Kenneth Tapping, a solar researcher and project director for Canada's National Research Council, is among those looking at the sun for evidence of an increase in sunspot activity.

Solar activity fluctuates in an 11-year cycle. But so far in this cycle, the sun has been disturbingly quiet. The lack of increased activity could signal the beginning of what is known as a Maunder Minimum, an event which occurs every couple of centuries and can last as long as a century.

Such an event occurred in the 17th century. The observation of sunspots showed extraordinarily low levels of magnetism on the sun, with little or no 11-year cycle.

This solar hibernation corresponded with a period of bitter cold that began around 1650 and lasted, with intermittent spikes of warming, until 1715. Frigid winters and cold summers during that period led to massive crop failures, famine and death in Northern Europe.