The Big Wobble: ARE SUNSPOTS DISAPPEARING?

Saturday, 22 August 2009

ARE SUNSPOTS DISAPPEARING?

QUIET SUN: According to NOAA sunspot counts, the longest stretch of spotless suns during the current solar minimum was 52 days in July, August and Sept. of 2008. The current spate of blank suns is putting that record in jeopardy. The sun is entering its 43rd consecutive day with no sunspots, and there are none in the offing. Deep solar minimum continues.

ARE SUNSPOTS DISAPPEARING? Sunspots are made of magnetism. The "firmament" of a sunspot is not matter but rather a strong magnetic field that appears dark because it blocks the upflow of heat from the sun's fiery depths. Without magnetism, there would be no sunspots.

That's what makes the following graph a little troubling:

According to Bill Livingston and Matt Penn of the National Solar Observatory in Tucson, Arizona, sunspot magnetic fields are waning. The two respected solar astronomers have been measuring solar magnetism since 1992. Their technique is based on Zeeman splitting of infrared spectral lines emitted by iron atoms in the vicinity of sunspots. Extrapolating their data into the future suggests that sunspots could completely disappear within decades. That would be a bummer for Spaceweather.com.

Don't count out sunspots just yet, however. While the data of Livingston and Penn are widely thought to be correct, far-reaching extrapolations may be premature. This type of measurement is relatively new, and the data reaches back less than 17 years. "Whether this is an omen of long-term sunspot decline, analogous to the Maunder Minimum, remains to be seen," they caution in a recent EOS article.