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4 major moon earth-like planet

Discussion in 'World Building' started by caters, Jan 17, 2017.

  1. caters

    caters Sage

    My Kepler Bb planet is just like what the title says, it has 4 major moons and it is earth-like(similar gravity, similar composition, etc. Just the mass and radius and thus density are different. The reason why I say the density is different?

    Well take a look at Earth vs Saturn. Those are 2 completely different planets. But the gravity is so similar, 1g on earth vs 1.065g on Saturn. That isn't much of a gravity difference and yet Saturn is so much more massive and has a much larger radius. This is due to the density. My Kepler Bb planet has a lower density but it is still rocky and still has an iron core and a magnetosphere. So anyway, this planet has 4 major moons that are all in resonance. If they weren't, the moons would quickly be ejected until there was just 1 or no moons.

    Anyway, I was wondering if having 4 moons vs 1 has any effect on the prevalence and severity of volcanoes and earthquakes. Yes having multiple stars would have a profound effect on tides and thus volcanism. But the stars are so much further away because this planet is in the habitable zone so that cancels out a lot of the tidal force from the stars. But what about the moons?

    Could it be that every time the moons line up, a supervolcano erupts causing a volcanic winter across the entire planet due to the sunlight being almost completely blocked?

    And what would an event like this look like? Would it look like first 1 moon, than the second moon going behind the first causing an eclipse that is kind of like a solar eclipse only less blinding and then the third moon going behind the second causing an eclipse within an eclipse and then last but not least the fourth moon going behind the third moon when all the moons line up causing an eclipse within an eclipse within an eclipse and then a sudden drop in temperature because of all the tephra blocking the sunlight which could then cause there to be winter type conditions for an entire year?

    So basically my eclipse would look similar to this at first:


    But of course it wouldn't be nearly as bright but when I look at a full moon, I can see sort of this layering of colors with my eyes as I go out from the moon:

    Blue right around the moon, kind of like a flame

    White light around that blue ring

    Rainbow around that white light

    Second white band of light

    Moonlight then blends into the night sky except for a few areas(moonbeams I have seen, especially in the summer. So bright I can read well in these moonbeams)

    So I can imagine that a moon eclipsing another moon would look like this light I can see on a full moon but with the only visible moon being the closest moon.

    So it would look like just 1 moon when really it is 4.

    But anyway, could this eclipsing of moons and total moon lineup cause a supervolcano to erupt due to the tidal forces from the moons adding up? Or is that too extreme for multiple moons of an earth-like planet?
  2. Hazardous27

    Hazardous27 New Member

    I'm not an astrophysicist by any means but I think for your volcano question you would benefit from reading up on Io. Its the most geologically active body in our solar system as a result of being the closest of Jupiter's 4 major moons to the planet itself (its constantly being pulled in like a gravitational tug of war between Jupiter and the 3 moons further out from it). Its not quite your situation but it might give you an idea of how drastically tidal forces can effect geological activity.

    As for your supervolcano being caused by a conjunction of all four moons my only thought is would the moons be in place long enough to actually do anything significant? I'd imagine they'd continue on their orbits and be on the other side of the planet again within a few hours.
  3. ThinkerX

    ThinkerX Myth Weaver

    Depends on how large (dense/mass) the moons are, and how close they orbit. That many moons...fair shot at least one is in an unstable orbit. Phobos, one of Mars's moons, will eventually collide with the planet, for example.
  4. buyjupiter

    buyjupiter Maester

    Vulcanism is mainly driven by tectonic plate movement, like on the Pacific Rim [Japan, Alaska, western edge of North + South America, New Zealand and on up through the Pacific Islands til you reach Japan/Russia again].

    If you don't have tectonic plate movement*, you need a MASSIVE object like Jupiter/Saturn exerting gravitational effects on a smaller object.

    So in essence, you'd need moons that were much larger than your planet [and this gets into quibbly territory over what constitutes a "planet" in the first place] to get this effect, no matter how many moons you have. The more moons you have, the less chance you have of four/five objects that massive being in stable-ish orbits.

    Also, worth looking into [I'm less sure of this point, in other words], but interference of gravitational effects might be a thing. In other words object A might block object C's gravitational/tidal effect on the planet, depending on mass and orbits and all kinds of other factors.

    *If you muck about with the density too much, you'll lose tectonic plates. The less iron you have in the core [ie the less dense you make the planet, because it's mostly the iron that gives earth its particular density, iron weighs a ton], the less likely it is to have tectonic plate activity. If you don't have a strong tectonic plate [Mars has ONE plate that shifts over an metal core], you don't get strong earthquakes or volcanoes [Mars only ever had shield volcanoes which are the oozy kind, not the explosive supervolcano kind].

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