A solar storm can shift your GPS position by several meters even though nothing on the ground has actually moved.
This is what happened in North America during the strong geomagnetic storm of November 11, 2025. Researchers revisited the measurements recorded during the event. They found horizontal errors exceeding 10 meters in some areas. The phenomenon extended across a large portion of the continental United States.
Smartphone displaying Google Maps
Unsplash illustration
To understand this shift, we need to look far above the navigation satellites. GPS signals pass through the ionosphere before reaching our receivers. This region of the upper atmosphere contains electrically charged particles. Their distribution can change dramatically when solar activity disturbs Earth's magnetic field.
During the storm, the region where auroras usually occur shifted southward. Energetic particles then penetrated the atmosphere across an unusually vast area. The amount of electrons in the ionosphere became highly irregular, with strong variations from one location to another.
These irregularities disrupted the radio waves sent by the satellites. Their intensity varied rapidly before reaching the ground. Specialists refer to this as ionospheric scintillation. This phenomenon is well known near the poles and the equator, but it is usually much less pronounced at mid-latitudes.
This time, the researchers detected strong disturbances across thousands of kilometers. They combined cameras observing auroras with numerous satellite navigation receivers in the United States and Canada. The signal variations followed the intensification of disturbances in the ionosphere and the decline in positioning accuracy.
A 10-meter error does not necessarily prevent a driver from following a road on their phone. It can, however, become problematic for applications that require a highly precise position. Automatically guided agricultural machines, certain surveying tasks, and automated navigation systems may depend on meter-level accuracy, or even better.
The extent of the phenomenon is the study's notable finding. Strong scintillations had already been observed at mid-latitudes, but across more limited areas. In November 2025, they affected a broad portion of the United States, almost from coast to coast according to the different measurements used.
The researchers now want to better predict where these disturbances will appear during the next major solar storms. This notably requires tracking the expansion of auroras and the rapid changes in the ionosphere. Improved forecasts could allow activities dependent on highly precise GPS to temporarily anticipate signal degradation.