Effects of high magnetism?
I have a head-world idea where one of the planets in it has four magnetic poles. It is a desert rocky planet with carbon based lifeforms on it (mostly underground or in bio-domes). What would the effect of such high magnetism be?
The deserts are made out of both magnetically charged and non-charged rocks and minerals, like purple garnets, bituminous sands (oil/tar/petroleum/asphalt), clay, magnetite, iron-nickel, ferberite,and pyrrhotite.
Other information: The water on the planet is underground. Each pole has a passage to the layer of the planet with the ocean. This is because the temperature fluctuates from 120C° to -90C°. This planet has two moons, the smaller moon orbits the larger moon, which orbits the planet. The planet's radius is 3058 km. It orbits a class A white supergiant.
How much magnetic force would be needed to make noticeable strange effects? What would the effects be?
Also please let me know if things aren't possible. I'm mostly running with ideas right now and nothing is set in stone.
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1 answer
Actually, the strength of the field would change at the planet's surface. If we model the field as a dipole, it is described by the equations $$B_r = -B_0 \left(\frac{R_E}{r} \right)^3 \cos \theta$$ $$B_{\theta} = -B_0 \left(\frac{R_E}{r} \right)^3 \sin \theta$$ $$|B| = B_0 \left(\frac{R_E}{r} \right)^3 \sqrt{1+ \cos^2 \theta}$$ where $R_E$ is the radius of the Earth and $r$ is the distance from the Earth's center. So the field's strength on the surface would be greater than that of the same field on earth's surface. Admittedly, this field is a quadrupole field (see below), but the same principles should apply.
Anyway, I talked about this type of magnetic field in my answer here, stating that a planet with two cores might very well have four magnetic poles. If the Earth had two cores, then the currents should create a quadrupole field, with poles at the Equator and the North and South Poles. I'm not going to copy-and-paste from that answer, but I'll list some of the effects:
- A magnetosphere with a different shape, which could either help or hurt the ability of the magnetosphere to better protect the Earth from charged particles from the Sun.
- Auroras near the equator
It's hard to tell exactly whether these would be good or bad for life on the planet. Chances are, though, you wouldn't see any drastic effects. Although the magnetic field on the surface would be stronger, because the radius is smaller - not because there are four poles.
Do you mind if I comment a little on the rest of the setup? I'll be honest - it's unlikely. It's not likely that a planet would evolve life within the lifespan of a class A supergiant. They live for a short while and then die spectacularly. Is it necessary for the star to be of this kind? I'd suggest something a bit smaller, less massive, and longer-lived.
I'm not sure just how likely the moon-caption scenario is. After all, a small radius means the planet is less massive, and less likely to have moons. To have a moon big enough to have another object orbiting it would require a large primary moon, and so most likely a large planet. Does the size of the planet matter?
Each pole has a passage to the layer of the planet with the ocean. This is because the temperature fluctuates from 120C° to -90C°.
How dos these passages exist? I would think that tectonic effects would have closed them up really quickly. I'm not sure how the temperature plays into it; there shouldn't be much expansion/contraction of the crust because of temperature swings.
I apologize if it seems like I'm being harsh, but there is a reality-check tag here, so I think that handwavium wouldn't be a good option.
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