What is meant by magnetic declination?

Magnetic declination refers to the angle between true north, which is the direction along the Earth's surface towards the geographic North Pole, and magnetic north, which is where a compass points. This angle can vary based on geographic location and fluctuates due to changes in the Earth's magnetic field.

Understanding magnetic declination is crucial for navigation and map reading because it allows users to correct compass readings to find true north. For instance, if you are using a compass in an area with a known magnetic declination, you would adjust your bearing accordingly to ensure accurate navigation.

The other options, while related to navigation and orientation, do not accurately define magnetic declination. For example, the angle of the compass needle pertains to how the compass functions but not specifically to the alignment between true and magnetic north. Likewise, the difference between true north and grid north applies to map projections and is important for mapping purposes, but it does not address magnetic north. The variation in map scale relates to how distance is represented on a map and is not relevant to magnetic declination. Understanding these distinctions helps in effectively using navigational tools and maps.