Scientists have created a fresh approach to forecast the intensity of the sun’s upcoming activity cycle as much as seven years before its maximum. The technique relies on counting sunspots at a newly recognized transition moment in the solar cycle when the most intense space weather events abruptly cease. Researchers applied this approach to produce an early estimate for Solar Cycle 26.
An initial forecast indicates a moderate Cycle 26, with a sunspot count near 100 to 120, comparable to or slightly below the present Cycle 25. Precise forecasts will require another two years of data, although weaker or stronger outcomes remain possible in theory.
The findings were shared this week at the Royal Astronomical Society National Astronomy Meeting in Birmingham. Sandra Chapman, a physics professor at the University of Warwick, noted that the sun does not ease gradually into a quiet phase and then slowly resume activity. Instead, the most extreme space weather ends abruptly at a defined stage in each cycle. Identifying this stage offers a new route to anticipate the activity level of the following cycle.
Chapman expects to update the forecast in roughly two years, once Cycle 25 reaches the transition point and direct observations replace projections. The sun follows an 11-year pattern in which its magnetic field reverses and sunspot numbers rise and fall. Sunspots mark areas of strong magnetic fields that can trigger solar flares and mass ejections, producing space weather capable of disrupting satellites, communications, navigation, and power systems.
Although sunspot records span centuries, cycles differ in length and strength, complicating predictions. The new method extends an earlier sunclock model that aligns irregular solar cycles with a standard clock face. This model showed that extreme space weather does not taper off slowly but stops at a clear point each cycle. The number of sunspots at that point correlates closely with the peak count in the next cycle, enabling forecasts six to seven years before maximum and extending the lead time beyond current techniques that wait for solar minimum.
The approach also marks a stage when the magnetic field driving the next cycle should form. The team hopes the insight will advance understanding of the solar dynamo. Chapman stated that the switch-off point for Cycle 25 lies about two years ahead. Current estimates rely on projections, but once the point arrives, observations alone will yield a sharper prediction for Cycle 26, still providing roughly seven years of advance notice.
The method correctly anticipated that Cycle 25 would exceed many earlier expectations, leading to notable auroral displays. The United Kingdom recorded several notable solar storms during this period.
