Scientists found a turning point in the sun’s cycle that could forecast space weather years ahead

The Sun runs on an eleven-year rhythm, swinging from quiet stretches to stormy peaks and back again, and forecasting where that cycle is headed has long been one of the harder problems in space science. Getting it right matters well beyond astronomy: the strength of a solar cycle shapes how often satellites, power grids, aviation, and communications face damaging space weather. A team of physicists says it has found a sharp, previously overlooked moment inside each cycle — a kind of switch that flips off the Sun’s most violent activity almost overnight — and that reading the Sun at that instant could predict the intensity of the next cycle roughly six to seven years before it peaks.

The “switch-off” moment hidden in the solar cycle

Space-weather forecasters have traditionally treated the end of a solar cycle as a gradual fade, with activity tapering as sunspot numbers decline toward the minimum. The new work argues that the most extreme events do not wind down slowly at all. Instead, according to the research summarized in a report on the finding, there is a distinct point at which the Sun’s capacity for the most severe space weather shuts off abruptly — a clean cutoff rather than a slope.

That sharp transition is the crux of the discovery. If violent activity ends at a well-defined instant, then the state of the Sun at that moment becomes a meaningful, measurable marker. The team’s central claim is that the number of sunspots present when the switch flips carries predictive information about how strong the following cycle will be, turning a single snapshot into a long-range forecast tool.

The University of Warwick team behind the finding

The research was led by Professor Sandra Chapman of the University of Warwick’s Centre for Fusion, Space and Astrophysics, and the results were presented in late July 2026 at the Royal Astronomical Society’s National Astronomy Meeting held in Birmingham, England. Chapman’s group has spent years analyzing long records of solar activity to find statistical structure that standard cycle-tracking misses.

Their explanation ties the cutoff to the geography of the solar surface. Sunspots migrate toward the Sun’s equator as a cycle matures, and the team proposes that once the active regions crowd within about 15 degrees of the equator — where the Sun’s differential rotation, its tendency to spin faster at the equator than the poles, weakens — the mechanism that drives the largest eruptions effectively switches off. Coverage of how the Sun goes quiet describes this latitude threshold as the physical trigger behind the abrupt end of severe space weather.

How counting sunspots at one instant forecasts the next peak

The forecasting logic follows from the cutoff. Because the switch-off happens at a consistent, identifiable stage rather than smearing out over months, the sunspot count at that stage can be measured cleanly and compared across cycles. The team reports that this number correlates with the strength of the cycle that follows, giving a lead time of six to seven years — long before the next maximum arrives and long before conventional methods can offer a confident prediction.

That lead time is what makes the approach potentially valuable to operators who plan around space weather. Satellite designers, grid managers, and mission planners currently work with cycle forecasts that carry large uncertainties until a cycle is already well underway. A reliable signal delivered years in advance would let those users prepare for a stormy or a mild cycle with more confidence, from hardening equipment to scheduling launches and missions around expected conditions.

The track record that lends the method credibility

A new forecasting idea earns trust by making calls that come true, and the team points to one. Its method indicated that Solar Cycle 25 — the cycle now near or past its peak — would run stronger than several mainstream forecasts had predicted. That call was borne out when a powerful geomagnetic storm in May 2024 drove auroras far outside their usual range, appearing across unusually low latitudes in both hemispheres, a display consistent with a more energetic cycle than the cautious consensus had expected.

For the next cycle, Solar Cycle 26, the group’s early read points to a moderate cycle, with a projected peak sunspot number somewhere in the range of about 100 to 120 — comparable to Cycle 25 or slightly weaker. As detailed in reporting on the new forecasting approach, the researchers caution that a sharper number will not be possible for roughly two more years, and that both stronger and weaker outcomes remain within the range of possibility until more data accumulate.

What better lead time would change for life on the ground

Space weather is not an abstract concern. Coronal mass ejections and solar storms can induce currents that stress power transformers, degrade satellite electronics, disrupt GPS and radio signals, and raise radiation exposure for astronauts and high-altitude flights. Knowing years ahead whether the Sun is trending toward an active or a quiet cycle would let the industries exposed to those hazards budget, engineer, and schedule accordingly.

As with any single study, the switch-off method will need further testing against future cycles and scrutiny from other solar physicists before it becomes part of standard forecasting practice, and its authors frame it as a promising signal rather than a finished operational tool. Still, the appeal is clear in a field where useful predictions have been stubbornly short-range. If the pattern holds up as cataloged in ongoing space and astronomy research, forecasters may gain years of warning about the Sun’s next mood — time that translates directly into resilience for the technology that a modern society keeps in orbit and on the grid.

This article was researched and drafted with the assistance of AI and reviewed before publication.

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