Solar Activity Stuck In a Rut

The sunspot cycle from 1995 to the present. The jagged curve plots actual sunspot counts. The solid smooth curve past the current date is the predicted solar activity. The current quiescence is occurring at a point forecasters thought the sun would be on an upswing of sunspot activity.

Scientists were fooled last fall when they thought an eerie calm between sunspot cycles had abruptly ended. The sun had been relatively free of sunspots since the last 11-year cycle ended earlier in the year.

A few dark patches that emerged on the sun’s surface in late November were thought to be the first spots of the new cycle.

But sunspots then became even more scarce, reaching the lowest number during the last year than at any time since 1913, nearly a century ago.

"We're experiencing a very deep solar minimum," says solar physicist Dean Pesnell of the Goddard Space Flight Center.

While deep solar calms were fairly common a hundred years ago, five of the most intense solar cycles on record have occurred in the last 50 years, according to sunspot expert David Hathaway of the Marshall Space Flight Center.

He says that the ones of 1901 and 1913 were longer than those the solar system is experiencing now.

Pesnell believes sunspot numbers will finally increase soon, “possibly by the end of the year,” to be followed by a solar maximum of below-average intensity in 2012 or 2013.

The deeper and longer solar minimum is probably a good thing for planet Earth. It means global warming will be marginally delayed, GPS navigation systems are more accurate and satellites stay in orbit longer.

But some meteorologists believe the low solar activity may also be the guiding force behind a bitter winter that shows no signs of finally ending across North America.

Graphic: David Hathaway - NASA/MSFC