Solar Cycle 25 reached its maximum in October 2024
In 2019, the Solar Cycle Prediction Panel convened to gather and combine predictions for the still infant Solar Cycle 25.
SILSO
Solar Cycle 25 maximum
The Sun has been very active during the last few months. Since April 2024, many large and complex sunspot groups have adorned the solar disk driving the daily sunspot number regularly to well above 250 (see the SIDC/USET image for 7 August 2024 underneath).
Sunspots and aurora
Last weekend's polar lights have been witnessed by millions around the world. While many drove to dark places to watch this celestial spectacle, others grabbed a lawn chair and watched the baffling show from their own backyard. Children were woken up by their parents to watch the colours in the sky. The 10-11 May aurora certainly captured the attention and awe of the public and the media.
The Locarno station just completed a 5 year digitization project
The Locarno station just completed a 5 year digitization project archiving sunspot observations and data from 1 June 1957 onwards.
SILSO change of management
Due to a reshuffling of responsibilities, SILSO will from now on run under the single Directorship of Laure Lefèvre, and therefore any future questions related to the SILSO management or data should be addressed to Laure.Lefevre@oma.be. We take this opportunity to thank both Frédéric Clette and Laure Lefèvre for their dedication to the SILSO operations during many years.
New extended hemispheric sunspot numbers
On July 19, 2021, we added a new time series to our data products: extended hemispheric sunspot numbers starting in 1874. Those reconstructed numbers are based on the sunspot areas listed in the Greenwich photographic catalogue, and are calibrated on the SILSO reference hemispheric series, which starts only in 1992. This newly published series results from a collaboration between SILSO, the University of Graz (Austria) and the Skolkovo Institute of Science and Technology (Moscow, Russia).
Solar cycle minimum passed in December 2019
In January 2020, the 13-month smoothed sunspot number rose for the first time since the maximum of cycle 24 (April 2014). Most probably, this indicates that the minimum between cycles 24 and 25 was passed in December 2019.
New prediction method
Starting from a collaboration with the NCEI (NOAA, Boulder USA), we implemented new 12-month ahead predictions based on the McNish and Lincoln method. This rather simple method is based on a single mean cycle profile and is thus of "climatology" type. It was used as a standard for many years at NOAA, and we now add it to our other more advanced Standard Curves and Combined methods, allowing direct comparisons. Likewise, we now also provide a Kalman-filter optimized version of these new ML predictions.
New 'Spotless days' page
Regular solar observers have noticed that since mid-2016, the Sun has occasionally been devoid of sunspots. As the current solar cycle 24 will gradually give way to the new solar cycle 25, several consecutive days and even weeks without sunspots will become the norm. In order to have an idea on the number of spotless days, and how these numbers compare to past solar cycles, SILSO has created a “Spotless Days page”.
Transition to the new Sunspot Number successfully completed
Today marked a triple transition for us: - Uploading the new Sunspot Number archive files containing the daily, monthly and yearly re-calibrated sunspot numbers and the new Group Number series - In our Web site, switching to the new "Data" pages giving access to the new files, to updated graphics and also to the past version of the Sunspot Number - Adapting and running the entire monthly procedure to produce the provisional Sunspot Numbers for June 2015 and the associated 12-months forecast and EISN. Thus a lot of work in a single day for our small team.