As the sun approaches its solar maximum—the point at which its roughly 11-year cycle peaks in activity—it has been getting stronger over time.
Space claims that the frequency and intensity of surface-based visible sunspots, which are triggered by the sun’s magnetic field, are markers of a solar activity cycle.
However, it will take experts at least seven months to ascertain whether the solar maximum has indeed happened. We asked the Space Weather Coordination Centre (SSCC) of ESA’s solar expert centre why this is the case.
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In an email to Space, Solar Expert Center scientists stated, “The maximum is computed (as a convention) with the 13-month smoothed sunspot number (which means that for each month you use the value of six months before and six months after).” “The exact value of this quantity for time T is known only 6 months later.”
Because scientists only know whether the sunspot numbers in the following month are lower, it is difficult to tell whether the solar maximum was reached earlier than seven months after this decline starts.
Let’s say, for example, that February 2024 was the date of the solar maximum. Sunspot number data for the six months leading up to February 2024 and the next six months ending in August 2024 would be needed by researchers.
As a result, we would be unable to declare with confidence that the solar maximum took place between February and September of 2024.
According to ESA’s solar experts, the sun can trick us sometimes; even when we think we have achieved a solar maximum, the increased activity turns out to be only a local high, not representative of the entire cycle.
A “double maxima,” sometimes called a Gnevishev’s gap, can also occur in sunspot cycles. In this scenario, the first peak might not be the highest, and a second, bigger peak might follow.
