What is the definition of variation in navigation?

Variation in navigation refers specifically to the difference between true north and magnetic north at a particular location. True north is the direction along the earth's surface toward the geographic North Pole, while magnetic north is the direction that a magnetic compass points, which can vary due to the Earth's magnetic field. This difference is crucial for navigators because it must be accounted for when converting between true heading (based on true north) and magnetic heading (based on magnetic north) to ensure accurate navigation.

Understanding that variation can significantly affect course plotting and navigation is essential for mariners and aviators. It allows them to correct their compass readings, which can be influenced by local magnetic anomalies and the natural variation of the Earth's magnetic field. Thus, knowing the variation is vital for ensuring that a vessel or aircraft can reach its intended destination accurately.