NASA’s forecast for solar cycle 25 reveals it will be the weakest of the last 200 years.
The ‘Maunder Minimum’ is the name given to the period from 1645 to 1715 when the number of sunspots – ‘storms’ on the sun – became almost zero.
The period is named after the solar astronomer Edward Walter Maunder (1851-1928), who was working at The Royal Observatory at Greenwich when he discovered the dearth of sunspots during this period.
During one 30-year period within the Maunder Minimum there were only about 50 sunspots compared with a more typical 40,000. Maunder was a driving force in the foundation of the British Astronomical Association and a Fellow of the Royal Astronomical Society.
The sun was well observed during the period of the Maunder Minimum and this lack of sunspots is well documented. This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age’ when in Europe rivers that were normally ice-free, froze and snow fields remained at low altitudes throughout the year.
There is evidence the sun had similar periods of inactivity during the years 1100-1250 and 1460-1550. Sunspots generally follow a cycle of about 11 years, but cycles have varied from eight-15 years. The connection between solar activity and the earth’s climate is an area of ongoing and sometimes controversial research.
An approaching Grand Solar Minimum is gaining “support” including NASA with their recent SC25 prediction — though they stay clear of the implications. NASA’s forecast for the next solar cycle (25) reveals it will be the weakest of the last 200 years.The maximum of this next cycle — measured in terms of sunspot number, a standard measure of solar activity level — could be 30 to 50% lower than the most recent one. The agency’s results show that the next cycle started in 2020 and reach its maximum in 2025.
The new research was led by Irina Kitiashvili, a researcher with the Bay Area Environmental Research Institute at NASA’s Ames Research Center, in California’s Silicon Valley. It combined observations from two NASA space missions – the Solar and Heliospheric Observatory and the Solar Dynamics Observatory – with data collected since 1976 from the ground-based National Solar Observatory. One challenge for researchers working to predict the Sun’s activities is that scientists don’t yet completely understand the inner workings of our star. Plus, some factors that play out deep inside the Sun cannot be measured directly. They have to be estimated from measurements of related phenomena on the solar surface, like sunspots.
Time will tell whether the sun will once again go into another ‘Maunder Minimum’ within the lifetime of the present generation, but if this happens we’re likely to have a much colder climate for a few decades.