As you can see, the Sun is keeping quiet, devoid of sunspots. As the world awaits an increase in solar activity to celebrate the onset of a new solar cycle, our closest star keeps a blank face and keeps us guessing. This most recent image was taken today by the Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI) instrument. MDI measures plasma velocity and magnetic field strength at the top of the convection zone, so it is an invaluable sunspot detector. Sunspots are a good indicator about how active the Sun is, as when the magnetic field becomes stressed and twisted, it is forced from the convection zone, through the photosphere, chromosphere and high into the corona. These protrusions then fill with plasma and glow as coronal loops. The more magnetic activity there is, more sunspots appear. But, it would seem, the Sun remains magnetically inactive seven months since the beginning of Solar Cycle 24…
There has been much debate about what this quiet period means for the Sun. Well, it might be having an extended sleep, but solar minimum is a natural period of time in the 11-year solar cycle. Some theories say that within the next few months, we’ll notice a massive increase in sunspot population, heralding a very violent solar maximum by 2011. Others are more cautious and say there will be nothing out of the ordinary during the next 11 years. At the other end of the spectrum, we have the theory that we are facing a debilitating lull in solar activity, possibly reducing solar heating on the Earth, plunging us into a mini-ice age. Personally, I reckon we’ll see more normal solar activity soon, possibly more, possibly less active than the last cycle, but certainly no extremes.
However, this is a superb time to compare the current Sun with a more active version six years ago. In the image (left), the contrast between solar maximum and solar minimum couldn’t be greater. On the left, the Sun has a highly dynamic surface, coronal loops and bright patches indicating rapid plasma heating. On the right is the Sun we see today, some minor activity but nothing to report home about. These images were taken again by SOHO, but looking through a different filter (and therefore different wavelength) with the Extreme ultraviolet Imaging Telescope (EIT). The false colour green means we are looking at a wavelength of 195A, which is plasma radiating at approximately 1 million Kelvin. The first thing that becomes obvious with the right-hand image is the lack of 1 million K plasma. Therefore there is little heating energy input to the coronal plasma from the solar interior. Weak plasma heating = low magnetic activity (as coronal heating mechanisms are dominated by magnetic energy). Boring really.
However, over at Space Weather Alan Friedman caught this spectacular image (above) of prominences hanging above the limb of the Sun. These eerie strands of cool plasma (as seen in the Hα line) are supported by a complex of tenuous magnetic fieldlines projecting a few hundred thousand kilometres into the lower corona that would otherwise be difficult to see if the Sun were more active.
astroengine.com 
Dear God, Ian! Next you’re going to be telling me that solar output isn’t responsible for global climate change; bollocks, I say!
Nice article.
Ethan
The calm before the “storm” ?
*Twiddles his thumbs…*
*Whistles a tune…*
*Watches the grass grow…*
So, when’s this next cycle supposed to get interesting again? =o]
As an aside, I’m wondering whether NASA’s “solar conveyor belt” model is incorrect?
(Diagram of the Major Plasma Flows Inside the Sun)
http://www.nasa.gov/centers/goddard/news/topstory/2006/solar_cycle_flow.html
Notice figure H… See anything wrong? It’s subtle! Think lower right quadrant. Is it just me or are the arrows pointing in opposite directions?
(Inconsistency highlighted.)
http://picasaweb.google.com/mgmirkin/Physics/photo#5218318349764201842
Seems NASA’s model is internally inconsistent. Or am I mistaken?
Then, see Alfven’s Solar Circuit diagram.
(Alfven’s solar circuit)
http://picasaweb.google.com/mgmirkin/Physics/photo#5152327471592420642
Primary currents come in at the poles like a big Faraday motor, and exit along the plane of the equator. Secondary currents are induced while the primary currents are rising or falling. At local maxima / minima, the secondary currents likely disappear, then reverse with the slope of the line tangent ot the sinusoidal variation of the input current. Which may also account for the flip in signs of the sunspots over one FULL 22 year cycle (if we’re getting back to both the same point in the cycle AND the same polarity of the sunspots).
I tend to favor Alfvén’s model. Right now, we seem to be at one of the local minima / maxima, where the tangent line to the sinusoidal main current is basically zero.
One possible explanation, anyway…
Regards,
~Michael
Err, that should have read:
“Right now, we seem to be at one of the local minima / maxima, where the >>slope of the<< tangent line to the sinusoidal main current is basically zero.”
IE, no change (rising or falling current), thus no induced secondary current.
My bad.
~Michael
Thanks Michael for the insight! Will be checking out those links ASAP!
Hope you are doing well, Ian 🙂
I have not much time, but I've got many useful things here, love it!
I have not much time, but I've got many useful things here, love it!
I GET THE IMPRESSION THAT MOST PEOPLE THINK WE HUMANS ARE IMMUNE TO ANY CHANGE ON OUR PLANET FROM OUTSIDE INTERFEANCE WEVE HAD IT GOOD FOR SO LONG HERE ON EARTH THAT PEOPLE THINK OUR EARTH WILL JUST CARRY ON THE SAME AS ITS BEEN DOING FOREVER STOP RIGHT THERE ARE WE ABOUT TO SEE WHAT REALLY HARD TIMES ON EARTH CAN BE LIKE THE ANSWER IS YES CLIMATE CHANGE WEATHER PATTERNS ARE CHANGING THE JET STREAMS USUAL DIRECTION IS CHANGING RAIN PATTERNS ARE CHANGING MORE FLOODS MORE DROUGHTS THE ANTARTIC ICE SHELF IS GROWING EUROPE IS GETTING COLDER WINTERS BLOWING IN FROM SIBERIA PAKISTAN HUGE FLOODS RUSSIA DROUGHTS OCEAN CURRENTS LIKE THE GULF STREAM ARE WEAKENING BY BECOMING LESS SALTY ATMOSPHERIC CHANGES HAVE BEEN SEEN AS WELL THIS IS DEFFINETLY CLIMATE CHANGE 100PER CENT BUT WHICH WAY WARMER OR COLDER MY BELIEF IS WITH THE LATTER STUDYS IN THE GREENLAND ICE SHEETS SHOW THAT EVERY TIME EARTH WENT INTO A COLDER PERIOD THE WORLD ALWAYS WARMED UP FIRST FOR AROUND 25YEARS OR SO THEN TEMPS WOULD START TO FALL QUICKLY WITHIN AROUND 10YEARS OR SO TILL EARTH GOT COLD ENOUGH TO BE SEEN AS A LITTLE ICE AGE OR A FULL ON ICEAGE SOME WOULD LAST ONLY 1000 YEARS OR SO BUT COLD ENOUGH TO MAKE OUR LIFES TODAY VERY HARD TO SURVIVE