Every scout knows how to read a compass, and that there is a magnetic north and a true north. That’s because the Earth’s magnetic field isn’t exactly aligned with the North Pole. Every five years, the US National Oceanic and Atmospheric Administration (NOAA) and the British Geological Survey (BGS) get together to decide if magnetic north is still the same as it was before. This time, it isn’t.

The update is to the WMM — the World Magnetic Model. Magnetic north has shifted away from Canada and towards Siberia, a trend that has been ongoing for the last 20 years.

The magnetic pole seems to be decelerating. It is possible that it can change abruptly enough to warrant an emergency update outside the normal five-year cycle. The BGS says if you traveled from South Africa to the UK using the old WMM, your final position would be about 150 km off compared to using the new WMM.

Of course, automated systems will get updates, so there is no need to adjust your phone or GPS unit manually. However, older gear or compasses are getting increasingly less accurate. The North Star, by the way, isn’t exactly to the North, either. For small trips, being a little off of true north probably isn’t an issue.

There have been emergency updates before. While a basic compass is simple to make, that shouldn’t stop you from overcomplicating it.