On September 18, 2026, the Earth-facing side of the sun showed no numbered sunspot regions at all, the first time that had happened since February 24 of the same year. The next day it happened again, making it two spotless days in a row and the fourth spotless day of 2026 overall.
Solar astrophysicist C. Alex Young, associate director for science in the Heliophysics Science Division at NASA’s Goddard Space Flight Center, tracked both blank-faced days using images from NASA’s Solar Dynamics Observatory. A pair of unnumbered regions near the solar limb had been firing off weak flares, he noted, but neither one had grown organized enough to earn an official designation before the sun’s rotation carried them out of view.
What “spotless” means, officially
A spotless day isn’t a subjective call. NOAA’s Space Weather Prediction Center explains that the official daily and monthly sunspot counts are calculated by the World Data Center for the Sunspot Index and Long-term Solar Observations at the Royal Observatory of Belgium, using a formula in which each sunspot group counts as 10 and every individual dark core within a group adds one more. Under that system, a day with genuinely no visible sunspots is recorded as zero; the next possible nonzero value is 11, since even a single small group already carries a base score of 10 plus its one spot.
By that standard, EarthSky’s daily sun-activity log confirmed September 18 as the first officially spotless day since February 24, 2026, and September 19 as a second consecutive one. Amateur observer Victor Rogus, photographing the sun from Sedona, Arizona, described the disk that morning as blank apart from a single fading sunspot group that had already begun rotating off the sun’s western limb, adding that its disappearance would mark the year’s fourth spotless day, the most in more than five years.
A peak that came in far hotter than forecasters expected
The current lull follows a solar maximum that overshot its own prediction by a wide margin. The panel of forecasters convened by NOAA, NASA and the International Space Environmental Services in 2019 to forecast Solar Cycle 25 expected a peak smoothed sunspot number between 105 and 125. The actual cycle came in far above that band: the Royal Observatory of Belgium’s solar influences data center confirmed Solar Cycle 25 reached its maximum smoothed sunspot number of 160.8 in October 2024, roughly 35 points above the top of the panel’s original range.
That overshoot is part of why the current run of blank days stands out. A cycle that peaked higher than expected produced more large, complex, flare-prone sunspot groups through 2024 and into 2025, which makes a stretch with none at all a more visible marker of how far the cycle has already fallen from its high point.
The decline is real, but it isn’t fast
None of this means the sun is approaching solar minimum imminently. SWPC’s solar cycle progression page notes that Solar Cycle 26 isn’t expected to begin until sometime between January 2029 and December 2032, meaning Cycle 25 has years of gradual decline still ahead of it before the next cycle’s higher-latitude, opposite-polarity sunspots start to emerge. Spotless days like the ones recorded this week are early, intermittent signals of that decline rather than evidence the cycle has already bottomed out.
The mechanics behind the count itself go back further than either agency’s forecasting effort. NOAA’s own sunspot-cycle explainer traces the numbering convention to Solar Cycle 1 in 1755, and notes that a new cycle is only declared once sunspots begin emerging at higher solar latitudes with reversed magnetic polarity compared with the outgoing cycle, the same marker scientists will eventually use to confirm Cycle 25 has ended. Solar Cycle 24, the one before this one, ran from December 2008 to December 2019 and peaked in April 2014, giving Cycle 25 a rough historical yardstick for how a full decline plays out.
Images of the blank sun this week came from NASA’s Solar Dynamics Observatory, launched in 2010 as the first mission in the agency’s Living With a Star program. The spacecraft photographs the sun in ten ultraviolet wavelengths roughly every twelve seconds, and its inclined geosynchronous orbit was chosen specifically to allow nearly continuous viewing through a single dedicated ground station, which is why the spotless call on September 18 and 19 could be confirmed from one uninterrupted image record rather than pieced together from separate observatories.
Sunspots themselves are not holes or blemishes but regions where intense magnetic flux pushing up from the solar interior suppresses the normal flow of heat, leaving areas roughly 7,000 degrees Fahrenheit sitting inside a photosphere that otherwise runs near 10,000 degrees. That temperature difference is what makes them look dark by comparison, and it is also why sunspot groups, not the number of days without them, remain the primary indicator forecasters use to track where a solar cycle stands. A spotless day simply means that indicator briefly read zero, not that the underlying magnetic activity driving the cycle has stopped.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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