For any individual relying on the compass to navigate any area, it is important to understand the magnetic declination, or simply declination, before using these navigation tools. That’s because, in some places, the compass might not give you the direction of the geographic north. It might come as a surprise to you, but it is possible that the compass can point towards the south. Here, the magnetic declination refers to the asymmetrical field, which makes navigation super complex. It is defined as the angle between the actual north and the magnetic north.
It is believed that the compass needle will point you towards the north, on most surfaces. There are also places where the needle will direct you totally towards the north, while on some irregular surfaces, the compass might point you towards the south or a completely opposite pole. There is no denying that the compass needle points you towards the north magnetic pole, but if you follow these instructions, you will not get to the north following the direct route. Let’s see how magnetic declination changes and what causes this change.
Why Does Magnetic Declination Change From Time to Time?
Magnetic declination is never the same. In fact, it keeps changing depending on the time and place. Take the United States, for example. The magnetic declination in the states varies from 20 degrees in Maine to 10 degrees in Texas. So, the declination varies significantly by the place. This clearly shows the importance of adjusting the compass based on where you are using it. If you do not adjust the compass for the particular region, chances are you will get an error of above 30 degrees.
These spatial differences in the regions indicate the asymmetrical surfaces of Earth. It also depends on what’s present deep in the earth. For instance, the iron ore present in the earth’s crust can be a major factor that creates a big difference in the magnetic declination. It is due to the secular variation that the magnetic declination keeps fluctuating from time to time.
Factors Affecting the Change in Declination
The materials present deep in the earth’s crust, the irregularity on the surfaces, and other factors contribute to this significant declination. That is why people using a compass to get the north pole direction are supposed to adjust it to the magnetic declination of the particular area before using it. There are times when the compass might not give the most appropriate direction or it may simply take you through the indirect route.
The best example of the varying magnetic declination is Yellowknife, NWT. Every three years, the region reports a change in the declination by more than one degree. In Ottawa, however, the researchers have reported zero fluctuations in the declination annually. Similarly, the rate and degree of changes in declination vary by state. How much will the user be affected by this fluctuation in the magnetic declination depends on the user’s application, as well as, the location.