Amateur telescope photographer Thierry Legault has gained renown in recent years taking photographs of spacecraft in orbit… from the ground, with them either reflecting sunlight as they cross the terminator, or silhouetted by the moon, or in recent days, silhouetted by a near spotless sun.
His most recent accomplishment is this solar silhouette of the International Space Station docked with Space Shuttle Atlantis on its STS-132 mission. While many have marvelled at his accomplishment, we’ve heard less about the continuing near-spotless state of the sun in his photograph. This one sunspot region counted enough on May 22nd to make the daily sunspot count be 15!
It appears that the sunspot and 10.7 progression for Solar Cycle 24 have hit a bit of a roadblock in recent months, according to NOAA’s Solar Cycle Progression and Prediction Center.
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Solar wind velocity still up in the 500/600kps region;
http://www.spaceweather.com/
hot hot hot!
Ralph, what about Anna V’s explanation :
“Once we get into gasses and plasma, or even fluids, the void will be filled eventually by diffusion with molecules coming from the maxwellian distribution of momenta and energies of the molecules in the thick ring shell above, which for the sun, are at high temperatures. “
If the net gravitational force at the center is close to null then the hot/kinetically energetic particles at the border of the void will cross that border without difficulty, and begin filling the void by diffusion, even though there’s no gravitation pull towards the center. (Just repeating part of what Anna said, I think).
Leif Svalgaard says:
June 30, 2010 at 3:02 am (Edit)
tallbloke says:
June 29, 2010 at 9:52 pm
If the Corona is not affected, how are we able to see sunspots through the corona?
Because the corona is so tenuous [optically thin] at visible wavelength. At radio wavelengths the corona is not transparent.
Are there any data on coronal holes coinciding with sunspot locations?
Ulric Lyons says:
June 30, 2010 at 5:35 am (Edit)
Solar wind velocity still up in the 500/600kps region;
http://www.spaceweather.com/
hot hot hot!
Loud and clear Ulric.
tallbloke says:
June 30, 2010 at 7:49 am
Are there any data on coronal holes coinciding with sunspot locations?
sunspots are often found at the boundaries of coronal holes [helping to provide the magnetic flux that causes the hole to open up]. Coronal holes occur in the middle of so-called solar magnetic sectors. Adjacent sectors have opposite magnetic polarities. The boundary between sectors can be seen in the interplanetary medium as the Heliospheric Current Sheet, which as a ‘sector boundary’ sweeps over the Earth every one to two weeks. The sector boundary can be observed on the Sun as a magnetic ‘neutral line’ separating areas of opposite polarities. Where the change in polarity matches that of the change of polarity between the leading and trailing polarities of spots in active regions is where active regions [and hence spots] most often occurs. This is explained in more detail here: http://www.leif.org/research/The%20Hale%20Solar%20Sector%20Boundary.pdf
Ralph: June 30, 2010 at 4:22 am
That wasn’t condescension. You had asked a convoluted set of questions that indicated a lack of understanding at a fundamental level, and several people were kind enough to try and help with that. Nobody here has any obligation to do that. It is entirely voluntary. You clearly, however, have no appreciation of their efforts, and are rude and demanding to boot. Good luck with your next question. (!)
/dr.bill
Leif Svalgaard says:
June 30, 2010 at 8:05 am (Edit)
tallbloke says:
June 30, 2010 at 7:49 am
Are there any data on coronal holes coinciding with sunspot locations?
sunspots are often found at the boundaries of coronal holes [helping to provide the magnetic flux that causes the hole to open up].
Aha! So, the sunspot’s do have an effect on the corona. Good stuff, and thanks for the link to your 1976 paper. I’m impressed, and I think it will repay a careful reading.
More &^*^%^ homework!
Leif,
You say that a nearby supernova may have caused the 1490 (1460?) spike, yet when I raise the possibility that the irregular timing of galactic supernovae may cause variation in the local interstellear CR flux, you say that occurence of “proximate supernovae does not add to the GCR flux that we can observe”. This seems contradictory.
..you should feel comfortable now knowing that on time scales important to us, the GCR flux is constant.
You haven’t addressed the possibility of changes in our local local interstellar environment affecting the CR flux. As noted earlier, on average it’s thought that there has been up to 20% variablility in the past several million years, and it’s not possible to rule out much larger variability on shorter timescales (eg, of 10^5 years).
According to Florinski and Zank 2005 (“Galactic cosmic ray response to heliospheric environment changes and implications for cosmogenic isotope records”) : “There is evidence that the so-called G cloud, which could become the next solar environment in another 10^3-10^5 years, may be 15 times denser than the LIC.”. Our local interstellar environment may vary on timescales short enough to have an effect even from one millenium to the next.
From the same paper (based on two different CR diffusion models) : “It is seen that the largest possible increase in the rate of cosmogenic isotope production due to galactic environment variability is in the range of 75-300%. This is certainly enough to explain the variability measured in 10Be records.”
We have incomplete knowledge of our local interstellar environment (otherwise we wouldn’t have been surprised by the recent magnetic cloud discovery), and know even less what it was like 1000 years ago, yet we know that the environment can affect the LIS. We don’t know what other events may have occured to influence LIS, such as possibly supernovae or changes in impinging interstellar magnetic fields. I don’t share your certainty that that the interstellar CR flux in the heliospheric vicinity has been constant.
Leif: “But it is hard to believe that that was your only point. Somehow the constancy or lack thereof seems to be important to you for some other aspect, perhaps even the climate.”
We did discuss cosmic rays and climate in another thread – it has no logical bearing on this discussion of Webber & Higbie and LIS.
@Ralph
What force is pulling mass out from the center of the sun?
Just guessing about the anvil. I don’t think anybody knows what exactly the center of the sun is like. But, I suspect the forces acting between atoms there are much stronger than the forces acting between atoms in the anvil.
Perhaps this rather timid illustration of the forces that would be acting to close your hypothetical void will help:
Trailing along here: so sunspots through their coronal effect and on the solar wind might modify how many GCRs hit the earth. And if the local interstellar environment gets juiced periodically by non-galactic CRs then the assumption of steady LIC might be in question. Both these suggest that the data grounding Leif’s belief that the sun hasn’t much effect on climate might be misleading him.
====================
Ralph (8:03 pm) :
The amount of matter on either side of the atom would be the same, but on the side with the void the Sun’s matter/mass would be further away, and so the gravitational effect would be very slightly less. Thus the atom would experience a net gravitational pull away from the void [..]
Actually, the net gravitational force is in fact towards the void/centre.
Your mistake is that you’re only measuring the mass on either side of the atom along a one-dimnensional line. If you include the mass ‘off to the sides’ rather then just directly ahead and behind, you’ll find that the net gravitational force is towards the centre – in other words, measured from the centre, there’s less mass on the far side of the atom than there is on the near side, so the net force is towards the near side (the centre).
re: my 4:29pm just above
in other words, measured from the centre, there’s less mass on the far side of the atom than there is on the near side, so the net force is towards the near side (the centre)
The above isn’t quite correct – the “so” doesn’t follow, since the inverse square of the distances is involved as well, but the calculations do yield a force that’s towards the centre.
tallbloke says:
June 30, 2010 at 1:43 pm
>i>Aha! So, the sunspot’s do have an effect on the corona.
No, you misread that. Sunspots and the corona are generated by the the same thing, the Sun’s magnetic field, but how cold a spot is [I think that was the original question] has no influence per so on the corona, i.e. there is not a signature in the corona saying “here is a cold sunspot”.
oneuniverse says:
June 30, 2010 at 2:53 pm
nearby supernova may have caused the 1490 (1460?) spike, yet when I raise the possibility that the irregular timing of galactic supernovae may cause variation in the local interstellear CR flux, you say that occurence of “proximate supernovae does not add to the GCR flux that we can observe”. This seems contradictory.
First, “I” don’t say so; some people speculate so. This would be a very short-lived effect if it is a nearby supernova [and none is known to match]. The GCR flux we see is the integrated effect of perhaps tens of thousands of supernova, most at vast distances and we see no spatial variation [the flux is the same in all directions, expect for the effect[s] that are due to the processes in the solar system. There is, for example, a diurnal effect due to the rotation of the Earth [same process that makes it seem that there is more traffic on a highway coming towards you than going away fro you]. Since there is no spatial variation it is most unlikely that there would be a temporal variation [as it would vary unevenly across the sky].
..you should feel comfortable now knowing that on time scales important to us, the GCR flux is constant.
You haven’t addressed the possibility of changes in our local local interstellar environment affecting the CR flux. […] Our local interstellar environment may vary on timescales short enough to have an effect even from one millenium to the next.
I did address that, but let me repeat: we are talking about tens of thousands of years, abnd BTW, we do know where the clouds are in our interstellar neighborhood.
This is certainly enough to explain the variability measured in 10Be records.
Not on the shorter time scale we are talking about.
I don’t share your certainty that that the interstellar CR flux in the heliospheric vicinity has been constant.
Fair enough. But if it is not, then argument that solar activity [through] variation of GCR modulation is the dominant driver of climate falls on its face, as the flux is determined outside of the solar system.
oneuniverse says:
June 30, 2010 at 3:07 pm
it has no logical bearing on this discussion of Webber & Higbie and LIS.
Perhaps not [except that it could color your view of things]. As far as W&H are concerned, I [and most people having studied this carefully over last half century] find their argument compelling. but, hey, there are people out there that think to sun is hollow, that the Universe is 6000 years old, etc, so I guess your opinion might deviate as well from that following from W&P’s careful study.
kim says:
June 30, 2010 at 3:27 pm
Both these suggest that the data grounding Leif’s belief that the sun hasn’t much effect on climate might be misleading him.
Actually no: if the GCR flux is an unknown mixture of galactic and solar causes, then people that claim [and there are such, believe it or not] that there is a perfect, compelling, obvious, clear, increasingly evident, robust, etc] correlation between solar activity and climate are in trouble, because that leaves no room for the galactic variation.
oneuniverse says:
June 30, 2010 at 2:53 pm (Edit)
Leif,
You say that a nearby supernova may have caused the 1490 (1460?) spike, yet when I raise the possibility that the irregular timing of galactic supernovae may cause variation in the local interstellear CR flux, you say that occurence of “proximate supernovae does not add to the GCR flux that we can observe”. This seems contradictory.
According to Florinski and Zank 2005 (“Galactic cosmic ray response to heliospheric environment changes and implications for cosmogenic isotope records”)
Excellent, thanks for the link to the paper.
As a matter of interest, a pretty good curve fit to the 14C record (which seems to track 10Be pretty well) can be achieved with just two sine waves in combination. One on a frequency of 2245 years, a well known solar system angular momentum tradeoff cycle involving the gas giants, the other at a frequency of 6000 years, origin as yet unknown (to me anyway).
Why small perturbations in the orbital elements of the planets might affect the levels of 10Be depostion on Earth I’m not sure, but I thought it worth noting in case someones light comes on about it.
tallbloke says:
June 30, 2010 at 10:20 pm
As a matter of interest, a pretty good curve fit to the 14C record…
Which record? corrected for the variation of the geomagnetic field?
well known solar system angular momentum tradeoff cycle
There isn’t any tradeoff of angular momentum as we have discussed so many times.
Leif Svalgaard says:
June 30, 2010 at 10:26 pm (Edit)
tallbloke says:
June 30, 2010 at 10:20 pm
As a matter of interest, a pretty good curve fit to the 14C record…
Which record? corrected for the variation of the geomagnetic field?
You have another 10,000 year proxy for changes in the geomagnetic field?
There isn’t any tradeoff of angular momentum as we have discussed so many times.
I’m not talking about the solar system as a whole, I’m talking about the tradeoffs between the gas giants which produce perturbances such as the 2245 year cycle in the length of N+U synodic periods.
tallbloke says:
July 1, 2010 at 4:02 am
“corrected for the variation of the geomagnetic field?”
You have another 10,000 year proxy for changes in the geomagnetic field?
Yes, but you dodged the question…
gas giants which produce perturbances such as the 2245 year cycle in the length of N+U synodic periods.
Whatever the angular momenta of the gas giants are, they have no influence on the cosmic ray modulation.
How about switching to the current spot?
It’s EIT signatures (171, 195, 284), X-ray and just about everything else are extremely weak, but it has a magnetogram and continuum signature that is unmistakable.
rbateman says:
July 1, 2010 at 9:00 am
How about switching to the current spot?
Not quite sure what you mean. Perhaps a discussion of 1084?
It’s EIT signatures (171, 195, 284), X-ray and just about everything else are extremely weak, but it has a magnetogram and continuum signature that is unmistakable.
The layman’s count says it a record-maker so far for SC24.
tallbloke says:
June 30, 2010 at 1:43 pm
Sunspots and the corona are generated by the the same thing, the Sun’s magnetic field, but how cold a spot is [I think that was the original question] has no influence per se on the corona, i.e. there is not a signature in the corona saying “here is a cold sunspot”.
However, when new magnetic flux emerges [e.g. a new spot] it can have a dramatic influence. See this nice piece:
http://msslxr.mssl.ucl.ac.uk:8080/SolarB/nuggets/nugget_jul01.jsp
tallbloke says:
July 1, 2010 at 4:02 am
“corrected for the variation of the geomagnetic field?”
You have another 10,000 year proxy for changes in the geomagnetic field?
Here:
http://www.leif.org/research/10Be%20Flux%20and%20Geomagnetic%20Field%20Strength%2060k%20Years.png
Leif Svalgaard says:
July 1, 2010 at 9:29 am
rbateman says:
July 1, 2010 at 9:00 am
How about switching to the current spot?
Not quite sure what you mean. Perhaps a discussion of 1084?
——————-
Yes, please, we need to change the channel in here.
Let’s dissect 1084 and see what makes it tick.
I know this 1084 is a great looking spot, but the underlying EIT’s from SOHO are those of a plage region (and weak at that).
I believe you mentioned something about unipolar spots some time ago.
rbateman says:
July 1, 2010 at 12:31 pm
Yes, please, we need to change the channel in here.
Let’s dissect 1084 and see what makes it tick.
One thing that is clear is that it does not have a strongly twisted and irregular magnetic field, which is a pre-requisite for stronger activity [CME, flares, etc]. Also, there are no other spots nearby to disturb it, so it will sit there and slowly spread and eventually decay.
Leif Svalgaard says:
July 1, 2010 at 12:51 pm
Oh, thank you. This is much better.
How often do these non-twisted and non-irregular field spots show up?
If you know of a way to pinpoint other instances of them back to 1996, I would like to look them up and see if they too have very weak EIT signatures.