Do Compass Apps Point to Geographical North or Magnetic North?

When using a compass app on your phone, have you ever wondered whether it points to geographical north or magnetic north? This is an important question because while both types of north serve as important navigational references, they are fundamentally different.

Understanding Geographic and Magnetic North

The Earth has two types of north poles: geographic north and magnetic north. Geographic north is the point located at the top of the Earth, opposite to the south pole, while magnetic north is slightly different due to the Earth's magnetic field. The magnetic north pole moves over time due to the flow of liquid iron beneath the Earth's core, making it a more dynamic reference point.

The Importance of the World Magnetic Model (WMM)

The discrepancy between these two types of north is significant enough in many parts of the world to notice. To address this, compass apps use the World Magnetic Model (WMM). The WMM is a mathematical model that helps align the magnetic north on your phone to the geographical north. It is created and updated every few years by a team of researchers and geologists at the National Oceanic and Atmospheric Administration (NOAA).

How Compass Apps Work

Most modern smartphones have built-in magnetometers and accelerometers. These sensors measure the Earth's magnetic field and the orientation of the device. The simplest compass apps would indicate magnetic north based on this information. However, more sophisticated apps can use GPS and internet connectivity to download tables of magnetic declination. This allows them to automatically adjust and show geographical north instead.

Checking if an App Shows Geographical North

In most areas, it is clear whether an app is showing magnetic north or geographical north. Here are a few ways to verify:

If you have access to Polaris (the North Star), you can estimate if the app is showing true north. However, Polaris is not perfect, but it is close enough for this purpose.

You can also use the position of the sun and your watch if you have set your watch to the correct time.

For those who cannot use these methods, it is recommended to download a few compass apps and see how they differ. Most apps will be quite accurate when showing the correct direction.

Why the WMM Is Critical for Navigation

The WMM is crucial for navigation because inaccuracies can affect a user's location data. For example, without the WMM, your phone might show that you are at geographical north when you are actually at magnetic north, which is currently somewhere on Ellesmere Island in Northern Canada, about 600 miles south of true north.

Recent Developments and Challenges

A new version of the WMM was released in 2015, but it became outdated by March 2018 due to unexpected changes in the Earth's magnetic field. Researchers quickly released an updated version to maintain accuracy.

Interestingly, the movement of the magnetic north pole has been increasing at a faster rate than previously predicted. This suggests a significant change in the Earth's magnetic field and poses challenges for navigation technology.

Conclusion

The discrepancy between magnetic north and geographical north is a complex issue, but modern compass apps have made great strides in addressing this problem. By using the WMM and other advanced algorithms, these apps can provide accurate navigation information. So, whether you are using a simple compass app or a more complex GPS tool, you can trust that it will help you find your way.

Further Reading and Exploration

To dive deeper into this topic, you might want to explore resources related to the Earth's magnetic field, the World Magnetic Model, and navigation technology. Understanding these concepts can provide a richer appreciation of the science behind the apps that we use every day.