Definition
The two points on the Earth's surface where the planet's magnetic field lines are vertical, meaning a freely suspended magnetic needle points straight down. These points are located near, but not at, the geographic North and South Poles, and they slowly drift over time.
Plain English
The two spots on Earth where a compass needle wants to point straight down into the ground rather than along the surface. They are close to the true North and South Poles but not in the same place.
Context Anchor
Seen in discussions of magnetic compass use, magnetic north, and the difference between true direction and magnetic direction.
Derivation
From Latin magneticus (relating to a magnet) and polus (an end of an axis). The magnetic poles are the 'ends' of the Earth's magnetic axis, which is tilted relative to its geographic spin axis.
Why Pilots Care
The offset between magnetic and geographic poles creates variation that must be corrected for accurate headings and courses.
Analogy
Think of Earth like a very large magnet. The magnetic poles are like the two ends of that magnet, even though they are not in exactly the same places as the map poles.
Grounding Statement
The magnetic poles generate the global field that makes a compass needle point roughly north.
Intuition Check
Magnetic poles are not the same thing as the geographic North and South Poles. They are magnetic areas that move slowly, and they are what a compass responds to.
Example Sentence 1
Because the magnetic poles are offset from the geographic poles, pilots apply variation to convert true course to magnetic course.
Example Sentence 2
Compass errors increase as the aircraft approaches the magnetic poles where the field lines become vertical.