Do spheres have poles? Couldn’t any point on a sphere be a pole and the point directly opposite to it be the other pole? If they don’t have intrinsic poles, are Earth’s poles human-defined?

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Do spheres have poles? Couldn’t any point on a sphere be a pole and the point directly opposite to it be the other pole? If they don’t have intrinsic poles, are Earth’s poles human-defined?

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A sphere only has poles if it is rotating. The poles are the spots that ‘don’t move’ during rotation. If you can control the rotation entirely (like a ball in your hand) you can pick any spot as being the poles by adjusting the rotation accordingly. We cant change the way Earth rotates, so the poles remain the same

Yeah any point *could* be the pole but they are defined by the rotation; it’s the two points where the axis meets the surface of the sphere, or the points that, if you were stood there, you wouldn’t move and you just spin in place – If you were to spin the sphere differently then the poles (these special places where you don’t move and just spin) will be in a different place.

> Do spheres have poles?

No

> Couldn’t any point on a sphere be a pole and the point directly opposite to it be the other pole?

Yes

> If they don’t have intrinsic poles, are Earth’s poles human-defined?

Yes. And human defined 2 different pairs of poles: geographic and magnetic

https://en.wikipedia.org/wiki/North_Pole

https://en.wikipedia.org/wiki/North_magnetic_pole

and they have different locations

A spinning sphere has poles on the axis of rotation. On Earth these are usually called the geographic poles.

A magnet also has two poles.

On the Earth, the geographic poles and the magnetic poles are in *almost* the same place, and in casual usage we treat them as the same. Nicer compasses actually let you specify the difference, so that you can use the magnetic pole to find the geographic pole.