magnetic declination
A compass needle points slightly east of true north due to magnetic declination.
Noun: The angular difference, measured in degrees, between the direction of magnetic north (the direction a compass needle points) and true north (the direction along the Earth's surface towards the geographic North Pole). This angle varies depending on the observer's location on Earth and changes slowly over time.
Magnetic declination is a critical concept in navigation, cartography, and surveying. It is used to convert between a magnetic bearing (read from a compass) and a true bearing (relative to the geographic grid on a map). - When using a map and compass together, you must apply or account for the magnetic declination to navigate accurately. - The declination value is often printed on topographic maps in the map's margin.
- Noun:
- Before starting the hike, we checked the map's legend to find the local magnetic declination, which was 12 degrees west.
- The pilot adjusted the aircraft's course to compensate for the magnetic declination in that region.
- Surveyors must always consider magnetic declination when recording property boundaries based on old deeds that used magnetic directions.
- Declination Diagram: A small diagram on a map showing the relationship between true north, magnetic north, and grid north (the north direction of the map's grid lines). It visually represents the magnetic declination.
- Isogonic Line: A line on a map connecting points of equal magnetic declination. The agonic line is the specific isogonic line where the declination is zero (magnetic north and true north align).
- Magnetic Variation: A synonym for magnetic declination, commonly used in aviation and maritime contexts.
- Declination (in this context): Often used as a shortened form of "magnetic declination."
- Compass Adjustment: The process of setting a compass to account for the local magnetic declination.
- Magnetic variation
- Declination (context-dependent)
- "East declination" or "West declination": Specifies whether magnetic north lies to the east or west of true north from the observer's position. For example, "a declination of 10° E" means magnetic north is 10 degrees east of true north.
- "Applying the declination": The act of adding or subtracting the declination value to a compass reading to find the true direction.
A compass needle points slightly east of true north due to magnetic declination.
- the angle (at a particular location) between magnetic north and true north