The Sun is now at the most active point in its roughly 11‑year solar cycle, and scientists say the current peak has arrived earlier and more forcefully than first expected. As activity climbs, structures that look like vortices in the outer atmosphere point to a corona capable of sending bursts of energy and particles across the solar system.
This article first traces how official forecasts for Solar Cycle 25 evolved, then examines a vortex‑like pattern in the Sun’s atmosphere that resembles a rolling storm front. Together, these threads portray a star that behaves less like a smooth, predictable engine and more like a system with shifting, hard‑to‑model rhythms.
Solar maximum officially declared
On 15 October 2024, a joint Solar Cycle Prediction Panel convened by NASA and NOAA announced that the Sun has entered the maximum phase of its current 11‑year cycle. In an official heliophysics update, the agencies confirmed that the rise in activity that began earlier in the 2020s has now reached the high‑activity period known as solar maximum, when sunspots, flares, and eruptions become more frequent, according to a NASA summary. The wording describes a “maximum phase” rather than a single spike, because this part of the cycle usually stretches across several years instead of one sharp peak.
That same day, NASA’s Goddard Space Flight Center held a teleconference to explain the evidence behind the decision. A visualization record in the Goddard archive links the announcement to Tuesday, 15 October 2024, and notes that NASA and NOAA formally stated that the Sun has reached the maximum period in Solar Cycle 25. That timestamp marks the point when operational agencies began treating maximum as a current condition, with direct consequences for satellite operators, power grid planners, and anyone who follows space weather alerts.
How forecasts shifted toward an earlier peak
The path to this maximum was not straightforward. In late 2019, an international panel co‑chaired by NOAA and NASA released a consensus forecast for Solar Cycle 25 through an official space weather bulletin. Using data available at that time, the panel projected that the cycle would reach its peak around July 2025, with an uncertainty of plus or minus eight months, and expected a smoothed sunspot number of 115 for that peak, according to a NOAA bulletin. That value is a dimensionless index that averages sunspot counts over several months, and it was also adopted in the agency’s operational Solar Cycle Progression product as the target for the height of Solar Cycle 25.
As new observations arrived, the original outlook began to look cautious. An experimental update from the same space weather center later called for a quicker and somewhat stronger peak, shifting the expected maximum for Solar Cycle 25 into a window between January and October 2024, based on an updated forecast. The Solar Cycle Progression charts, which plot observed sunspot counts against the forecast line, still show the 115 target for the smoothed peak, but the narrative about timing moved earlier. The October 2024 declaration that maximum has already arrived fits within that later forecast window rather than the original 2019 schedule.
Reading the solar cycle’s “heartbeat”
Behind those shifting dates is a pattern that looks simple on paper but is hard to predict in detail. Solar cycles are tracked with indices such as the smoothed sunspot number, which averages visible dark spots over time to filter out short‑term ups and downs. The official Solar Cycle Progression page kept by NOAA’s space weather center plots those values for Solar Cycle 25 and overlays a forecast curve that climbs toward a peak of 115, giving researchers and operators a shared view of where the Sun sits along its 11‑year “heartbeat” curve. On that chart, observed monthly sunspot numbers rose from values near 40 early in the cycle to higher counts such as 62 and 85 as the maximum phase approached, and some recent months have reached levels around 698 when summed across the dataset, underscoring how active the surface has become.
The October 2024 maximum call suggests that the main change has been in timing rather than in the expected height of the cycle. The 2019 consensus already allowed a broad July 2025 peak window with eight months of uncertainty, and the later experimental update explicitly moved that window into 2024, so the declaration falls inside the evolving forecast envelope described in a panel summary. Earlier cycles also show this kind of variability: Solar Cycle 23, for example, followed its own timing and amplitude pattern, which forecasters now use as one of several historical guides when they compare the current cycle’s 115‑sunspot prediction with past behavior.
Vortex-shaped storms in the corona
While the cycle plots reveal the long‑term rhythm, the Sun’s corona shows the fine‑scale structure of that activity. One striking feature in the outer atmosphere was recorded by NASA’s Solar Dynamics Observatory, whose Atmospheric Imaging Assembly instrument captured vortex‑shaped structures that behave like giant atmospheric waves. In a public preprint archived as arXiv:1101.4249, lead authors Leon Ofman and Barbara J. Thompson describe how SDO’s imaging system observed a Kelvin‑Helmholtz instability rolling along the edge of a solar eruption, forming a chain of swirling “billows” that resemble storm clouds at the boundary between two moving layers, as detailed in their preprint. The arXiv identifier 1101.4249 is now often used as shorthand among solar physicists when they discuss this type of vortex event in the corona.
These vortices are more than just dramatic images. A Kelvin‑Helmholtz instability appears when two layers of fluid or plasma slide past one another at different speeds, and in the solar corona that shear flow can signal strong magnetic and velocity gradients at the edge of a coronal mass ejection. Ofman and Thompson’s analysis of the SDO data shows that vortex‑shaped coronal features can grow and persist along that boundary, which means the interface between ejected plasma and the surrounding corona is not smooth in the event documented under arXiv:1101.4249. During solar maximum, when eruptions occur more often, conditions for similar instabilities are expected to be more common as well, although the available sources do not yet provide an official count of how many such events have taken place in Solar Cycle 25.
What a “wild” maximum really means for Earth
Taken together, the forecasts and observations point to a solar maximum that is energetic but still within the range that official documents anticipated. The Prediction Panel’s expectation of a peak smoothed sunspot number of 115, recorded in the Solar Cycle Progression dataset and related summaries, sets a statistical backdrop for this period: more active regions on the surface, more flares, and more chances for eruptions that could be directed toward Earth. The October 2024 declaration that the Sun is now in the maximum phase means that the odds of geomagnetic storms will stay elevated for several years, but the sources do not specify how many of those storms will reach strong or extreme levels.
The vortex events highlight how complex the corona becomes under these conditions, but they should be interpreted with care. It is reasonable, based on plasma physics, to suggest that a corona filled with Kelvin‑Helmholtz‑type instabilities reflects a highly stressed magnetic environment, and such conditions may be linked to complicated eruptions. However, neither the Ofman and Thompson preprint nor the official solar cycle forecasts claim that these vortices directly increase the number of Earth‑directed storms in Solar Cycle 25. The available sources do not show that this maximum will produce twice as many dangerous events as earlier expectations; instead, they describe a cycle whose timing and detailed structure differ from early estimates while still matching the general strength that agencies built into their 115‑sunspot prediction.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
