Life on a Non-Tidally Locked Moon

Question

So I'm thinking about writing a fantasy and I want certain parts to be plausible (though I'm sticking way towards the end of soft sci-fi).

In the world I'm creating there is a cataclysmic tide that overcomes the area every few centuries or so as well as several massive tides that come at a seemingly random basis every few years. My explanation for these phenomena is that their world is an earth-like moon around a major gas giant. Therefore, the massive tide happens because the moon isn't tidally locked, and overtime moves around the whole world. The smaller tides would be caused by other moons approaching this moon's orbit. So my questions are:

• Is that at all plausible or am I wrong about how the tidal system would work (non-astronomy/physics major here). Is there another solution that I'm not thinking of?

• How would day/night work on a moon like this? Could there be seasons?

• Where would the habitable regions of the planet be?

• How would the gas giant's magnetic field effect the planet (for story's sake I'm assuming its magically very powerful)?

• What kind of star would this moon need to support and Earth like planet?

• Is it possible for the Planettide to occur over a section of moon in an abrupt fashion, or would it come creeping in very slowly?

• What other interesting or unusual things would be different about this world than ours because of it being a moon?

Answer 1

I'm assuming you've read the multiple questions related to this one... I'll try to answer those that are not obvious from their answers.

Is that at all plausible or am I wrong about how the tidal system would work (non-astronomy/physics major here). Is there another solution that I'm not thinking of?

Massive tides that come at random every few years, let alone every few centuries, are not feasible. Your moon rotates, and the tidal bulge rotates with it, so tides should come in cycles that last in the order of one day or half a day or a quarter of a day. If the moon's orbit around the gas giant is very excentric, tides will be much stronger near periastron (the moment of closest approach), but still easily noted as periodic events. Moons don't commonly have orbital periods in the order of years. A possible model for you would be Neso, which orbits Neptune every 27 years and has an excentricity of 0.57.

How would day/night work on a moon like this? Could there be seasons?

Yes, of course. Day and night only require that the moon rotates around its axis, and seasons exist because that axis is tilted.

How would the gas giant's magnetic field effect the planet (for story's sake I'm assuming its magically very powerful)?

If magic is involved you are free to decide. The moon's orbit might well lie entirely outside the magnetic field. If not, expect interactions with the magnetic field of the moon. That's as far as I can go, being no expert.

What kind of star would this moon need to support and Earth like planet?

Better think of you'd want to have, and then check if it's possible. A Sun-like star would be the obvious answer but it depends on a lot of other factors.

Is it possible for the Planettide to occur over a section of moon in an abrupt fashion, or would it come creeping in very slowly?

Tides follow the rotation of the affected body. In some places, due to the shape of the coast, the depth of the water and other factors, they can rise very fast, while in others they're barely noticeable. But tides cannot arbitrarily accelerate or slow down. Read up on tides on Earth; they're a very complicated phenomenon and many curious things are possible.

What other interesting or unusual things would be different about this world than ours because of it being a moon?

I'd say more frequent total eclipses. Also the fact that there's a great planet close by and that there are other moons would mean that people would quickly understand their home world is not that special (as we on Earth thought it was).