Solar Cycle 25

Scientists charged with predicting the Sun’s activity for Cycle 25 say it’s likely to be much like that of current Cycle 24, which is declining and predicted to bottom out in 2019 or 2020. Solar Cycle 25 Prediction Panel experts said Cycle 25 may get off to a slow start but is anticipated to peak between 2023 and 2026 with a sunspot range of 95 to 130. This is well below the typical average of 140 to 220 sunspots per solar cycle. The panel expressed high confidence that the coming cycle should break the trend of weakening solar activity seen over the past four cycles. The Solar Cycle Prediction Panel forecasts the number of sunspots expected for solar maximum, along with the timing of the peak and minimum solar activity levels for the cycle. The outlook was presented on April 5 at the2019 NOAA Space Weather Workshop in Boulder, Colorado.

“We expect Solar Cycle 25 will be very similar to Cycle 24: Another fairly weak cycle, preceded by a long, deep minimum,” said panel co- chair Lisa Upton, a solar physicist with Space Systems Research Corp. “The expectation that Cycle 25 will be comparable in size to Cycle 24 means that the steady decline in solar cycle amplitude, seen from cycles 21 – 24, has come to an end and that there is no indication that we are currently approaching a Maunder-type minimum in solar activity.”

The solar cycle prediction gives a rough idea of the frequency of space weather storms of all types, from radio blackouts to geomagnetic storms and solar radiation storms. In addition to its effects on Amateur Radio signal propagation, space weather can affect power grids; critical military, airline, and shipping communications; satellites and GPS signals, and can even threaten astronauts through exposure to harmful radiation.

Solar Cycle 24 reached its maximum in April 2014 with a peak average of 82 sunspots. The Sun’s Northern Hemisphere led the sunspot cycle, peaking more than 2 years ahead of the Southern Hemisphere sunspot peak. Given that the Sun takes 11 years to complete one solar cycle, this is only the fourth time that US scientists have issued a solar cycle prediction. The first panel convened in 1989 for Cycle 22.

For Solar Cycle 25, the panel hopes for the first time to predict the presence, amplitude, and timing of any differences between the northern and southern hemispheres on the Sun, known as hemispheric asymmetry. Later this year, the panel will release an official sunspot number curve showing the predicted number of sunspots during any given year and any expected asymmetry. The panel will also look into the possibility of providing a solar flare probability forecast.

“While we are not predicting a particularly active Solar Cycle 25, violent eruptions from the sun can occur at any time,” said Doug Biesecker, panel co-chair and a solar physicist at NOAA’s Space Weather Prediction Center (SWPC). An example of this occurred on July 23, 2012, when a powerful coronal mass ejection (CME) eruption missed Earth but enveloped NASA’s STEREO-A satellite. A 2013 study estimated that the US would have suffered between $600 billion and $2.6 trillion in damages, particularly to electrical infrastructure, if the 2012 CME had been directed toward Earth. The strength of the 2012 eruption was comparable to the famous 1859 Carrington event that caused widespread damage to telegraph stations around the world and produced aurora displays as far south as the Caribbean.