What is Magnetic Declination?
Magnetic declination is sometimes referred to as the magnetic variation or the magnetic compass correction. It is the angle formed between true north and magnetic north. Declination varies from 0 to 30 degrees in most populated regions of the world. These declination values usually change slightly over time, as the earths plates shift. By convention, declination is measured positive east and negative west (i.e. declination of -6 means 6 degrees west of north). A magnetic declination of 12 degrees West means that magnetic North lies 12 degrees West of true North. sunPATH can make Sun calculations taking into account the Magnetic Declination of a location, allowing you to use your compass without any corrections.
The elements iron, nickel and cobalt possess electrons in their outer electron shell, although the next inner shell is not filled. Their electron “spin” magnetic moments are not canceled, thus they are known as ferromagnetic. Iron is especially abundant in the universe, since it is the final unburnable stellar nuclear ash. These dense elements sank to the core of the molten Earth as it accreted from a nebula of exploded stars. Earth’s core has remained molten due to heat from ongoing radioactive decay. Convection currents flowing in the outer core generate a magnetic field, but the poles of this field do not coincide with true north and south–the axis of rotation of the Earth. In mid 2002, the average position of the modeled north magnetic dip pole (according to the IGRF-2000 geomagnetic model) is 81.5° N, and 111.4° W, in the Canadian Arctic Ocean. This position is 950 kilometers (590 miles) from the true (geographic) north pole. The geomagnetic field can be quantified as total inten
Many people are surprised to learn that a magnetic compass does not normally point to true north. In fact, over most of the Earth it points at some angle east or west of true (geographic) north. The direction in which the compass needle points is referred to as magnetic north, and the angle between magnetic north and the true north direction is called magnetic declination. You will often hear the terms “variation”, “magnetic variation”, “compass variation” or “march of the compass” used in place of magnetic declination. The magnetic declination does not remain constant in time. Complex fluid motion in the outer core of the Earth (the molten metallic region that lies from 2800 to 5000 km below the Earth’s surface) causes the magnetic field to change slowly with time. This change is known to as secular variation. Unfortunately, the annual change corrections given on most of these maps cannot be applied reliably if the maps are more than a few years old since the secular variation also ch
