difference between true north and magnetic north
The Earth’s magnetic field is a crucial element that has been shaping human navigation and exploration for centuries. It is important to understand the difference between true north and magnetic north, as they play a significant role in determining directions. True north refers to the geographical north pole, which is the point where all the Earth’s meridians converge. On the other hand, magnetic north is the point where the Earth’s magnetic field lines converge. Although they are closely related, there are notable differences between the two.
Firstly, true north is an imaginary point on the Earth’s surface, while magnetic north is a physical point. True north is the point on the Earth’s surface where all the meridians intersect, and it is the reference point for geographical coordinates. In contrast, magnetic north is the point where the Earth’s magnetic field lines converge, and it is the point where a compass needle aligns with the Earth’s magnetic field.
The difference between true north and magnetic north is caused by the Earth’s magnetic field being tilted with respect to its rotational axis. This tilt, known as the geographic axis, creates a magnetic declination, which is the angle between true north and magnetic north. The magnetic declination varies depending on the location on the Earth’s surface. In some areas, the declination is close to zero, while in others, it can be as high as 30 degrees.
The magnetic declination can be either positive or negative. A positive declination means that magnetic north is to the east of true north, while a negative declination means that magnetic north is to the west of true north. This variation is important for compass navigation, as a compass needle will point towards magnetic north, not true north. Therefore, when using a compass for navigation, it is essential to account for the magnetic declination to ensure accurate directions.
Another significant difference between true north and magnetic north is the presence of the magnetic north pole. The magnetic north pole is not a fixed point but is instead moving over time due to the dynamic nature of the Earth’s magnetic field. This movement is known as the geomagnetic secular variation. As a result, the magnetic north pole has been shifting eastward at a rate of about 40 kilometers per year. This movement can affect compass navigation, as the compass needle will no longer point precisely towards the magnetic north pole.
In conclusion, the difference between true north and magnetic north is a result of the Earth’s magnetic field and its interaction with the Earth’s surface. True north is an imaginary point on the Earth’s surface, while magnetic north is the point where the Earth’s magnetic field lines converge. The magnetic declination, caused by the tilt of the Earth’s magnetic field, varies depending on the location and can affect compass navigation. Understanding these differences is crucial for accurate navigation and exploration in various fields, including geology, navigation, and surveying.
