What term describes the difference between true north and magnetic north?

The term that describes the difference between true north and magnetic north is magnetic variation. This variation results from the fact that magnetic north and true north do not align perfectly due to the inconsistencies in the Earth's magnetic field.

Understanding magnetic variation is crucial for navigation, especially for pilots, as it allows them to accurately convert between true headings (based on Earth's geographic poles) and magnetic headings (based on the magnetic poles). The difference is expressed in degrees and can vary depending on geographical location and changes over time due to shifts in the Earth's magnetic field.

Navigators typically obtain variation information from aviation charts, which provide the necessary details to ensure that headings are correctly adjusted for accurate course planning and navigation. This helps in avoiding navigation errors caused by discrepancies between magnetic and true headings.