The angle between the magnetic meridian (the direction indicated by a magnetic compass needle) and the geographical meridian (the direction of true north-south as determined by the Earth's rotation axis) is known as the magnetic declination or magnetic variation.
Magnetic declination varies depending on the location on the Earth's surface and changes over time due to fluctuations in the Earth's magnetic field. This angle is crucial for navigation and orienteering, as it helps correct for the difference between magnetic north (the direction a compass points) and true north (the direction towards the North Pole).
In navigation, it's essential to adjust compass readings by the magnetic declination to determine true directions accurately. Maps and navigation tools often provide information about the local magnetic declination to ensure accurate navigation, especially in areas where the difference between magnetic north and true north is significant.
