Calendar Causing Event

[Kaellpae]

We talked about an eruption for the start ofour calendar. What about losing a moon? It would be something everyone saw and I would think that a big change in the heavens like that could be another start to the calendar year? Any other ideas though?

 

[JCFarnham]

Honestly, I think I would be more comfortable with an eruption. Losing a moon is some what more catastrophic that I think would work. With low magical involvement in this setting I'm also not so sure we could get away with it. Sue you could pull the "fantasy card" on it, but that just feels like a cop out, and doesn't really fit with the settings "mood".

You know?

 

[myrddin173]

I agree with JC on this one. The destruction of a moon would cause problems that I don't think the world could recover from. If an asteroid hit it and cause it to break apart the pieces would fall to the planet. An asteroid about 9 miles long impacted the Earth near the Yucatan Peninsula and killed off the dinosaurs. A moon would have many more pieces much larger than 9 miles.

 

[Kaellpae]

What about if the smaller moon just left orbit?
I'm not a big space person, but couldn't the smaller moon be further away and more likely to be thrown out of orbit? And if it were further away it would have less pull on the tides than the closer moon, depending on their sizes I suppose.

 

[Kaellpae]

I don't deny that destroying a moon would be drastic, but if we just lost a second moon due to a further orbit would that be better, or still doubtful to use?

 

[JCFarnham]

If it was far enough away like that then it wouldn't be too much of a dramatic, calender changing fuss in my mind.. I mean if WE lost a hypothetical second moon I'd be more likely to believe it would solidify a calender with a nice, tasty, memorable date. Besides we'd be more interested in the science though maybe not archipelago-ians.

I just think something drastic happening closer to home would make more sense, something that really would force everyone to rethink the way they've been living for X number of centuries. After all changing calender is quite a thing to do, especially if you intend to get every nation you know of to use it as well.

I personally like the volcano idea. If the issue with it was the magnitude of the blast effecting life and stuff if could be toned down... Though I think having a world that's perhaps still reeling from the event would work evn better. It would also be good enough reason to think in terms of "n years since that eruption thing happened".

 

[InsanityStrickenWriter]

I think a volcanoe would be fine. Most civilisations likely wouldn't experience it as a volcanoe, but rather, a tsunami and long winter. The latter could have lasted a decade or so and effected the entire planet. Main thing to figure out is where the volcanoe was, so then we can figure out who was affected in what way.

 

[Kaellpae]

The volcano would be on my island. With a second one forming at current times. Growing as we speak and never knowing when it will go off. Or that was my plan for my recent volcano, have it be young and angry and active instead of blowing up like the calendar making volcano.

I just wanted to be sure that there weren't any other ideas of something that could cause us to make a calendar. We had mentioned a possible second moon before.

 

[Ravana]

The only problem I have with using a volcano to set a zero year is that I'm unaware of any culture that has actually done it… and volcanic eruptions happen all the time. Even eruptions such as that of Thera, which caused or contributed to the destruction of entire civilizations, wasn't used by the surviving ones this way.

(By the way, Kaellpae, if you aren't familiar with Thera (aka Akrotiri, modern Santorini), you should definitely look into it, because it would be great background for what you are doing with your island. Little island about equidistant from Athens, southern Anatolia, and Crete? Wikipedia has a great 3D rendering and satellite photo of what's left of it today, after the third most powerful volcanic eruption in recorded history—perhaps four times as strong as the Krakatoa one—blasted two-thirds of it into the atmosphere and spread it across much of the Eastern Mediterranean some 3600 years ago. It would be good for everybody to look at, in fact, as it is the only one even remotely that strong that took place in Western Civilization since writing was invented: find out what it would have done to your island, however many hundreds of miles away.)

Losing a moon? Actually… that's not too hard to handle: no magic required. And if the previous calendar was based in part or in full on lunar cycles, that would be a great reason to start a new one. Give me a few to check some references and knock it together.…

 

[Kaellpae]

Right off the top of my head I don't know any that use the lunar cycle, but I know if we had a second moon and one night it wasn't there when it was supposed to be I would be freaked. It would definitely seem an act of powerful magic.

 

[Ravana]

[Approximately one "few" later…:]

Okay, I'm sure an astrophysicist could find some problems with the following; maybe a mathematically-adept SciFi reader could, were he inclined to do the math. I can't, by the way, since a precise solution involves differential equations, and no matter how much I may seem to "know" from time to time, I never even came close to calculus, let alone got out on the other side thereof. (In fact, a precise solution isn't possible, from what I understand… not with calculus, not with all the computing power on the planet. So we only have to worry about whether or not someone can approximate better than I can (easy enough)… and cares to bother (unlikely).)

While this can work for any number of moons from one to infinity, anything more than two would be gilding the lily—and if we happen to want more, I know where we can find them anyway. So: our planet starts out with two moons. To keep things simple (!), I'm going to have both of them be just about the same size… which also means they have to share an orbit. As far as I can tell, the best solution for this problem is not to have them on opposite sides of the planet, as might seem intuitive (and would certainly work under some conditions), but to have them separated by 120° (a third of the sky). They start out orbiting the planet in pretty much whatever period we want, since to change the period all we have to do is change mass and distance. The closer they are, the faster they have to be going. Also, the closer they are, the larger they will appear.

"Appear" is a very important word here, since this depends not only on distance, but also on diameter… which depends on mass and density. So we could have moons twice as far away as Luna is from Earth, and as long as they were four times as big around, they'd look exactly the same. Not too likely, since the required density would be too low. On the other hand, there is plenty of range between Luna's density and that of, say, a comet: in fact, it's the second densest moon in the Solar System, about 3.4 times the density of water; only two others have densities more than twice that of water. Upshot: we can have two very conspicuous moons orbiting in pretty much any period we like. Again to make this simple ("You keep using that word. I don't think it means what you think it means")—and to make people less inclined to check the math—let's say they orbit at right around 30 days, give or take a couple, and appear two-thirds the size of Luna.

They can also be pretty much any color we want… though some (white, gray, yellow, orange) are more probable than others (chartreuse, heliotrope, paisley). And can vary in brightness, since that's a function of what they're composed of… along with distance and size. Simple (this one really is) assumption: they're both dingy white.

So we now have our starter moons. Here's where things get fun.

Around about, oh, 311 years ago (I just pulled that number out of the air, of course ), a small, dense body, maybe a tenth as massive as our planet, passed really near to ours. Really near: in astronomical terms, the only meaningful difference between that and a direct hit was it didn't hit. Contrary to accepted wisdom, horseshoes and hand grenades are not the only things in which "close" counts. It also counts in gravitationally attracting bodies.

I imagine most of you can see where this is going.…

While this rogue planetoid was only a tenth as massive as our world, that would still make it three times as massive as the moons I suggested, maybe more; and if it passed even closer to one of those moons than it did to us, particularly if it was the one in the trailing position, and it was going in something resembling the same direction as the orbit does, it would accelerate the moon out of its orbit and off into space. And lest anyone object that astronomical objects don't move fast enough for it to have receded from sight in the intervening time, remember that our planet has gone around its sun 311 times since that day. If all it did was alter the orbit, no, that wouldn't be enough time for the moon to "drift" that far away—but I'm not talking about drifting: I'm talking about a quick boost past escape velocity, and once you've got that, there's no coming back around.

Just to make sure, though: the rogue crossed our orbit at an angle of, oh, say, 30°… so the movement wasn't just "away" from our planet, it was also in a direction our planet wasn't heading. We've also added the pull of the leading moon in the pair—that's why I picked the trailing one to be the victim—and for an added nail in the coffin (as well as a nice added touch to occur in a moment), the moon was at a point in its orbit where it was coming around from the far side or our planet and headed sunward, so we can throw that little extra in as well.

I didn't even have to smear it all over our sky to get rid of it.

I'll do that in part 2.

 

[Ravana]

I hear some of you asking (I hope that's you: I'm hearing something in my head…): "Wouldn't this near-miss cause all sorts of other problems? Like crazy tides, bad weather, plagues of frogs? Not to mention messing up the orbit of the remaining moon?"

Well, of course it would. Okay, maybe not the frogs… but I can probably one-up all the others.

We did want a cataclysm, didn't we?

Assumption: the rogue planet was fairly dark; that, plus the angle of its approach, and possibly its speed, kept it from being noticed until it was close. Maybe a decade or two before nearest approach. Maybe a whole lot less… in fact, if it was moving rapidly (and better for our case if it was), it wouldn't have been spotted at all until the last couple months. Then, lo! in the sky! A new star! One that's getting awfully big… you think people used to panic at comets? Everyone begins expecting the end of the world.

Then: the tides start going crazy. Not just the ones in the seas—continental crusts would be perturbed, too: earthquakes, volcanoes (didn't somebody mention one of those?).… Then the weather, particularly as tides shift and ash gets spat into the air. Maybe the frogs did freak out. What does that leave…? Oh: right.

Now for the really fun part: the moons go out.

Yes, that was plural.

If we have two moons separated by 120°, one or the other of them is always going to be visible at some point during the night; often, both will. This is the other reason why I made it the trailing moon that gets yanked—and why I had it moving sunward when it did. The other moon had just gone new. Just as everybody started to realize that the new "star" wasn't getting bigger any more, maybe even a bit smaller, they also realized that the one moon they should have been able to see wasn't quite where it belonged any more… and then began to notice it seemed to be getting smaller, too. And the other was nowhere in sight—even though that's right where it should have been. Might have even taken longer than it should have to reappear… thanks to the backward tug of the now-receding planetoid.

It comes up again eventually, of course… but now it's in a different orbit. One that probably has yet to stabilize. Looks like it's time to throw out all the old calendars and make some new ones.

Which, of course, was where this all started.

•

Yes, some of that is piling things on—but since I can't do better than an approximation at the math, I figured it was safer that way; besides, the more, the scarier. Or words to that effect. Note that even the foregoing still allows quite a bit of latitude: for instance, the two moons have to be about the same mass, but they don't have to be about the same diameter, color or brightness. Maybe the one we still have was lower density, making it larger, and quite possibly more reflective—it has some surface ices, say; the one we lost was denser, visually smaller, and darker to begin with (red?), so it would seem to "disappear" even faster. Oh: I also mentioned I could still smear the lost moon all over the sky. Maybe not "all" over… but it could partially fragment under the tidal stresses, causing it actually get smaller even while it was receding. Most of the material would continue along the same course, a lot of it (especially the largest chunks) might pull back together, but some bits could have fallen on our heads—possibly are continuing to, as we pass by our last point of union annually. What's the end of the world without a good meteor shower or two, after all?

We get even more wiggle room simply by adjusting the age of our system: the two moons we had didn't need to be in exact orbital equilibrium (and, yes, such things do happen, though in our system it's only with big planets and tiny moons: Jupiter and Saturn both have several such sets). Perhaps they were just nearing it, with one being drawn in from a wider orbit, and the other being pulled outward from a nearer one: the process would have taken tens of millions of years minimum, so no problem for our old calendar-makers there—they never would have noticed the differences. For that matter, they don't have to occupy the same orbit at all (this would certainly be more convincing to those inclined to raise scientific quibbles): it would be easier still to lose a lighter, more distant one, and we could still have all the rest happening. The rogue planetoid might have even done us a favor, yanking away an outer moon that was in a converging orbit with an inner one: that smash-up would definitely have been a "bad thing."

At any rate: yes, we could have lost a moon. Up to the rest of y'all to decide if we want that. My work here is done. [<-- green, cheesy smile]

 

[JCFarnham]

Well that certainly squashes my worries about physics

In fact if you reckon it would mess with tectonics and such then I think we might have our innoculously named "Event". On top of this I'm almost certain a massive dark thing appearing in the sky and stealing the moons, at which point all hell breaks lose [valconoes especially ], would be the stuff that seeds religions. If everyone agrees to this I think I have that pesky religion I've been searching for.

Wicked.

 

[Ravana]

Hee hee. By the way, remembered something last night after I'd gone to bed that I'd meant to mention (again, this is more in the nature of "piling on," just wanted to note the possibility). Another thing that might make it look like "the moon was going out" could be loose particulate matter from the surface of the planetoid—or from vulcanism triggered on the planetoid thanks to our gravity's influence, or even in its atmosphere: nothing says it can't have one—falling on the surface of the victim moon, darkening it and changing its color.

 

[Kaellpae]

I really like the volcano concept, this idea struck me as more of a panic event than an eruption though. What's everyonee else think of Ravana's explanation?
@Ravana: Thanks for taking the time to explain all those details. I have to do all my typing on a phone so it would have taken forever to research and type all that up.

 

[Donny Bruso]

An eruption on your island isn't going to trigger the kind of mass hysteria that myrddin wants to trigger his global calendar rewrite. You might use that as why your people in particular chose to rewrite it if you want, but personally I think that a moon vanishing is a little more impressive to astronomically ignorant people. (I mean that they know nothing of astronomy, not that they are really dumb)

We wouldn't freak out about it because we have the telescopes and space program and overall technology to explain what is going on. No one in any of our countries has that capability. If suddenly the tides are screwed up, there are massive earthquakes and meteor showers, volcanic eruptions for those islands that choose to have them, people are going to assume it's the end of the world. Remember that in earth history religion is a dominant factor in most people's lives; and I think any minister worth his salt in that setting would be preaching that the wrath of god has come, repent or be destroyed.

So then when the world doesn't end, (Kinda like that rapture thing earlier this year) people are all relieved. They have a massive party and get totally annihilated on the local booze (because let's face it, parties are just an excuse to drink). But hey, wait, we only have one moon now, and the one that vanished was what we based out calendar on. (Not my calendar, my hooligans picked the other moon just to be contrary) So now we need a new one. Well, maybe after the hangover clears up...

But you get my point. I'm not saying that a volcanic eruption can't have global effects. It can. I'm saying that as you move outwards from the volcano there is a rapidly falling chance that the impact will be significant enough to cause people to panic and change their calendar, which, all of them being lunar or solar, would actually be unaffected. Losing a moon upon which the calendar is based forces the rewrite that you all want.

 

[Ravana]

Basically my thinking—though even if both moons were involved in the calendar (which in the most "basic" of the above examples they were, since they had the same orbits), having the remaining one assume a new orbit will be enough to mess up most people's calculations. And, yes, it's far more likely to be considered a seminal point in the world's existence, which was my bigger concern, even if the still-unsettled orbit of the remaining moon hasn't yet diverged enough to make more than a minor and easily corrected-for difference.

Besides, we didn't have the lunar calendar evenly dividing the solar one anyway… and the length of the year hasn't changed. So some societies might well go on using their old months—but would still agree that counting years from the date of the cataclysm makes sense. (Note: the year actually would get longer—just in case any science nerd wanted to bring that up: the new, slightly lower mass of our planet/moon system would cause us to spiral outwards a bit—but the change would be so slow and gradual it would take thousands of years, probably millions, for anyone to realize this. In just three centuries, and even allowing for the good sharp tug we got, the amount of difference to date would be minutes per year at most.)

Not that my desert nomads care. They never worried about counting years anyway—they consider it a silly conceit. And the only thing they used the moons for was light during night raids. The only reason they kept track of the solar year at all was so they would know when certain plants they collect would be ready, and when they were all supposed to come together for their annual shindig. So they just shrug and agree with whoever they're talking to when the latter try to tell them it's now year 311, as opposed to whatever other number would have applied under their old systems.

 

[Kaellpae]

Hell, if something similar to what Ravana described happened today there would be riots. Even if alll the scientists said the planetoid wouldn't hit us. Cults starting up, looting, and I'm sure plenty of other armageddon things going on.

 

[desertrunner]

This sounds like just the thing needed to get us going. Lower and screwy tides, volcanoes, and earth quakes would be more than sufficient to bring my island out of the depths and explain why no one has touched it before the guild. Many would probably believe it to be cursed since it sprouted up from the missed apocalypse. Such superstisions would not deter my traders since the only thing they believe in is riches. What do y'all think?

 

[desertrunner]

So what details do we want to agree upon for our moons? I'm anxious to start playing with this new possibility.