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A World with a Planetary Ring

Arthur Lawrence

New Member
So, I'm writing a story about a world that once had three moons, but one was destroyed as a result of a battle between an alliance of the realm's races and a dracolich made out of thousands of corpses (makes more sense in context, honestly). I was planning on the event causing a nuclear winter that wipes out most life, requiring my immortal race of faerie folk to step in and re-terraform the world. But now my research is showing that such an event might actually cause an earth-like world to become blisteringly hot, to the point of evaporating oceans. What I want to know is, despite this being a magic world, is it more realistic for the planet to freeze, or burn? If it changes the answer, my planet is slightly bigger than Earth, exerting maybe 14% more gravity (or whatever would still allow for Earth-like life to survive), has two surviving moons that have a gravitational pull proportionate to what the moon has to Earth, and has an average temperature of about 69 degrees Fahrenheit. The Moon was crushed via telekinesis on the dragon's part, then allowed to drift within the Roshe Limit so it could create a planetary ring.
 

Chasejxyz

Inkling
I mean you already have a dragon using magic to crush an entire moon so.....your magic can make it do whatever it needs to.

If a bunch of debris fell to the surface, then things would be pretty scorched, but that wouldn't be for forever. The aerosolized debris would then create a "nuclear"/volcanic winter that would make everything super cold. Either way, things would be very different from before the event, but probably wouldn't need to start from scratch. The Chicxulub crater caused a mass extinction and killed a bunch of stuff...but we still have sharks, coelocanths, ferns. Horseshoe crabs. Lots of species came out of it relatively unscathed and pretty much the same as before.

How far in the past is this? If you're writing about a world where this DID happen and it's been several thousand years since then, things should be pretty normal...or what normal would have been during an ice age, which we do know a lot about since it wasn't that long ago. There would probably be some archaeological sites like Pompeii that were "frozen in time" because of the sudden heat/gases running through (if there was an impact of a larger bit of stuff nearby) which could be some really cool settings for adventures.

The Earth got (was?) the point of boiling off oceans when the [whatever] planet struck us and ultimately created the moon. But you're not having a whole moon crashing into your planet, but smaller hunks of debries. Lots of stuff falls to Earth every day but most of it burns up in the atmosphere. Most of the pieces from your moon seem to be in the zone to make a ring, so you probably won't have a huge mass-extinction on your hands....but also this is very much fantasy. I highly doubt there's going to be a reader who's a planetary ecologist and they're going to do the math to prove you wrong. It just needs to sound plausible enough.

Also if this was in the past (and not something we see "live" on the page), there's going to be myths/legends/religious stories about what happened, and those very easily can obfuscate the truth. A severe flood could be interpreted as a global flood like Noah's, for example. In a world without fast/instantaneous communication, it's hard to know what other parts of the world went through or how wide-spread a disaster might be. So you can make things sound worse than they actually were or be not 100% accurate because that's what the peoples of your world honestly believe since they wouldn't have the tech/tools/knowledge to have an objective understanding of it. Think of Thread from Pern, for the longest time the people of that world could piece together that it came when a "red star" approached their planet, but not more than that. They couldn't know about the oort cloud or that the periods that "skipped" threadfalls were because the planet was knocked out of orbit a little because they didn't have that level of astrological knowledge. So unless you plan on pulling a Pern and actually telling us the hard science behind it....don't worry about it that much. Let the mythologies of your world build up a layer of plausible deniability for the things you can't totally figure out.
 

Arthur Lawrence

New Member
That makes sense, Chasejxyz. This is an event that happened WAY WAAAY in the past of the world, but many of the races live well past a century, so it feels a little less long ago to many of the surviving civilizations. Well, except for humans. And, yes, I suppose magic is a powerful force in this world, but I'm making a point of not letting it be a catch - all thing. Beings like that dragon are rare, at least in the history of mortalkind. For the most part, science is still science, to make the fantastical parts feel more impactful. The scorching part still puts a monkey wrench in my lore, but... it's a good monkey wrench, I'd say. Makes things interesting. Just means I have to adjust a few things to make sure everything feels reasonable. Thanks!
 
I'm not sure the destruction of a moon would cause either of those events to happen. It would throw the climate out of whack, since it will affect ocean currents and stuff. Which sucks if you live on the planet at that time (the gulf-stream reversing would give some interesting climate changes in both europe and north america after all). But its nothing that a bit of migration and a few hundred years to adapt wouldn't fix. The whole place would still be liveable, just in different places.

After all, the whole point of forming a ring would be that not all stuff plummets to the planet in one go. It stays up there as a ring after all. You would get some debris falling to the planet. But you would just see them as shooting stars and have the occasional explosion which flattens a forest when the piece is bigger. You need fairly large pieces to get mass extinction scenarios like the dinosaur one (which was 10+km in diameter).

All this to say that you can probably do whatever you want. A magical war where a whole moon gets destroyed means the magic at play will be big. Who knows what the fallout of that would be. And, as Chasejxyz points out, if it's long enough ago then it will be the stuff of myth and legend anyway. And those stories might not even be believed by everyone.

Side note, if it's long enough ago, the rings would disappear. Predictions for Saturn's rings are that they will last for "only" another 100 million years or so. Which is a blip on the galactic time-scale.
 

jacksimmons

Scribe
To answer your question: I am of the understanding that the moon affects tides and seasons and the length of the day, among other things. A disappeared moon could have an large impact on these things after a few million years. But I don't believe the difference would be particularly noticeable immediately. Fallout from a destroyed moon however could cause extinction level events, where impacts create volcanic reactions that block the sky and disrupt the ecosystem.

One of the prevailing theories of planetary ring formation is that they are made of shattered moons. So no qualms there as far as I can see.

Is it possible you're thinking a little too much about the hard science? There's nothing wrong with delving deep and getting super realistic if that's what you want to do, but in a fantasy setting where there are dragons using telekinesis to destroy moons, it might not matter so much. The people who are interested in the hard science are not likely to follow your undead dragons, and the people who love the fantasy elements are likely to suspend disbelief long enough to not particularly worry about the exact physical consequences of the breakup of a moon on a planetary body. If you know what I mean.

If it's useful and fun for you to think about then that's cool. But is the exact physics going to have a huge impact on the story? It seems like a lot of information to convey for very little return to the reader.

I would imagine that in the context of the story you nor the reader will need to worry about Roche Limits and tidal forces.
 
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