What is magnetic declination?

What is magnetic declination?

• A. The angle between geographic north and the north to which a compass needle points.
• B. The angular distance between magnetic north and geographic south.
• C. The velocity of the Earth's rotation.
• D. The strength of the Earth's magnetic field at a point.

Answer: (A)

Magnetic declination is the angle between geographic north (true north) and magnetic north—the direction your compass needle points. This difference exists because Earth’s magnetic field isn’t perfectly aligned with its rotation axis, and it varies by location and over time. Knowing the local declination lets you convert between compass headings and true bearings used on maps and in flight planning, or adjust your navigation system accordingly. The other options describe different ideas: angular distance to the opposite pole, the rotation speed of Earth, or the strength of the magnetic field at a point, none of which define declination.

Magnetic declination is the angle between geographic north (true north) and magnetic north—the direction your compass needle points. This difference exists because Earth’s magnetic field isn’t perfectly aligned with its rotation axis, and it varies by location and over time. Knowing the local declination lets you convert between compass headings and true bearings used on maps and in flight planning, or adjust your navigation system accordingly. The other options describe different ideas: angular distance to the opposite pole, the rotation speed of Earth, or the strength of the magnetic field at a point, none of which define declination.