News — A consortium of solar science experts declared consensus on the next solar cycle. The cycle, which indicates the intensity and timing of the Sun’s activity, fluctuates every 11 years or so. The cycle is based on the number of sunspots visible on the Sun’s surface over time and changes due to the dynamic magnetic field.
“We came to a consensus that the next solar cycle will be very similar to the last one” explains Dr. Gordon Petrie of the NSF’s National Solar Observatory, who was a member of the consortium. “This is an interesting sign because it might just be the turnaround from the ever weaker solar cycles we have seen since the 1970s and a speculation of a new Maunder minimum when the Sun underwent 70 years, from 1645-1715, of much reduced sunspot activity. The new forecast implies an end to this trend.”
“I’ve noticed by studying magnetic field maps of the Sun covering the past four decades that the arrangement of sunspots has been changing and not been as expected, especially at the end of cycle 23 (2003-2004). Right after these changes, we started to see weakening solar cycles for a few decades,” he said.
The solar cycle plays an important role in understanding how explosive the Sun will be at any given time, which ultimately has an effect on conditions at Earth, a phenomenon known as space weather. This can have an impact on our everyday lives via communication losses, GPS failures and power outages, as well as larger scale impacts such as astronaut safety and the future of space travelers to the Moon or Mars.
The consortium, led by Dr. Douglas Biesecker of NOAA’s Space Weather Prediction Center, and Dr. Lisa Upton of the Space Science Institute reached consensus by evaluating a plethora of academic articles that present a variety of techniques for forecasting the next cycle. “We contemplated a wide range of forecasts,” adds Petrie, “From statistical models, and past cycle observations, to solar cycle precursors and the dynamics of waves that point to future sunspots. We evaluated over 60 academic articles by authors from all over the world.”
The team, which included solar experts with a wide range of skills, debated long and hard on the validity, rigor, plausibility and robustness of these papers, ultimately reaching a unanimous consensus. “Mid 2025 is when we expect this solar cycle to peak,” says Petrie. This means that the number of sunspots will continue to rise from now until the middle of 2025. “It’s hard to pin down a specific date, but we predict that the middle of 2025 is when we’ll have the most sunspots of this cycle. We expect there to be approximately 115 sunspots at the maximum, which is very close to what we saw during the previous cycle, which maxed out at 120 sunspots. This is what tells me that this might be the beginning of a return to stronger solar cycles and break from ever shrinking ones we have seen the past few decades.”
Dr. Petrie is an expert in solar magnetism, and works for the NSO Integrated Synoptic Program, or NISP – a program that has been funded by the National Science Foundation since the mid-1980s. “We believe in the importance of ongoing, long-term studies of the Sun,” says Dr. Alexei Pevtsov, Director of the NISP program at NSO. “Determining the beginning of these cycles helps us better understand the nature of the solar cycle.”
“Because a full solar magnetic cycle takes about 22 years, including magnetic polarity reversal every 11-year sunspot cycle, the continuity of synoptic observations of the Sun through programs like NISP are vital to our understanding of the long-term variations of our closest star,” says David Boboltz, NSF’s Astronomy Program Director for the NSO.
Scientists use sunspots as an indicator of solar activity. The density of sunspots waxes and wanes over an 11-year period. This regular rhythm is called the solar cycle. So what of solar minimum? “Actually, we think we have already passed the depth of solar minimum in December of 2019,” explains Petrie. “It is relatively early in our forecast window, which may indicate a slightly stronger peak this time around.” This means we can hope to see plenty of sunspots, and possibly even some solar eruptions during the next total solar eclipse to cross the continental USA in 2024
“We hope that an eclipse close to solar maximum will not only show us an awe-inspiring corona, but also some big, interesting sunspots on the face of the Sun to help us learn about living inside the atmosphere of an active star and the space weather it creates,” says Dr. Valentin Martinez Pillet, director of the NSO.
For daily observations of the Sun and its sunspots, visit .
You should never look directly at the Sun without proper eye protection; sunglasses won’t cut it.
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