The Last Hoorah for Solar Cycle 23?
Magnetic activity on March 27th; white indicates N
magnetic poles, black S. Credit: ESA/SOHO/NASA.
A few blogs back I wrote about the 11-year cycle of ups and downs in solar activity–the Solar Cycle –and how over the last year or so the baton was supposedly passed from Cycle 23 to Cycle 24. But there has been an occurrence on the Sun that suggests we may be in somewhat of a gray zone….
For the past two or three years, the Sun has been downright boring. We set up our Sunspotter telescopes for visitors and try very hard to make what we see seem interesting–"See that perfectly blank circle of light? That’s the Sun! Really it is!"
About a week ago, the tedium was suddenly broken by a train of sunspots that rotated into view on Sun’s disk. Five–count'em– five sunspots! Finally, something to actually look at! And in the eyepiece of our Coronado Hydrogen-Alpha filter telescope there were filaments and plage! What are filaments and plage? Exactly! People wanted to know….
Then came the weird part: these were not Cycle 24 sunspots (I am not the Dread Pirate Roberts…); they were refugees from the supposedly defunct Cycle 23. While the distinction may be a fine point that doesn’t worry most of our visitors, it can still be a good talking point.
So, why were these five sunspots fingered as old solar trekkers rather than members of the next generation? It all comes back to what a solar cycle is–and sunspots, flares, prominences, and plage are merely details: manifestations of the Sun's magnetic convulsions. The Sun, like the Earth, generates an enveloping magnetic field–a big donut with a north and a south magnetic pole. On smaller scales there are plenty of twists and swirls and knots in the field caused by local "hot spots" of magnetic activity–which are what produce features like sunspots in the first place.
At solar maximum–the peak of activity of a solar cycle–the Sun's magnetic poles flip over, or reverse. In fact, it's this reversal that really lets us know when a solar maximum has arrived. (Earth's magnetic field also reverses polarity periodically–although this only happens every 200,000 years, on average.)
At the beginning of a solar cycle, new sunspot activity can be found at high solar latitudes, and as the cycle progresses, activity migrates toward the equator. On a finer nuance, the magnetic polarity of sunspots–which can be N or S, and are usually paired up, like the two ends of a bar magnet –are typically oriented east-to-west on the Sun's surface, one leading to the other as the Sun rotates. Which type of pole (N or S) leads and which trails depends on the overall magnetic "flip" state of the Sun's magnetic field.
To round out this report, the five surprise sunspots of yesterweek were lined up close to the Sun's equator, and the orientation of their magnetic poles bespoke their affiliation with the outgoing magnetic administration (Cycle 23). So far, only a single, high-latitude, reverse-polarity sunspot observed last January has signaled Cycle 24 .
Who knows? Maybe the magnetic candidates of Cycle 24 are still holding primaries, caucuses, and debates and have yet to begin some serious campaigning…
Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.
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Our family just returned from a camping trip in Yellowstone Park. We had not seen the park since the 1988 fires and we were expecting the worst. We were pleasantly surprised. The park has recovered quickly and the Yellowstone Fire Interpretive Center explains why. We recommend the park and the fire center highly. The fire center explained that 1988 was an extraordinary drought year and that, together with history making dry lightening, simply overwhelmed the park in fires. The fire center displays noted that these fires reoccur regularly every 250 to 400 years. It is interesting to research the 1988 Yellowstone fire and the factors leading up to it from a global warming perspective. Solar cycle 22 started just a couple of years before that summer of drought and dry lightening. Relative to other cycles, that solar cycle had 1) a very fast rise time – 2.8 years, 2) a very short cycle length – 9.7 years, 3) a high minimum sun spot number – 12.3, and 4) a high maximum sun spot number – 158.5. That solar cycle period can now be contrasted with the extended duration of solar cycle #23, to understand the increasingly cold winters we are experiencing. To help understand these natural forces at work, here is some additional information from by Richard Thompson. © Copyright IPS – Radio and Space Services.
Solar Cycle Number 22 (1986 – 1996) in Review
“Cycle 22 certainly provided us with many highlights. Early in the cycle the smoothed sunspot number (determined by the number of sunspots visible on the sun and used as the traditional measure of the cycle) climbed rapidly; in fact more rapidly than for any previously recorded cycle. This caused many to predict that it would eclipse Cycle 19 (peak sunspot number of 201) as the highest cycle on record. This was not to be as the sunspot number ceased climbing in early 1989 and reached a maximum in July of that year. Whilst not of record amplitude, Cycle 22 still rated as 4th of the recorded cycles and continued the run of recent large solar cycles (Cycles 18, 19 and 21 were all exceptional!). A very notable feature of Cycle 22 was that it had the shortest rise from minimum to maximum of any recorded cycle.
Sunspot Cycle Number Year of Minimum Minimum Sunspot Number Year of Maximum Maximum Sunspot Number Rise to Max (yrs) Fall to Min (yrs) Cycle Length (yrs)
14 1901.7 2.6 1907.0 64.2 5.3 6.6 11.9
15 1913.6 1.5 1917.6 105.4 4.0 6.0 10.0
16 1923.6 5.6 1928.4 78.1 4.8 5.4 10.2
17 1933.8 3.4 1937.4 119.2 3.6 6.8 10.4
18 1944.2 7.7 1947.5 151.8 3.3 6.8 10.1
19 1954.3 3.4 1957.9 201.3 3.6 7.0 10.6
20 1964.9 9.6 1968.9 110.6 4.0 7.6 11.6
21 1976.5 12.2 1979.9 164.5 3.4 6.9 10.3
22 1986.8 12.3 1989.6 158.5 2.8 6.8 9.7
23 1996.4 8.2 ? ?
The maximum phase brought some extraordinary intervals of activity. Prime amongst these was the March 1989 period which started on March 6th with the appearance of a large sunspot region on the eastern edge of the sun. The next 14 days produced 11 "X class" flares (the largest category in X-ray emission) and 48 "M class" (still very large flares). However, the most outstanding feature of the interval occurred on March 13-14 with one of the largest geomagnetic storms in the last 50 years. This storm had an amazing list of effects on earth and in space. Power systems in Canada and Sweden failed as large electric currents were induced in power lines and tripped protective relays. Increased atmospheric drag, resulting from the expansion of the earth's outer atmosphere during the disturbance, altered the orbits of many satellites with the result that NASA lost track of some of them for a short period. Satellite navigation systems failed to operate and High Frequency (HF) communication systems were also out of action. Aurorae were sighted at quite equatorial latitudes.
The maximum phase of the cycle appeared to end rather abruptly in early 1992 when monthly values of sunspot number dropped significantly. The decline of Cycle 22 to its minimum in May 1996 was also remarkable because of the lack of major flare activity. The cycle had a multiple personality – malevolent in its first half and quite benign in its decline. This behaviour contrasts with Cycle 21 which was more active in its decline than during its rise or even its maximum.
The cycle was less than 10 years in duration – a fair bit shorter than the "traditional" eleven year cycle. However, it is an interesting fact that all but one of the last seven cycles have been less than eleven years (Cycle 20 was the exception). We are in an era not only of large solar cycles but also short ones!
There is an old saying that there is "nothing new under the sun" – but this does not apply to the sun itself! Cycle 22 proved to be a remarkable cycle by any measure.” Google “Solar Cycle 23” to get a better understanding of the current changes we are experiencing in our climate. Google “Solar Inertial Motion” to get a better understanding of the long cycles of solar activity and their impact on earth’s climate.