In a world I am helping build there is a certain group of people with the ability to produce electricity from their bodies (and control it, I believe), an additional power I gave them was the ability to sense magnetic north. My assumption was basically "if compasses can sense magnetic north, there is probably a way for a creature to do it.). I do not know the nature of magnetic fields, but since I want these people to be seafarers, my desire is to place magnetic north and magnetic south off-kilter like it is on earth. My hope is to make it where, if they can sense the direction of magnetic north and magnetic south, and their relative distance to both, they could know exactly where they are on the planet (in terms of coordinates. However, I don't know if it is feasible for them to be able to sense magnetic south in the way they sense magnetic north (note, I want to know if they can sense the direction of the two points, and their distance to the points.) if they can, would this aid their ability to navigate like I think it will?

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    $\begingroup$ I think my new compass is unique it ONLY points north... have I been scammed! $\endgroup$
    – user6760
    Commented Nov 28, 2019 at 1:23
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    $\begingroup$ Detecting the direction of magnetic north and magnetic south is essentially the same process, and not especially difficult. However, detecting the "relative distance to both" is whole magnitudes more complex and difficult. You seem to want creatures who could, with a little training, not get lost at sea. Real Polynesians, without this extra magnetic sense, have reliably navigated across the Pacific merely using the sun and stars for millennia. $\endgroup$
    – user535733
    Commented Nov 28, 2019 at 1:38
  • $\begingroup$ Downvoting because the asker doesn't fully understand the issue seems a little petty. There's nothing intrinsically wrong with the question itself. $\endgroup$ Commented Nov 28, 2019 at 9:13
  • $\begingroup$ it's actually an essential element of the worldbuilding which affects thousands of years of history. small elements can have massive effects $\endgroup$
    – skout
    Commented Nov 28, 2019 at 15:00

1 Answer 1


Compasses don't detect North, they align to the field.

This is a very important point - the needle in a compass is merely a magnet that sits inside the magnetic field of the earth, and those two fields interact. One of the key attributes of a compass is not the magnet, but the suspension of the magnet in a medium that allows it to spin very easily. That way, the path of least resistance for the magnet is NOT to stay where it is despite the increase in magnetic resistance, but to actually realign itself to the fields around the earth.

Earth's Magnetic Field

So, a compass is not aligning to North, or even to south, but to the field which runs between the two. In point of fact, if you didn't know which end of your magnet was polarised to north, the needle wouldn't help you any and you would have a 50% chance of heading off in EXACTLY the wrong direction unless you used other clues, like the location of the sun in the sky and whether it was morning or afternoon for the day where you are.

So, your people are not even able to detect either North or South, they can just detect the alignment of the field. Your navigators will have a natural instinct of whether they are travelling in parallel or at some angle to the field they can sense, and they may even have some natural sense as to which pole they are closer to (whether they are in the northern or southern hemisphere). As such, they may be able to determine which direction they should head in given that perception and whether they know themselves to be in the North or the South, but it is important to note that in navigational terms, a compass is only one of a handful of tools that a good navigator needs.

Sextants have been around for hundreds of years to determine latitude, and a good spring based clock (pendula don't work on boats) was needed to solve the problem of longitude. All the compass tells you is your orientation, not where you are. So your people need one less tool to determine where they're headed, but they will still need navigational skills to figure out where they actually are.

  • $\begingroup$ I have been researching how compasses work myself, and it seems that all the information I am finding is contradicting you. There is, in fact a needle that does point to magnetic north, but not to true north, and it is worse the closer you get to the poles. However, from what I am seeing, they should be able to know magnetic north and south with two "needled" that point to either pole. $\endgroup$
    – skout
    Commented Nov 28, 2019 at 15:04
  • $\begingroup$ @skout I agree that compasses point to magnetic north, not 'true' north, or the axis of spin and we are lucky on Earth that the two are so closely aligned. But, if the magnet in your compass is not a needle per se, the field of the magnet will still align to the Earth's magnetic field and so long as you know where the poles are for your magnet, you can still read North. The point is, compasses point to magnetic north because that's the way the magnet aligns to the Earth's magnetic field with the minimum of resistance. And as such, every compass needle ALSO points to magnetic south as well $\endgroup$
    – Tim B II
    Commented Nov 28, 2019 at 23:05
  • $\begingroup$ B II I thought that a magnet is attracted to a pole of the opposite type. "North poles" are attracted to "south poles" and vice versa. Because of that, if a compass has a needle that's a "south pole", it will only point to the planetary magnetic north pole. You would require a compass that is a "north pole" to poimt to the south pole. $\endgroup$
    – skout
    Commented Dec 10, 2019 at 17:19

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