Here's why:
* Earth's Magnetic Field: The Earth's magnetic field, which dictates the direction of True North, is constantly shifting and changing. This is due to the movement of molten iron in the Earth's core.
* Magnetic Poles Drift: The magnetic poles (North and South) are not stationary. They drift slowly over time, sometimes by several miles per year. This drift means True North also shifts.
* Magnetic Reversals: Over geological timescales, the Earth's magnetic field can even completely flip, meaning the magnetic North and South poles switch places. These reversals happen very slowly over thousands of years.
So, how do we know where True North is?
We use a model called the World Magnetic Model (WMM) which is updated every five years to account for these changes in the magnetic field. This model helps us determine the current position of True North, though it's important to remember that it's a constantly changing target.
