The hypothetical world is for all intents and purposes earth or very close to it. So what would the effects be if the magnetic field were either stronger from the start of the planet, or if the magnetic field suddenly became much stronger on a existing planet.

I already know that the planet would receive less solar radiation (possibly eliminating auroras), but other than that I don't know what else it would do, except maybe confuse animals sensitive to the earths magnetic field.

I'm looking for answers on how this might affect the evolution of life and technology, as well as the affects on both of those if the earth's magnetic field rapidly gained power.

I would like to know the affects of that a change would have from a minor one, up to a change sufficient to wipe out humanity. I'm not sure what substantial effects a powerful magnetic field could have but it seems to me that any force in a large enough amount would be able to have catastrophic effects.

  • $\begingroup$ based on my opinion it will be better for you to have an equal chance of best answers for each condition (both initially stronger and suddenly stronger) if you split it on different questions. In my own opinion, if you bundle them as one question, each answers answering both condition on the question, will have a chance that half of them might not be suitable for you. I mean, how if the best answer on your opinion spreads on two answers? (like the best solution for initially stronger condition on A's answer, and the best solution for suddenly stronger condition on B's which will be your pick?) $\endgroup$ Commented Jun 5, 2015 at 8:00
  • $\begingroup$ Why would strong magnetic field kills anything except credit cards, I don't think it is fatal since MRI scan is hell lot mightier and cooler (pun intended) second probably to a magnetar then those confused flocks will attempts bird pyramid lol. $\endgroup$
    – user6760
    Commented Jun 5, 2015 at 12:34
  • $\begingroup$ As a physical force a strong magnetic field would have potentially catastrophic effects if strong enough, water is dia-magnetic and can be levitated in the air by a incredibly powerful magnetic field. I don't know exactly what might happen if the field was strong enough but a strong enough electromagnetic field can display strong physical effects so that's proof it would certainly do something. $\endgroup$ Commented Jun 8, 2015 at 1:44
  • $\begingroup$ If strong enough, the life as we know it would probably not exist. For one, our nerves use electric signals, and charged particles/ions/etc. in a strong magnetic field are deflected, depending on the orientation. So I am not sure "Nature" is clever enough to make work. $\endgroup$ Commented Jun 10, 2015 at 15:32
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    $\begingroup$ Since MRT isn't too harmful and has very strong magnetic fields, the effects on animals/humans shouldn't be too severe. $\endgroup$ Commented Jan 17, 2016 at 22:06

3 Answers 3


Just some ideas off the top of may head:

I don't think a planet with a magnetic field strong enough to kill would be plausible naturally. Your talking about a huge amount of energy to generate such a field, likely the crust would be molten if that much energy was inside the planet.

The earth's magnetic field strength is about 0.5 Gauss and that of an MRI upwards to 30,000. Strong enough to yank a thousand pounds sideways at about 25ft or more.

Based on the fact that you stick humans in a 30,000 Gauss field with no will effects, most biological effects directly on life forms can be discounted.

The major effects would be very large and dense radiation belts that would trap ionic particles. These might be visible in they grew dense enough and might reduce insolation. At the poles, they could funnel dangerous amounts of radiation to the ground.

The in-fall would produce a lot of radio noise, possible jamming virtually all frequencies all the time. Aurora would be huge and constant, possibly blotting out the stars entirely.

But a lot of cosmic radiation would be blocked which is one of the primary producers of DNA mutation so variation would decrease and evolution would slow.

Cosmic rays also play a key part in the formation of ice crystals at high altitudes, so weather and climate would be affected but how I don't know.

Such a field might attract ferric meteorites towards the poles until they heat atmosphere and but heat of reentry sending them past their Currie point and shutting of the meteorite attraction to magnetic fields. When they hit and cooled however, a 30,000 Gauss field might be enough to make the tumble along like tumble weeds.

In geology, magnetic materials are rare in nature. To be magnetic, a material must be in some from of crystal matrix because the field develops between the paired electrons of atoms, not with them. The covalently bonded single atom of iron in hemoglobin, for example, is not magnetic. If it were, an MRI would be a very unpleasant experience. Only meteoric iron and lodestones are the only naturally occurring magnetic ores of iron.

The plasma channels of lighting would likely be constantly deflected sideways. This might lead to greater charge differentials developing between the clouds and the ground if the lighting can't jump the gap until it grows monstrously strong. In any case, lighting will strike far off to the side of the storm. Lighting might equalize charges within the clouds and ground for a long tie until a megaton lighting bolt finally jumps between. Ground lighting might shoot along the ground from hill top to hilltop.

Animal life would likely widely employ magnetic navigation using lode stones in specialized neurons like migratory birds do. On earth, the lodestones only provide a bearing if you travel a few hundred miles. On the super-field planet it would provide information constantly. In addition such a field could provide not only direction north south but also latitude by measuring the up-down deflection as the field curved. In principle, it could be used to measure altitude as well as bearing.

Animals might be far more wide ranging as a matter of course being much better able to navigate back home. Scent might play less of role in laying markers for navigation.

I think, but will have to check that electrical sensing, like that used by sharks, would be more powerful and longer range. Animals that generated strong electrical currents, such as electric eels might find themselves yanked around when they tried to deploy the current. On the other hand, they might use it as a means of sudden propulsion instead.

Spontaneous electrical currents in seawater or wet earth would be much stronger. These current arise when ionic charges such a Na+ move in the water across the fields. Trivial on earth but at 30,000 guass much less so. Plants might tap these currents for energy

In terms of technology, iron tools would be hard to use as they would pull constantly towards the poles. Copper, brass and bronze would be the primary metals. If you shot an iron or steel arrow, it take off towards the nearest pole very quickly.

On such a planet, iron projectiles might be super weapon as long as you could move the things (keeping hot past their currie point would work) then place them side of the target opposite the pole, then let it cool let go.

However, it would be easy to make a generator. Just a hoop of wire stuck up perpendicular to the field and spun by a water wheel would generate a significant current. Conversely, ambient impedance (electromagnetic friction) would be enormous, draining power from any long wires used to transmit power.

For a motor, like a generator, you'd just need the rotor and could use the ambient field as the magnets. The motors would have to aligned with the field at all times and you'd have to put them in a gimbal to use them in a vehicle.

With a 30,000 gauss field you could probably "sail" by using electromagnets to pull or push from the poles. By adjusting the relative strengths of the magnets north/south and the force vectors they exert on the vehicle, I'm pretty sure you could get any vector you wished in a 360 degree arc except maybe perfectly perpendicular to the field lines.

Such a craft might have a vertical windmill with generator rotors inside generating current to an electromagnet. Or not, as the generator would cause a lot of friction against the field, possibly more than the electromagnets could overcome (no-free-lucnh.) Such a magnet would need a ferrous core so they would probably have to use heat to turn it off completely.

Such a craft might make use of aluminum and other diamagnetic materials that are repelled by magnetic fields (that's how the aluminum separator in a recycling plant works, ferric metals go one way diamagnetic go the other.

There is a powerful ground wave in the earth that is used for some radio frequencies and it strongly affected by solar storms and thus the magnetic field. I do not know the details but it might be possible to harvest the ground wave for power just by sticking conductors in the earth. I think Tesla worked on that but abandoned it because the field strength was to low (but again, don't remember the details.)

If you do want to look build a world with a wildly powerful magnetic field, I'd suggest investigating magnetar. These are neutron stars that spin so fast their magnetic fields are extremely powerful, enough to stretch atoms out into thin lines.

With stellar systems looking fairly unstable these days, you could postulate a system that forms from two other systems, one with a magnetarand one with a terrestrial world, the systems collide capturing a magnetar in a planetary orbit. Then a terrestrial world could get swept up as moon of the magnetar. Even at great distances, the magnetar's field would affect the planet. If the planets pole of rotation was largely perpendicular to the magnetar's field at the planets orbit, the fields would merge making the planet appear to have a super powerful magnetic field.

Such a field would impart a lot of energy to the planet's core leading to more vulcanism. The planet would be nearly completely immune from stellar storms and cosmic rays because the magstar would trap them all. The planet would have to be orbit above or between the magstars radiation belts.

In that case, you might have a field strong enough to fly in. Certainly, in space it would make magnetic sails a serious form of propulsion. If nothing else, you could launch radiation shielded spacecraft from directly over one of the magnetic poles.

A sudden increase of the earth's magnetic field to 30,000 gauss would have civilization wreaking effects. First, all long distance power lines would fail, likely most generators and electrical motors because the earth's field would swamp the fields of the magnets in both. Radio noise would jam most frequencies. Most electronics would fail due to increased impedance.

Great herds of junk cars would roll off towards the nearest pole. Skyscrapers would face lateral forces they were not designed for. Knives would fly through the air and guns would, for the first time in history, kill without human agency as they shot out of cabinets and bludgeon people to death.

If it happened quickly, it would be an cataclysm. If it built slowly, people could adapt in interesting ways.

  • $\begingroup$ The magnetic field on the surface on average is more like 0.3 Gauss, maybe 0.31 Gauss (31,000 nT) instead of 0.5 G. Second, the magnitude of the field at the surface is not as important as the magnetic moment. The magnetic moment is what we should be looking at. We are constantly living in a 0.3 Gauss field but the magnet is 12,600 km long (pole to pole). The magnetic moment determines the force the magnet exerts. $\endgroup$ Commented May 25, 2016 at 21:54

Well, there are effects that we can predict easily:

  • Putting stuff orbiting around the Earth would be harder (parasite Eddy current would have much stronger effect)
  • At same time astronauts around Earth would receive much less radiations from space
  • Certain metals would be heavier due to attraction caused by magnetism.

The third point already make problematic our technological evolution because carrying heavy stuff requires more effort and also it is harder to came to the conclusion that "mass" and "weight" are different things (wich is the base for all modern physics, constructions and machines building).

I would argue such a world would make easy the born of small cities with self sustained elettric reactors (cannot make long electric lines). Telecomunication becomes harder.

What about life evolution? A magnetic mantle would possibly attract certain metals, so due to different weights it is possible that concentration of certain elements at ground level is different forcing a total different life (In example, no Iron for Blood).

That is already not keeping into account the fact that to be so much magnetic the Earth core should be different in composition than it is actually.

There are also effects that we can't predict easily (for example phenomena wich we still don't know how exactly works):

  • Does storms will be the same?
  • Does Eddy currents would cause superficial melting of certain areas?
  • Does magnetic Earth would cause different kind of storms?

Also, since things have different weights it is very possible that Earth density change possibly resulting in a slightly shorter radius and hence a slightly greater gravity wich would make a bit harder reaching the space.

That kind of Earth would certainly allows different kind of minerals to grow, so we could have more type of minerals and gems to actually inspire any sentient being.

Since current magnetic field is (believed to be) generated by movement of molten metal underground, it is possible that something able to generate a stronger magnetic field implies a faster metal current wich would also cause stronger and continuos Eearthquakes (and that would also dissipates that energy quickly so that makes me supposing that a strong magnetic field would just be temporary making a lot of catastrophic movies far from plausible)


It would probably disable electric devices at high enough speeds in the sudden case. For the initially stronger case the first electric devices would probably confuse a lot of scientists, since the same device doesn't work properly at other positions; this would slow down the development of mobile technologies, since they move a lot, & a strong magnetic field means a stronger electric field from movement relative to the former field, disrupting these technologies.


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