# The earth’s magnetic north pole is shifting at a speed of about 30 mph. How does GPS remain accurate while the north pole continues moving?

118 views

The earth’s magnetic north pole is shifting at a speed of about 30 mph. How does GPS remain accurate while the north pole continues moving?

In: 0

GPS relies upon triangulation with the position of several satellites relative to your position to work out where you are the relative position of the north pole is largely irrelevant to GPS.

The satellites that broadcast the signals that your GPS device triangulates (essentially) do _not_ shift around like the Earth’s magnetic field. They’re up in space, nothing to affect them in orbit outside of space debris or natural orbit decay (but by the time any of them drift out of orbit really, they’ll be replaced anyway). The physical North Pole of the planet that _their_ coordinate system refers to doesn’t move.

The Earth’s magnetic field is created by all the gooey molten iron in the Earth’s core; its not of consistent composition and it keeps moving around, so the net magnetic field it produces moves as the molton core moves and changes.

GPS uses satellite data; and points to the Physical North Pole.

even though the Magnetic pole is moving the physical pole is not.

GPS in itself is based around the geographic poles rather then the magnetic poles. And these are assumed to be stationary which is good enough. Your GPS receiver might however show a magnetic pole and its position is calculated with a model for how the magnetic poles are shifting.

GPS and Magnetic North have nothing to do with eachother. GPS and other navigational aids use True North, which remains fixed at the physical North Pole (the point where the axis or rotation runs through).

GPS relies on some clever math called triangulation. To prevent drift relative to their orbits, the constellation of satellites synchronize with several fixed ground points around the world. None of this relies on magnetic north.

Is it correct? With this speed compass will be useless.

GPS is not based on earth’s magnetic field at all, it is bases on signals from satellites in earth orbit. GPS devices can have a magnetic field sensor to determine the direction they point but is not relevant for determining the position.

There is ways to determine the north without using the magnetic field, gyrocompasses use forces produces when the earth rotates and points to the geographical north pool not magnetic. That has been the standard on larger ships since WWI

If you navigate with magnetic compares the moment of the magnetic poles can be a relevant factor so it where on earth you are and you need to compensate for it. There is maps on the difference of magnetic and true direction

Because of the location of the magnetic poles, the moment in a year has a minimal effect because the long-distance makes the direction change minimal in most places.

This all assumes you have an iPhone.

Put your phone on a stable, level surface. Open the compass app and see what degree it is pointing towards.

Without moving your phone go to settings-> compass and turn on/off “True North” and go back to the compass app.

You will probably notice a few degrees difference between the two.

“True North” is the place we have all agreed upon as the North Pole, and same for the South. These true points are not in the precise same location as the magnetic pole.

As everyone else has explained, GPS is based upon True North. This just helps you experiment with it yourself.