that would tend to hug continental shelves, and would perhaps make separate circuits in the northern and southern hemispheres.  If Eclectia rotates the same direction as planet Earth, I think there would be a tendency for currents to run clockwise in the northern hemisphere and counter-clockwise in the southern, just like on Earth.

But these currents would be probably be much larger and stronger than any oceanic current on Earth, due to the strong tipping motion of the Eclectia in a relatively short period.  Also due to the strong tipping motion, even though the currents would in general rotate one direction, periodically they'd be strongly pulled back the other way.  This would also produce tides of a sort.  You would expect then a "low tide" when the ocean current reverses itself and a "high tide" when the ocean comes surging back to its natural direction.

It makes my head hurt to try to figure out exactly when high tides and low tides would come, but it should be in a regular pattern roughly following the fiveday.  So the ocean would be at a regular level most of the time, but for a number of hours twice a fiveday (I don't know how many hours, but probably less than 12), it would surge low, and then immediately afterward it would surge high, followed by a slow ebbing down through normal all the way to low tide.

To make all of this more complex, an individual port city's relationship to the Eclectia "tide" would depend on the orientation of the harbor in relation to the prevailing local oceanic current.  So if Adagio is in the northern hemisphere on the western shores of its continent and its port faces south, the nearby oceanic current going from north to south, the difference between high tide and low tide will not be nearly as great as if the port opened to the north.  A north-facing port would get sucked dry in low tide and flooded over in the high tide under the circumstances I just described.

By the way, all this speculation is designed to add depth and dimension to the story world--not take away anyone's writing freedom or to confuse people or make life harder.  Thanks for listening!

For what it's worth, I think I'll write a story that reveals Adagio is in the location I just made--on the west coast of a northern continent, but with it's harbor facing south...

7 comments:

  1. Cool! Don't forget that only 40% of the planet is covered by oceans, one at each pole and separated by the swathe of land. This is still a lot of ocean since the planet is bigger than Earth - I think x1.75 if I remember right. So this means if Adagio's port faces south, it must be behind a peninsula or hook of the land since there isn't any north-south ocean as such, nor any significant ocean south of a northern coast. Perhaps there's a Gulf of Adagio or something. Might be useful for your story :)

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  2. Good points on the currents. Something that needs to be added in would be the tidal effects of Sheba and Quatermain. Between the perpendicularity of their orbits to the plane of Eclectia's equator, the fact that they are located 23 degrees from each other in their orbits, and the eccentricity of Eclectia's own orbit around 94 Ceti A (I'm thinking 94 Ceti B's effect would be negligible amidst all the other gravitational craziness going on), there's probably going to be some chaotic circulation compared to Earth's simple system.

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  3. Hmmm. I don't remember hearing before now that the polar oceans are totally separated from each other. I wonder how I missed that.

    Oh well, that fact wouldn't effect my speculations much, I don't think. The northern ocean should have a clockwise current and the southern ocean a counter-clockwise current. You would still have tides of the sort I mentioned.

    As for Quartermain and Sheba, I have always thought of them as being pretty small even when combined, significantly smaller than Earth's moon, which is why I considered their effects on Eclectia's oceans to be a lot less significant than its own motion.

    But I realize that I don't recall seeing anything that gives their sizes. I've been thinking something between Phobos and Deimos up to at most, when combined, the size of Ceres. Ceres is listed by Wikipedia as 0.0128 the mass of the moon--not even 2%, even though it has a diameter of around 950 kilometers. Ceres would have pretty weak tidal effect on Earth and less on Eclectia...assuming its orbit would be as far away as the moon's is.

    Have I been off in my assumptions above? Has anybody defined the size of Sheba and Quartermain and how high above Eclectia they orbit? I'd be really interested to know. It could change tides quite a lot.

    As for Adagio, well even as I imagined it, along the west coast of an oceanic branch running north south, a port would naturally face west. But if it were around a hook of land or peninsula, then it could face south. With Adagio being in the northern ocean, though, its port would naturally face north...so the hook of land needs to be significantly more of a hook for Adagio to be a south-facing port.

    So yeah, a "Gulf of Adagio" would totally make sense. Though it could be the "Bay of Adagio" or something...

    Thanks for the thoughtful replies, Grace and Walt.

    So would that mean north ocean angels are cut off from south ocean angels? I wonder which ocean (if not both) the demons would come from?

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  4. The coastlines are likely to be zigzaggy, and there could be a place where the oceans come closer to meeting, even sparking legends that there might be an undersea tunnel or something... hmm, interesting story?

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  5. To get Grace's hyper-fast precession, the two satellites would have to be fairly large to produce that much wobble in Eclectia's axis. Secondly, a major feature of both Sheba and Quatermain is their still hot core sections. To get a body to fit these requirements I prostulated an original planet approximately the size of Mercury. Any larger, and it would louse-up Eclectia's solar orbit; any smaller, and Eclectia would end up doing a slow dance rather than the boogie woogie to to the music of the spheres. I figured the planet was ripped apart during its capture and that capture would have to be geologically recent for the cores to still be hot. The prime ore bodies the cowboys especially look for are probably solidified core material that came adrift during the breakup.

    Thinking about the coastlines, a Bay of Fundy sort of inlet might be interesting for characters to deal with. The orientation and shape of the bay is what makes the tidal bore so extreme. A second extreme might be something like the port of Inchon during the Korean War. At high tide, the harbor's depth was about what one would expect of a port serving ocean traffic. At low tide, the water completely disappeared leaving ships sitting stranded on their keels for six or more hours, twice a day.

    Here's a link to a write up on the Bay of Fundy: http://en.wikipedia.org/wiki/Bay_of_Fundy

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  6. Er...well, your concept of Sheba and Quartermain is very different from what I had in mind. I was working off the statement introducing the two moons as "small." A Mercury-sized moon would not be small by any definition. Mercury has more mass than any satellite in the Solar System. (Even split in half, each half of Mercury would be bigger than the moon, as Mercury is something like 12 times more massive than our moon.)

    It's true that a large satellite as the origin of Sheba and Quartermain would explain their molten core parts. But a smaller body could also have a molten core if the whole thing were molten by being close to its primary star at some point and later got pushed out and cooled (or maybe by an extraordinarily large amount of radioactive materials it its composition).

    The "large-satellite" view could also explain Eclectia's "wobble," as you mentioned, something I had no explanation for, except maybe a large body had passed Eclectia a relatively short time ago, both rending its one satellite in two and setting Eclectia's precession in a fast spin.

    But a "large-satellite" view creates problems, too. Such as a Mercury-sized object would be extremely difficult to rend in two, especially without requiring such force that would run the risk of turning all of Eclectia into a molten lava sphere. Also, large satellites would have the effect of quickly collapsing in on one another again, forming spheres, perhaps in time as short as twenty years or less. Ceres is at about the limit of the spherical shape, as I understand things. Anything Ceres-size or bigger will collapse into a sphere. Smaller than that and a satellite can maintain a non-spherical shape. Which is why I put Ceres as the upper limit to the combined weight of Sheba and Quartermain together, because I understood them from their artwork to be visibly broken planet fragments.

    The tide stuff is all secondary to this consideration. Are Sheba and Quartermain large or small? If large, I can live with that--but they should not be described as small. And we're stuck trying to explain why they aren't currently spherical and we'll also have to deal with some truly epic tidal forces, alongside other strong forces simply generated by Eclectia's rotation and wobble.

    If small, we leave no in-story explanation for Eclectia's precession and the moons' molten cores, but everything else works.

    I believe this one's for you to decide, Grace. Just how big or small are Sheba and Quartermain? This will wind up mattering in future descriptions of the system...

    Thank you!

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  7. I agree with Travis; this is a question of basic world-building that Grace, as head honcho, has to decide.

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