Solar activity can be easily monitored by the number of sun spots. Regular recordings of the phenomenon have been available since the middle of the 18th century, with the star’s activity reaching peaks about every 11 years. The current Solar Cycle 24, is about to pass its prime in a matter of months, according to observations.
Matthew Penn of the National Solar Observatory says the strength of magnetic field in sunspots in waning, and the sunspot cycle may disappear altogether. “If this trend continues, there will be almost no spots in Cycle 25, and we might be going into another Maunder Minimum,” he said.
Maunder Minimum is a period between about 1645 and 1715, in which sunspots became extremely rare. In fact some 18th century astronomers believed sunspots to be a myth. The period coincides with the so-called Little Ice Age, a time when the climate became cold enough for the River Thames in London to freeze in winter.