What is the term used for the difference between magnetic north and true north?

The term that describes the difference between magnetic north and true north is magnetic declination. This angle plays a crucial role in navigation and surveying as it indicates how much a compass needle deviates from true north due to the Earth's magnetic field.

Understanding magnetic declination is essential for land surveyors and navigators because it allows them to correct their compass readings to ensure accuracy in mapping and positioning. By factoring in the declination, surveyors can align their findings with true geographic coordinates, which is vital for legal land descriptions, boundary determinations, and related tasks.

In practice, magnetic declination varies by location and over time, necessitating up-to-date information for accurate calculations. Mapping and navigation resources often provide this critical data to help users make necessary adjustments when interpreting compass readings.