Quick Answer
A map's magnetic north reference point deviates from true north due to the Earth's magnetic field variations. Without orienting to true north, a map's accuracy can be off by several degrees, making navigation more challenging.
Understanding Magnetic Variation
Magnetic variation, also known as declination, is the difference between true north and magnetic north. This discrepancy arises from the Earth’s magnetic field’s uneven distribution. The magnetic field lines do not align with the Earth’s rotational axis, causing a variation between true and magnetic north. In the United States, magnetic variation ranges from 10 to 20 degrees, with some areas experiencing up to 30 degrees. Knowing this variation is crucial for accurate navigation.
Orienting Maps to True North
To orient a map to true north, you need to account for the magnetic variation specific to your location. Check a map or a compass for the local magnetic variation. Then, apply the variation to your map by rotating it accordingly. For instance, if the magnetic variation is 15 degrees east, you would rotate your map 15 degrees to the west to align it with true north. Some compasses come with a declination adjustment feature, allowing you to set the local variation directly on the compass. This ensures that your map is accurately oriented to true north, making navigation more reliable.
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