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Sunspot activity is at a low point in 2009.
We know that sunspot counts generally rise and fall every 11 years on the average. We also know that their magnetic fields reverse themselves every 22 years.
The year 2008, however, earned what NASA designated as the Sun’s “blankest year” of the space age; on 266 of the year's 366 days, there were no sunspots. It hasn't been this quiet since the year of 1913.
Sunspot counts for 2009 have been very low, too. "We're experiencing a very deep solar minimum," says solar physicist Dean Pesnell of the Goddard Space Flight Center.
This all begs the question: does solar activity have a long-term effect here on Earth?
- It seems that times of depressed solar activity correspond with times of global cold. For example, during the 70-year period from 1645 to 1715, few if any sunspots were seen even during expected sunspot maximums, and Western Europe entered a virtual deep-freeze known as the Little Ice Age.
- Conversely, times of increased solar activity have corresponded with global warning. During the 12th and 13th centuries the Sun was active, and the European climate was quite mild.
In 2008, the Sun set some new records:
- A 50-year low in solar wind pressure: Decreased solar winds allow more galactic cosmic rays into the inner solar system. This poses health risk for astronauts. Another effect is fewer aurorae, or northern lights, on Earth.
- A 12-year low in solar "irradiance": The sun's diminished brightness has already lead to a dramatic decrease in extreme UV wavelengths. This means that Earth's upper atmosphere is less heated by the Sun, which may lead to a slight global cooling. Another effect is that satellites operate longer due to less atmospheric drag. Space junk, however, stays in orbit longer (a risk to satellites).
- A 55-year low in solar radio emissions: Some researchers believe that the lessening of radio emissions is an indication of weakness in the sun's global magnetic field.
Of course, there have been quiet periods for our Sun in the past. Over a hundred years ago, we had a solar minimum that lasted as long as the current one (although one more year of inactivity will surpass last century's minimum).
In May, 2009, an international panel of experts predicts that the current solar cycle will peak in 2013 with a below-average number of sunspots. The Sun should remain calm for at least another year.
In late October, 2009, the Sun did show a rare burst of activity. Sunspot "1029" unleashed multiple solar flares. Will the Sun come back to life? It appears that Sunspot "1029" is a member of the new Solar Cycle 24. Stay tuned to see what happens with our surprising Sun . . .
