What you see in the sky
Auroras occur when charged particles are channelled into the Earth's atmosphere and cause gases there to glow. Frequent triggers are coronal mass ejections (CME), plasma clouds from the sun that can hit the earth after one to three days. The luminous gases become visible when the geomagnetic activity is strong enough and it is dark. It is important to categorise them: the aurora is not the "solar storm" itself, but the visible sign that the Earth's magnetic field is currently being strongly stimulated.
When auroras are visible in Germany, this is a clear indication of increased geomagnetic activity. This week, the event was temporarily categorised as G4 on the G-scale (levels G1 to G5 for geomagnetic storms). G4 is considered strong.
By the way: These processes take place all year round. It is a myth that auroras only occur in winter. They are always there, but they are not always visible. They only become visible when the sky is dark enough. On bright summer nights, the activity can be present without being visible to the naked eye.
What dangers arise
However, there is no acute, direct health risk for water sports enthusiasts. This only affects people who are outside or on the edge of the Earth's natural protective shield, such as astronauts or flight personnel due to increased radiation exposure. Rather, the dangers are more secondary, resulting from possible malfunctions of technical systems, especially during demanding navigation, at night or offshore.
For example, GNSS satellite navigation (GPS, Galileo) can become less accurate during periods of high activity. This is caused by the altered ionosphere, which influences the signalling paths. This can manifest itself as greater position dispersion, brief dropouts or implausible jumps. Short-wave radio (HF) can also be more severely affected because it is also dependent on the ionosphere. VHF marine radio is not usually affected in everyday coastal life because VHF is predominantly a visual radio. However, interference can never be completely ruled out.
The compass or other magnetic sensors, such as fluxgate sensors, can also be disturbed, as magnetic field fluctuations can increase during geomagnetic storms. In practice, this means that course indications can become more erratic and a small deviation can be annoying at the wrong moment, for example when navigating at night or in narrow waters. However, in our latitudes, these deviations tend to be in the range of Deviation.
Correct behaviour during solar storms
An aurora borealis is no reason to flee to harbour. But it is a good reason to review your own navigation discipline, especially if you rely heavily on electronics.
Sensible precautions when the space weather warning level is high or navigation becomes challenging (and which should always apply anyway):
- Check the plausibility of the GNSS position: Actively use radar, bearings, depths, buoy image and log/sounder for cross-checking instead of just following the plotter point.
- Compare course sources: Magnetic compass, electronic compass, course over ground from GNSS. In the event of deviations, navigate conservatively and correct earlier.
- Think communication redundant: Anyone travelling offshore or using shortwave should plan alternatives in the event of strong events.
- Timing: Narrow areas, night, strong winds and lots of traffic are "error amplifiers" anyway. If technology becomes even more unreliable, a conservative plan can make sense.
Where can I get information?
Websites
- GFZ Potsdam: The GFZ (Helmholtz Centre for Geosciences, Potsdam) publishes the Kp index (planetary K index, measure 0 to 9 for geomagnetic activity) and explains its meaning. (kp.gfz.de)
- Met Office Space Weather: The Met Office (British weather service) also provides situation reports and warnings. (Met Office)
Apps (selection):
Apps are particularly useful for everyday life on board if they provide push alerts and present the most important key figures in an understandable way.
- SpaceWeatherLive (iOS/Android): Displays space weather data and aurora chances, including push notifications for events such as flares and geomagnetic storms.
- My Aurora Forecast & Alerts (iOS/Android): Focus on visibility probability, Kp value and maps, including push alerts for high activity.
- Aurora Alerts (iOS/Android): Also designed for notifications and real-time activity, with alerts when Northern Lights are possible.
- Solar Monitor 3 (iOS): More technically orientated, with a live alert system and diagrams on solar wind, X-ray flux and Kp, interesting for readers who want to delve deeper.
Summarised
Auroras are first and foremost beautiful and pose no immediate danger. However, you should pay particular attention when strong solar storms are forecast.
