Thursday, April 2, 2009

The Sun Is Giving Us The Silent Treatment

NASA data continues to indicate that the Sun’s current activity level, or lack-there-of, is the deepest solar minimum in a century. In fact, the Sun has not had a sunspot in 80 of the days so far in 2009. That’s 87% of the time this year, the Sun has been spotless. The Sun’s current spotless streak is 25 consecutive days, with the last sunspot observed in early March. The longest blank streak in the past century was 92 days, which occurred nearly 100 years ago during April, May, and June of 1913. While this solar minimum is notable (seriously, it hasn't been this quiet in nearly a century!), the Sun would have to remain blank from now until early June 2009 to tie the 1913 record. (For a check of the Sun’s daily solar activity, go to http://www.spaceweather.com/)


(Above: The sunspot cycle from 1995 to the present. The jagged curve traces actual sunspot counts. Smooth curves are fits to the data and one forecaster's predictions of future activity. Credit: David Hathaway, NASA/MSFC.)

The Sun has a regular cycle it goes through about every eleven years, with a predictable, steady rise and fall in solar activity (i.e., sunspots, irradiance, magnetic energy emission). And most NASA scientists thought 2008 was rock bottom for this solar cycle’s minimum. No sunspots occurred 73% of the days in 2008 (that’s 266 days out of 366). Only 1913 had more spotless days at 311 blank sun days.

But well into 2009, the Sun continues to give us the silent treatment, with an overwhelming majority of the days this year being blank. Year-to-date, the Sun has been “silent” 80 out of 92 days. Although the Sun continues to adhere to its traditional solar cycle, this minimum may be especially unusual because it is also accompanied by a 50-year low in solar wind pressure, a 12-year low in solar irradiance, and a 55-year low in solar radio emissions, according to NASA data. For more on those three points, check out NASA’s discussion here.

So if the Sun is in a minimum of activity, does this mean we don't need to worry about the sunscreen this Summer? NO! Slather on that good, protective sunscreen! Take it from someone who knows...a fair-skinned redhead with blue eyes. Yes, you guessed it, it takes me all of 10 minutes to turn from white to lobster red in the sun without protection. Wear sunscreen! Just do it. Seriously.
--Carrie