Many people that have have an interest in the interaction between the Sun and Earth have been keeping a watchful eye on several metrics of solar activity recently. The most popular of course has been sunspot watching.
The sun has been particularly quiet in the last several months, so quiet in fact that Australia’s space weather agency recently revised their solar cycle 24 forecast, pushing the expected date for a ramping up of cycle 24 sunspots into the future by six months.
On August 31st, at 23:59 UTC, just a little over 24 hours from now, we are very likely to make a bit of history. It looks like we will have gone an entire calendar month without a sunspot. According to data from NOAA’s National Geophysical Data Center, the last time that happened was in June of 1913. May of 1913 was also spotless.
With the current space weather activity level of the Sun being near zero, and the SOHO holographic imaging of the far side of the sun showing no developing spots that would come around the edge in the next 24 hours, it seems a safe bet to conclude that August 2008 will be the first spotless month since June 1913.
Here is the sun today, at 09:14UTC August 30th:
Click for a very large image
Some people who watch the sun regularly might argue that August wasn’t really spotless, because on August 21st, a very tiny plage area looked like it was going to become a countable sunspot. Here is an amateur astronomer’s photo of the event:
August 21st, 2008 spots – Photo: Pavol Rapavy
But according to solar physicist Leif Svalgaard, who regularly frequents this blog:
According to NOAA it was not assigned a number on Aug.21st nor on Aug.22.
So without an official recognition or a number assigned, it should not be counted in August as actual sunspot.
It has also been over a month since a countable sunspot has been observed, the last one being on July 18th. Since then, activity has been flat. Below is a graph of several solar metrics from the amateur radio propagation website dxlc.com for the past two months:
Click image for original source
They have a table of metrics that include sunspots, and their data also points to a spotless August 2008. See it here: http://www.dxlc.com/solar/indices.html
So unless something dramatic happens on the sun in the next 24 hours, it seems a safe bet that August 2008 will be a spotless month.
Update: As commenter Jim Powell points out,
There was a stretch of 42 spotless days from 9/13/1996 to 10/24/1996. Today we have equaled this period. Check out Jan Janssens spotless days page http://users.telenet.be/j.janssens/Spotless/Spotless.html.