Im working on a story about a new exoplanet discovery and its subsequent "Near Future" colonization.

The planet is close to its parent star. As such, I have decided to give it a sizeable molten iron Core and a super earth radius (for increased Magnetic field production reasons).

But I have also decided to give it a composition mostly comprised of Rocky mantle rich in Iron deposits. As well as a variety of other metallic properties. What effects, if any, would a planet with such a composition have on technology?

Magnetic interference? Communication issues?

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    $\begingroup$ Well, it depends on how hard the aforementioned technology hit the planet, I guess... $\endgroup$ Sep 16, 2019 at 14:25
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    $\begingroup$ Earth is a planet rich in iron ore deposits. Best iron ore (62% iron) costs less than 100 US dollars per metric ton (that's 10 US cents per kilogram, or 5 US cents per pound.) $\endgroup$
    – AlexP
    Sep 16, 2019 at 15:01
  • $\begingroup$ Are you asking about the way technology would develop on the planet or how this would impact some visitors to the planet ? $\endgroup$ Sep 16, 2019 at 15:15
  • $\begingroup$ How it would impact the technology of visitors to the planet e.g colonization $\endgroup$ Sep 16, 2019 at 15:46
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    $\begingroup$ The Earth can already be considered rich in iron (as @AlexP already mentioned). I guess the answer should actually look into the question "What if an exoplanet is poor in non-siderophile elements?" $\endgroup$
    – Alexander
    Sep 16, 2019 at 19:52

3 Answers 3


The earth changes its magentic polarity every few thousand years or so.

The hypothesized reason is due to internal convection changing the dynamo. Note that earth's core is largely iron and nickel.

Since your planet has a much larger proportion of iron in the core and a much larrger radius, it can be assumed to fluctuate its magnetic polarity much sooner as the opportunity for convection currents will be more, and as iron is more magnetic than nickel (.https://physics.stackexchange.com/questions/318215/nickel-iron-and-cobalt-attraction-strength-to-a-magnet).

How soon will depend on the exact composition, so you can set this as per your convenience. But since this is still a geological phenomenon, and magma has a very high density, so the change in magnetic polarity should not be very frequent. I would suggest to pick a value in the range of 100-200 years.

It also suffices to say that due to large presence of iron, many a surface rock will turn out to be magnetic, with varying strength at different areas.

Given this increased magentism, any solar flare is bound to produce much stronger reaction, which will also be amplified by the short distance between the planet and sun.

So, you can expect

  1. Technology for infrastructure etc to be complicated. For example, simple digging etc will take more time as the tools will keep getting magentised more frequently

  2. Magentic interference to vary and make electric transmission difficult/ unreliable at times.

  3. Much more outages of electricity grid due to solar flares

  4. Which will lead to less reliance on technology that we see today due to frequent blackouts

That said, technology is not just for electronic products, but also for biotech, energy, space, nanotech etc, which should not have that profound an impact due to increased iron.

  • $\begingroup$ "Since your planet has a much larger proportion of iron in the core, its bound to fluctuate its magnetic polarity much sooner" really? do you have a reference for that? $\endgroup$ Sep 16, 2019 at 19:39
  • $\begingroup$ This answer is wrong. There is no way to predict the frequency of magnetic reversals based on the size or composition of the core. $\endgroup$
    – Gimelist
    Sep 16, 2019 at 22:33
  • $\begingroup$ @StarfishPrime I don't have a source for it, from my readings, the whole concept of changing polarity is a rare phenomenon which hasn't been studied much, and only has hypothetical theories as reasons. $\endgroup$ Sep 17, 2019 at 0:21
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    $\begingroup$ @Gimelist: I realize now on reading the answer that it was coming across as science based than science fiction, so have corrected the language. You are right that there is no way to predict it, and I didn't mean to predict in the first place. I'm still new to this site, let me know what is a better way to write such answer :) $\endgroup$ Sep 17, 2019 at 0:24

What effects, if any, would a planet with such a composition have on technology?

Not much. The strength of Earth's magnetic field is measures in tens of microtesla. Even if you double that, you will have around tens of microteslas. For comparison, a fridge magnet has the strength of around 10 millitesla. This is 1000 times stronger!

The fact that it is much closer to the star could be a problem, but you are not asking about that.

Iron deposits

No problem there. Are you are probably aware, iron deposits also exist on Earth. There are mining operations to extract the ore:

enter image description here

Ore extraction equipment is sophisticated with lots of electronics and wireless communication. It works just fine without any protection from the magnetic field in the ore. Furthermore, as you can see the ore is red. This is because it is composed of hematite: iron oxide, which is not particularly magnetic.

That said, there is a naturally occurring mineral called magnetite, which is a different type of iron oxide. When walking over rocks with magnetite, the worst that can happen is that your compass needle is deflected and does not point to the magnetic north any more.


EDIT1: This answer was given very early and the question was worded in a manner suggesting that OP is interested in how a local civilisations technology might developed.

I would need to know more about the planet to give a comprehensive answer.

However some things can be predicted. I'll assume that the planet is in general richer in metals and not only richer in iron.

I could see metalworking starting earlier, as finding useful quantities of pure metals in nature, think gold and other metals found as nuggets, will make it easier. The fact that ore will be more common will make a start of the bronze age easier. The mediterranean cultures had to get the tin they needed from England or Afghanistan.

Later in history the grater reserves of rare earth metals will make high tech devices easier to produce.

Overall such a planet would probably develop technology faster, because there are more easily available resources and it will be easier to develop a periodic table with more known pieces of the puzzle.

  • $\begingroup$ Apologies for the lack of specificity. Yes i would also assume the planet was rich in many other metallic properties. but my question (poorly asked) was more geared towards futuristic colonization. And the geological effects such a planet may have on technological devices and the like. $\endgroup$ Sep 16, 2019 at 14:52
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    $\begingroup$ @ZachJohnBruce Yes, I can see that know. However the question was worded differently when I wrote the answer if I remember correctly. Well, that happens. I see you accepted mu's answer. Usually you should wait at least 48 hours before accepting an answer so that people from all over the world can take a look at the question. $\endgroup$ Sep 16, 2019 at 16:39
  • $\begingroup$ Apologies, as i am new to this. Accepting an answer prohibits others from being able to respond? I'm still learning proper etiquette. $\endgroup$ Sep 16, 2019 at 16:57
  • $\begingroup$ No, others can still answer but accepting an answer says that this this exactly what you wanted and is meant as a reward. What do you do if someone puts up a better answer? $\endgroup$ Sep 16, 2019 at 19:21

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