World Data Center for the production, preservation and dissemination of the international sunspot number
The new solar activity cycle.
December 2019 confirmed as starting point of the new solar activity cycle
The reference date and amplitudes of the minima and maxima of the 11-year solar cycle are established on the base of the sunspot number maintained and distributed by the SILSO World Data center since 1981 at the Royal Observatory of Belgium.
The reference date and amplitudes of the minima and maxima of the 11-year solar... more