What is the difference between true north and magnetic north?

• A. True north is geographic north; magnetic north is the direction a compass points due to Earth's magnetic variation; variation must be applied to bearings.
• B. True north equals magnetic north at all locations; variation is zero on equator.
• C. Magnetic north is geographic north; true north is a compass reference.
• D. They are the same and can be used interchangeably without adjustment.

Answer: (A)

True north and magnetic north describe two different reference directions. True north is the geographic direction toward the Earth's North Pole, a fixed point on the globe. Magnetic north is the direction a magnetic compass points, which follows the Earth’s magnetic field and is not located at the geographic pole. The angle between these two directions is called variation (also known as declination), and it varies by location and slowly changes over time.

In navigation you often need to convert between bearings measured from true north and those read by a magnetic compass. You adjust by the local variation: if variation is east, you subtract it from the true bearing to get the magnetic bearing; if variation is west, you add it. For example, a true bearing of 045° with a variation of 10° East becomes a magnetic bearing of 035°. If the variation is 12° West, the magnetic bearing becomes 057°.

So, they are not the same direction, and you can’t use one in place of the other without applying the appropriate variation. The concept also notes that variation isn’t constant everywhere or forever—it changes with location and time, which is why charts provide the current variation for a given area.