Magnetic Poles vs. Cartographic Poles: Understanding the Migrating Magnetic North Pole on Earth
As the Earth's magnetic north pole migrates, people often wonder how it fits into our cartographic definitions and whether it aligns with the geographic north pole or if there is a discrepancy. This article will clarify these concepts and explain the differences between the magnetic poles and the cartographic poles, focusing on the current migration of the magnetic north pole.
Geographic vs. Geomagnetic Poles: Definitions and Fixed Positions
First, let's distinguish between the geographic poles and the geomagnetic poles:
Geographic Poles: These are the points where the Earth's axis of rotation intersects the surface. They are fixed and do not change over time.
Geomagnetic Poles: These are the points where the Earth's magnetic field lines are perpendicular to the surface. The geomagnetic north pole is currently located in the Arctic Ocean north of Canada, while the geomagnetic south pole is located south of the Antarctic continent.
It's important to note that the geomagnetic poles are in constant motion due to changes in the Earth's magnetic field, which are due to various geological processes. In contrast, the geographic poles remain fixed as the Earth rotates on its axis.
Magnetic Poles and Compass Behavior
A compass needle points towards the Earth's magnetic north pole because the north end of a compass needle is attracted to the Earth's south magnetic pole. This means that when a compass needle is aligned northward, it is actually pointing towards the south magnetic pole. The term 'magnetic north pole' is indeed a bit misleading, as it refers to the point where magnetic field lines are directed downwards, aligning with the Earth's magnetic south pole.
Cartographic Poles: The North and South Poles on Maps
Now, let's explore the concept of cartographic poles, which are the points used in cartography to define the north and south poles of maps and coordinate systems.
The cartographic north pole is typically defined as the geographic north pole, which is the exact point where the Earth’s rotation axis intersects the northern hemisphere's surface. It is also sometimes defined as the geomagnetic north pole, which is the point where the Earth's magnetic field lines are vertical. Similarly, the cartographic south pole is the geographic south pole, which intersects the Earth's rotation axis at the southern hemisphere's surface, or the geomagnetic south pole where the magnetic field lines are vertical.
Conclusion: Aligning Magnetic and Cartographic Poles
While the location of the magnetic poles is always changing due to the Earth's magnetic field's dynamics, the cartographic poles, specifically the geographic and geomagnetic poles, serve as fixed reference points in cartography and geophysics. It is crucial to understand that the magnetic north pole's movement does not affect the fixed reference points used in creating maps or defining coordinates.
Additional Information
Current research on the Earth's magnetic field and the migration of the magnetic poles can be found in various scientific journals and studies. For a more in-depth understanding, you can refer to sources such as those published by National Geophysical Data Center (NGDC) and Government of Canada's Geomagnetic.