From NASA News: Are Sunspots Disappearing?
September 3, 2009: The sun is in the pits of the deepest solar minimum in nearly a century. Weeks and sometimes whole months go by without even a single tiny sunspot. The quiet has dragged out for more than two years, prompting some observers to wonder, are sunspots disappearing?
“Personally, I’m betting that sunspots are coming back,” says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, “there is some evidence that they won’t.”
Penn’s colleague Bill Livingston of the NSO has been measuring the magnetic fields of sunspots for the past 17 years, and he has found a remarkable trend. Sunspot magnetism is on the decline:
Above: Sunspot magnetic fields measured by Livingston and Penn from 1992 – Feb. 2009 using an infrared Zeeman splitting technique. [more]
“Sunspot magnetic fields are dropping by about 50 gauss per year,” says Penn. “If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015.”
This disappearing act is possible because 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 interior. If Earth lost its magnetic field, the solid planet would remain intact, but if a sunspot loses its magnetism, it ceases to exist.
“According to our measurements, sunspots seem to form only if the magnetic field is stronger than about 1500 gauss,” says Livingston. “If the current trend continues, we’ll hit that threshold in the near future, and solar magnetic fields would become too weak to form sunspots.””This work has caused a sensation in the field of solar physics,” comments NASA sunspot expert David Hathaway, who is not directly involved in the research. “It’s controversial stuff.”
The controversy is not about the data. “We know Livingston and Penn are excellent observers,” says Hathaway. “The trend that they have discovered appears to be real.” The part colleagues have trouble believing is the extrapolation. Hathaway notes that most of their data were taken after the maximum of Solar Cycle 23 (2000-2002) when sunspot activity naturally began to decline. “The drop in magnetic fields could be a normal aspect of the solar cycle and not a sign that sunspots are permanently vanishing.”
Penn himself wonders about these points. “Our technique is relatively new and the data stretches back in time only 17 years. We could be observing a temporary downturn that will reverse itself.”
The technique they’re using was pioneered by Livingston at the NASA-supported McMath-Pierce solar telescope near Tucson. He looks at a spectral line emitted by iron atoms in the sun’s atmosphere. Sunspot magnetic fields cause the line to split in two—an effect called “Zeeman splitting” after Dutch physicist Pieter Zeeman who discovered the phenomenon in the 19th century. The size of the split reveals the intensity of the magnetism.
Right: Zeeman splitting of spectral lines from a strongly-magnetized sunspot. [more]
Astronomers have been measuring sunspot magnetic fields in this general way for nearly a century, but Livingston added a twist. While most researchers measure the splitting of spectral lines in the visible part of the sun’s spectrum, Livingston decided to try an infra-red spectral line. Infrared lines are much more sensitive to the Zeeman effect and provide more accurate answers. Also, he dedicated himself to measuring a large number of sunspots—more than 900 between 1998 and 2005 alone. The combination of accuracy and numbers revealed the downturn.
If sunspots do go away, it wouldn’t be the first time. In the 17th century, the sun plunged into a 70-year period of spotlessness known as the Maunder Minimum that still baffles scientists. The sunspot drought began in 1645 and lasted until 1715; during that time, some of the best astronomers in history (e.g., Cassini) monitored the sun and failed to count more than a few dozen sunspots per year, compared to the usual thousands.
“Whether [the current downturn] is an omen of long-term sunspot decline, analogous to the Maunder Minimum, remains to be seen,” Livingston and Penn caution in a recent issue of EOS. “Other indications of solar activity suggest that sunspots must return in earnest within the next year.”
Whatever happens, notes Hathaway, “the sun is behaving in an interesting way and I believe we’re about to learn something new.”
h/t to Michael Ronayne
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>> NoAstronomer (07:43:35) :
The sun is not, currently, hot or dense enough to fuse anything other than hydrogen. <<
I seem to remember that the primary division between brown dwarfs and low mass stars was the presence of lithium. Lithium fuses at a temperature slightly below that required to fuse hydrogen, so most main sequence stars (including the Sun) are lithium poor.
The presence of lithium in older stars requires explanation. The usual one is that it has probably gobbled up a brown dwarf.
Jim
Robinson (05:39:30) :
I didn’t happen at the last minimum. Unfortunately, the data span is only 17 years, so no one knows what the longer history is or what the future may hold.
Mark Fawcett (07:10:28) :
I don’t think you understand, did you read the papers?
This is brand new science. Livingston and Penn are the first to report this phenomemon and are quick to say they don’t know how things will turn out.
The trend appears to be a straight line, so that what they fit it to. What would you have used?
They did not project the field strength to zero, but to 1500 gauss, down from about 3000. At that point the contrast between sunspot umbra and the rest of the solar disk will be so low that the sopts will appear invisible.
Please, go bang your head – several of rest of us who have been following this find this to be the most fascinating thing we have read in this blog, some to the point of checking with Leif after each sunspeck with “Did Livingston measure it?” “Is it still on the trend line?” I’m more patient than that, perhaps if you read both of the papers you would understand that you could learn a little patience yourself.
Dear Colleagues… Science Express published this news yesterday:
http://www.sciencemag.org/cgi/rapidpdf/1178868v1.pdf
It refers to the observation of magnetic monopoles and Dirac strings in magnetic spin ice Dy2Ti2O7 (Dysprosium Titanate). If the observation is confirmed, it will constitute an important verification on the inflationary theory and subsequent deterioration of the Big Bang theory.
On the other hand, the observation of magnetic monopoles, if it is systematically confirmed, will be useful for explaining quantum tunneling in observed solar phenomena besides the normal explanations like transverse anisotrpy, transverse magnetic field, fluctuations of the energy of the potential barrier, etc., including the “bangs” reported where solar magnetic lines reconnect.
I hope there will be many particle physicists who reproduce the experiment and confirm the observations of magnetic monopoles by Morris et al.
🙂
Carsten Arnholm, Norway (07:33:14) :
“You never get up early enough to see the red Aurora over the mountain top”
So, Dass did mention the aurora after all. And sleet, too. And your translation is fine.
Dear Dr. Svalgaard,
I will check with my uncle at the University of Tromsø about Petter Dass and rain. He knows many people at Nordlysobservatoriet. At this page you can see the typical information we learn in Norway about Nordlys. This link is for Dr. Svalgaard:
http://www.museumsnett.no/ntm/no/utstillingene/nordlys/nnordlys.htm
The rest of the world can try Google Translator:
http://translate.google.co.uk/translate?hl=en&sl=no&u=http://www.museumsnett.no/ntm/no/utstillingene/nordlys/nnordlys.htm&ei=XkWhSoVTjIWwBqnDudIE&sa=X&oi=translate&resnum=1&ct=result&prev=/search%3Fq%3Dnordlys%2Bsite:.museumsnett.no%26hl%3Den%26sa%3DG
NORDLYSET KOMMER OG GÅR
Nordlyset varierer i takt med forholdene på solen. Mens solflekkene kommer og går i perioder på om lag 11 år, følger nordlysene med i samme takt, bare et par år forsinket. I lange perioder har solflekkaktiviteten vært meget lav og antall observerte nordlys vært tilsvarende få. Dikteren og presten Petter Dass (1645-1701) levde i en av disse periodene, Maunder- minimum, og så ikke nordlys.
Den geografiske beliggenheten av nordlyset, nordlyssonen, er bestemt av jordens magnetfelt som dreier omkring som tiden går. Da Kongespeilet ble skrevet omkring år 1250, var nordlyssonen trolig langt nord for de sentrale deler av Norge, og vikingene opplevde nordlyset bare på sine ferder til Grønland.
Leif Svalgaard (07:35:57) :
coaldust (00:33:36) :
The Penn quote indicates that the magnetic field strength is decreasing. I call that “going away”? Perhaps you mean that the magnetic field decreased below that required for a spot to form, but didn’t completely go away? Could you clarify please? Thanks in advance.
There is a difference between field and flux. The flux is field strength times area, and is what counts. Sunspots are concentrations of flux, i.e small areas with high field strength formed by the coalescence of yet smaller flux elements. When the field strength is 1500 Gauss or above, it is strong enough to hinder the convection that brings heat up from below and the spot looks darker than the surroundings. So the ‘darkness’ of a spot depends on how much the field is stronger than 1500 Gauss. Imagine we have 10 spots with field strength 1400 Gauss and one spot with field strength 2000 Gauss, then the total flux [assuming all spots have the same area, A] for the first ten [and invisible spots] is 1400*10*A, and for the lone, but visible, spot 2000*1*A, or seven times less. So all it takes to have a Maunder Minimum is for the field strength to fall just below 1500 Gauss [and not go to zero]. Then there can be lots of flux [as required for the cosmic ray modulation], but no visible spots. We don’t know if this is what actually happened, but it is a viable explanation.
Please make corrections where appropriate, Lief, but while I accept your explanation, it seems to me not entirely the pertinent point. The magnetic field which modulates cosmic rays out at the distance of the Earth is actually a low order moment field; while the field in a sunspot is much higher order and will decay very quickly with distance from the sun. Thus, it is not at all surprising that the magnetic field of the sun could remain almost constant at Earth distance, but sun spots vanish entirely.
Heat is conveyed from the Sun’s interior via a combination of radiation and convection. Convection in turn can tangle magnetic field lines and concentrate them to a very significant degree. Concentrated magnetic fields lead to an increase in viscosity of the fluid material making up the Sun and should decrease the vigor of convection. Magnetic field lines can diffuse through the solar material, and this diffusion then allows the dissipation of sun spots and lowers viscosity again, at a rate which depends on electrical conductivity. Electrical conductivity in turn increases with material temperature. Thus we have a complicated feedback system of convection upon itself mediated through magnetic field. My understanding is that this feedback is the basis of the sun spot cycle in the first place. Am I correct?
What seems interesting to me is that despite the changes in convection implied by sunspots, the TSI is relatively constant–suggesting that radiation can make up for decreasing convection locally.
By the way, I have never used the unit Gauss, having not used the cgs system, so I have trouble visualizing what we are speaking about. The SI unit is the Tesla, and 1500 Gauss is 0.15T. The normal magnetic field of the Earth is about 0.00006T. A really big laboratory field strength is 1T or so.
“”” Leif Svalgaard (23:57:05) :
Invariant (23:04:06) :
Are there historical evidence that the aurora did exist during the Maunder minimum?
Yes, http://www.leif.org/EOS/1990MNRAS247.pdf “””
I would think Leif, that the Earth’s own magnetic field, plus any bursts of charged particles from the sun, is a sufficient condition to get some auroral displays. Cosmic rays would seem to be too sparse to generate aurorae.
My understanding of the Maunder Minimum (from “Wille” Wei-Hock Soon) is that although sunspots disappeared, the 11/22 year solar cycles did not; so presumably they manifest themselves other than by sunspots.
But I could be wrong on that.
George
NoAstronomer wrote:
“…The sun is not, currently, hot or dense enough to fuse anything other than hydrogen….”
Then whence cometh the sun’s iron atoms that are observed in this study?
“…The technique they’re using was pioneered by Livingston at the NASA-supported McMath-Pierce solar telescope near Tucson. He looks at a spectral line emitted by iron atoms in the sun’s atmosphere. Sunspot magnetic fields cause the line to split in two—an effect called “Zeeman splitting” after Dutch physicist Pieter Zeeman who discovered the phenomenon in the 19th century. The size of the split reveals the intensity of the magnetism…”
>i>John Peter (00:42:08) :
If I remember correctly the whole idea of Dr Svensmark’s cloud theory was that the Sun’s magnetic field held cosmic rays in check and if the Sun’s magnetic field weakened increased cosmic ray bombardment of Earth would lead to greater global cloud cover and cooling. If the weakening of the magnetic field continues it follows that cooling will occur potentially leading to a DM or MM???
That is their theory.
Steve Keohane (08:42:46) :
Bob Shapiro (20:40:19) I have a problem with Tmin/Tmax averaging though. For example, if on March 10th Tmin=40°F and Tmax=80°F, and again on June 10th Tmin=40° and Tmax=80°F, they will have the same average, but do not represent the same amount of heat. By June we are looking at more hours of day, read warm, and fewer hours of night, read cool. An hourly reading on each of these two days, averaged for each day would show this, (Tmin/Tmax)/2 does not.
Interesting. Does the “seasonally adjusted” postscript take this into account?
Two images via spaceweather.com
First 4th Jan 2008 (980)
http://www.spaceweather.com/images2008/04jan08/midi512_blank_b.gif?PHPSESSID=3hkp3e6c1qe18gns74drlkvuj3
Second 1st Sept 2009 (1025)
http://www.spaceweather.com/images2009/01sep09/midi512_blank.gif?PHPSESSID=rdulii36nav0fcs8p62m8vn3l6
The later spot is much closer to the equator. Is it possible that solar cycle 24 is progressing normally but with very few sunspots????
>> noaaprogrammer (10:34:28) :
Then whence cometh the sun’s iron atoms that are observed in this study? <<
Probably from numerous supernovae that preceded the formation of the Solar System. The Sun is not a first generation star. The interstellar medium is constantly being seeded with ashes from supernova explosions and planetary nebulae from dying red giants too light to go supernova. Indeed, a nearby supernova may have triggered the formation of our solar system.
Jim
“Scientists familiar with the work, to be published Friday in the journal Science, said it provided fresh evidence that human activity is not only warming the globe, particularly the Arctic, but could also even fend off what had been presumed to be an inevitable descent into a new ice age over the next few dozen millenniums.”
I said the same exact thing as the bold remark in a comment in Frank Lansner’s article where he put together dozens of proxies. In his study the MWP was warmer than present and since his study used so many proxies I’d tend to believe him more than just looking at the Arctic.
We all should keep in mind that the greenhouse effect could be masked by a cooling trend. Many estimates say we could get as much as 1.5C warming/century and we haven’t been seeing it. If it was masking a cooling trend then positive feedbacks would be negated as well.
Best time for daily minimum is shortly after sunrise (for a typical day in the mid latitudes about 8:00 am if the sky is clear). The daily minimum is driven by a balance between radiant heat loss to the cold sky and heat gain from the direct heating of the sun. When the sun is just above the horizon, it is still losing out in the battle to radiant heat lost to the sky (if cloudless).
Instead of a clock time, the best way to do it would be by referencing the measurement to the time of local sunrise, and local noon. That should work out to an hour or so after local sunrise in the winter for T-min, much sooner in summer when the sun rises sooner and faster (height above horizon varies more rapidly in summer).
My experience on T max is about 2:00-4:00 pm ( 40 deg N. long) depending on cloud conditions. If the sky is clear and cloudless temperatures will peak later in the day. If like much of mid-America, clouds build in the afternoon, that can shut off heating around 2:00 pm.
I have seen studies on this issue by folks researching Solar flat plate thermal collectors, and solar pond systems. They need to consider both.
(radiant cooling to the sky can freeze water in desert environments even if air temps never drop below 50 deg F. at night)
Larry
From some previous large star that puked out iron as it died into the interstellar gas clouds the sun collected its gas from as it formed.
Iron formation only occurs very late in a stars life cycle.
Super nova’s have spread heavy elements through out the galaxy over the last few billion years, so all stars (and rocky planets) contain heavier elements manufactured during those old stars life cycles.
Larry
Nasa seems to take one step forward and two back. NASA’s newest press release on solar activity offers a fairer view of the uncertainty surrounding the sun, however on the same day Tom Wagner of NASA went on CNN to mislead the public about the state of Earth’s ice:
http://www.cnn.com/video/#/video/tech/2009/09/03/nasa.coolest.earth.video.cnn?iref=videosearch
Tom disingenuously highlights that an iceberg broke off Ross Ice Shelf a few years ago and that the Larson Ice Shelf “collapsed catastrophically”, insinuating that Antarctica is falling apart, when in reality Antarctic Sea Ice Extent is currently above the historical average:
http://nsidc.org/data/seaice_index/images/daily_images/S_timeseries.png
Invariant (09:51:36) :
I will check with my uncle at the University of Tromsø about Petter Dass and rain.
According to http://www.leif.org/EOS/1990MNRAS247.pdf there were 118 aurorae observed in Central Europe during the MM.
I have often wondered about Norway and Iceland where aurorae now are common, that if they disappeared during the MM, people would have noticed that and commented upon it as strange. The lack of any such comment may be taken as evidence, perhaps, that the aurorae did not disappear. The only real evidence we have of the solar magnetic field still being near ‘normal’ is that the modulation of cosmic rays was not noticeably weaker during the MM.
noaaprogrammer (10:34:28) :
From the stars upon whose ashes our solar system is built. I.e. the same place the Earth’s iron core, uranium deposits, etc. came from. I’m not just a
descendent of apes’ ancestors, I came from a supernova!
I didn’t see this in the post above…was there a hardware change ~2002/2003? Why is is pre-2003(ish) missing all of the high-frequency contend of the post-2003(ish) era?
edt (11:30:59) :
I didn’t see this in the post above…was there a hardware change ~2002/2003? Why is is pre-2003(ish) missing all of the high-frequency contend of the post-2003(ish) era?
Because Livingston didn’t begin a regular, intensive observing campaign before 2003. On this plot you can see a cross for every single observation: http://www.leif.org/research/Livingston%20and%20Penn.png
DaveE (17:55:40) :
REPLY – It must do. Tmax is almost always during the day and Tmin is almost always at night for any given location. ~ Evan]
I note you cover your ass with almost always.
I think it was more a recognition of fact than a CYA. There are times that a cold pool of air sitting in a low valley gets blown out by descending (heating) winds, for example. I lived for a couple of decades in a valley where the winter fog sometimes would sit for days. WHENEVER it finally cleared off was the first time the temperature would significantly move (one way or the other).
BTW. What’s the best time to record max/min for a given day? (For an experiment, let you know after I’ve finished.)
When it happens.
You need a “recording thermometer” that is running for the whole 24 hours. They you read the three indicators: MIN MAX and Current.
Jim Masterson (10:51:31) :
>> noaaprogrammer (10:34:28) :
Then whence cometh the sun’s iron atoms that are observed in this study? <Probably from numerous supernovae that preceded the formation of the Solar System. The Sun is not a first generation star. The interstellar medium is constantly being seeded with ashes from supernova explosions and planetary nebulae from dying red giants too light to go supernova. Indeed, a nearby supernova may have triggered the formation of our solar system.<
Is there a spectrographic database that is keeping track of the elemental make-up of the sun over time? I know that any percent change among its elements might be too small to detect even over millenia, but that shouldn't preclude us from starting now.
The article says “Sunspot magnetic fields are dropping by about 50 gauss per year,” says Penn. “If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015.”
According to the graph, by 2015, mag fields will be only 1800 gauss. Is that the point at which sunspots vanish? I think someone drew a conclusion from the chart without realizing that the y axis ranged from 1800 to 3200 gauss.
Nonetheless, I too am quite convinced there is a strong relationship between variations in solar activity and earth’s climate. There is much stronger evidence and compelling arguments than the econuts spew with their CO2 hysteria. Sheeesh!
noaaprogrammer (12:19:05) :
Is there a spectrographic database that is keeping track of the elemental make-up of the sun over time? I know that any percent change among its elements might be too small to detect even over millenia, but that shouldn’t preclude us from starting now.
The changes are too small to see over the limited time humans have existed, but the elemental make-up of the Sun is known [some elements better than others] as well of that of many stars.
savethesharks (06:17:22) :
Our leaders are too busy being informed by those who are fascinated by what would happen if the Earth turned into another Venus theory.
They really should be concerned with what is presently happening on the Earth and the Sun.
Or, to be more specific: What isn’t happening on the Earth and the Sun.
Leif Svalgaard (11:25:59) :The lack of any such comment may be taken as evidence, perhaps, that the Aurorae did not disappear.
Thanks a lot for the interesting discussion and in particular this excellent paper which I enjoyed reading: http://www.leif.org/EOS/1990MNRAS247.pdf.
Now, I am mostly curious and clearly a beginner in studying sun cycles (possibly you could write another book, should sell very well in these interesting times), but since the amplitude and frequency of the Aurora is in tune with the sun cycles, is there any scientific evidence that the Aurora is weaker during periods with little sunspots, for example during cycle 14 and 15 in the beginning of the previous century?
http://www.windmedia.net/auror.htm
If the Aurora is weaker in the absence of sunspots is likely that it was even weaker during Maunder Minimum?