- Scientists developed a new method to predict the strength of the Sun's next activity cycle up to seven years before its peak.
- The method uses sunspot numbers at a 'switch-off' point in the solar cycle when extreme space weather abruptly ends.
- An early prediction for Solar Cycle 26 suggests a moderate cycle with sunspot numbers around 100-120, similar to or weaker than the current cycle.
- The prediction will be refined in about two years when Solar Cycle 25 reaches its switch-off point, allowing observations-based forecasts.
- The research was presented at the Royal Astronomical Society's National Astronomy Meeting in Birmingham.
- Professor Sandra Chapman's team used a 'sunclock' to map the Sun's irregular cycles, revealing that extreme space weather switches off at a distinct point.
- The number of sunspots at the switch-off point correlates with the peak sunspot count of the next cycle, enabling longer lead times than previous methods.
- The method successfully predicted that Cycle 25 would be stronger than earlier forecasts, leading to recent historic solar storms and vivid auroral displays.
- The switch-off point coincides with sunspot regions moving below about 15 degrees solar latitude, where differential rotation weakens.
- Researchers hope this improves understanding of the solar dynamo, the process generating the Sun's magnetic field.