Scientists have identified a sudden "switch-off" point in the Sun's 11-year cycle that could allow earlier predictions of future solar activity. The technique uses sunspot counts at this stage to estimate the strength of the next cycle up to seven years ahead. An initial projection indicates Solar Cycle 26 will be moderate.
Researchers presented the findings this week at the Royal Astronomical Society's National Astronomy Meeting in Birmingham. The approach focuses on the abrupt end of the most severe space weather during each cycle, when active sunspot regions move below about 15 degrees solar latitude.
Sandra Chapman, professor of physics at the University of Warwick, said the Sun does not transition gradually. She noted that extreme activity switches off suddenly at a defined point, providing a new predictor for the following cycle's peak.
Early estimates place Solar Cycle 26 at a sunspot number of roughly 100 to 120. This would make it similar to or weaker than the current Cycle 25. A more precise forecast is expected in about two years, once Cycle 25 reaches its switch-off point.
The method previously anticipated stronger activity in Cycle 25, which aligned with notable geomagnetic storms and auroras observed in the UK during 2024.