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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oneuniverse says:
June 29, 2010 at 4:51 pm
There is no evidence that I’m aware of, since we’re not considering 10Be and I assume 14C proxies.
As far as LIS and comic rays are concerned it makes no difference if it is 10Be or 14C.
Given this uneven time distribution, one would expect their effect on local interstellar CR flux to vary.
No, because the supernovae are so far away that the cosmic rays do not travel from the event to the Earth in a straight line, but by a random walk [the diffusion] through the Galaxy taking millions of years and hence averaging over many events, completely obliterating the where and when, leading to a very uniform time and space distribution. This is behind the assumption that the LIS rate does not vary.
Your Philips quote has this: “These events [entering LIS clouds] would play out on time scales of tens to hundreds of thousands of years”. For clarity he means 10,000s to 100,000s of years, so irrelevant for the Maunder Minimum and all the other minima we know of.
My comment still stands:
If you assume (1) [contrary to basic diffusion theory that does not support this assumption] that the Galactic LIS varies such that its variation just explains the variation of temperature [further assuming (2) that the GCR flux is the dominant driver – through clouds or whatever], then, of course, you don’t need the Sun to vary [except for the tiny wiggles caused by the 11-year modulation], so solar activity is then not the climate driver. Perhaps that is what you are saying. Spiral arm related GCR variations on time scales of 100s of millions of years can then also be the driver, again we don’t need the Sun. So, I guess you are now converted to agreeing with me that solar activity is not the dominant driver. This would be a viable theory, especially since grand minima do not correlate with temperatures [slide 20 of http://www.leif.org/research/Does%20The%20Sun%20Vary%20Enough.pdf ].
Personally, I would not subscribe to this because I think the assumptions [(1) and (2)] on which it is based are not viable. But that does not preclude that you would subscribe to those, which, of course, you could [with no complaints on my part]. A hybrid theory is not credible, i.e. that both the Sun and the Galaxy vary in unison, such that they always help each and never cancel out. There are people out there that would argue this silly hybrid, invoking ‘the soul’ of the universe or a holistic connectedness of all things, but I don’t think you are one of them.
oneuniverse says:
June 29, 2010 at 4:51 pm
There is no evidence that I’m aware of, since we’re not considering 10Be and I assume 14C proxies.
Perhaps I misunderstood your statement. I took it to mean ‘we [you and I] are not considering 10Be and I [i.e. you alone] assume we are considering 14C proxie[s]’.
But perhaps you were not considering proxies at all, which means that we have no knowledge [indirect or direct] of GCR flux before 1953, so the whole thing is moot.
oneuniverse says:
June 29, 2010 at 5:33 pm
Leif (2:38 pm) , I’ve assumed neither [1] or [2] in our discussion of Webber and Higbie’s “constant LIS” assumption – your assumptions about my possible assumptions about terrestrial temperature and clouds etc. are not germane.
Then I don’t know what you are claiming. You cannot have it both ways [with integrity intact].
Leif, you write: “No, because the supernovae are so far away that the cosmic rays do not travel from the event to the Earth in a straight line, but by a random walk [the diffusion] through the Galaxy taking millions of years and hence averaging over many events, completely obliterating the where and when, leading to a very uniform time and space distribution.”
Yet as you wrote earlier: “.. [the CR LIS] does not change on short time scales, except for short spikes probably due to a nearby supernova, e.g. in 1490.”
More proximate supernovae will experience less diffusion, therefore variation in the rate of supernovae occurence in the proximate regions will produce LIS variability, while more distant regions will contribute a more constant background.
Leif Svalgaard says:
June 29, 2010 at 5:49 pm
Do we know the speed/range of speeds at which GCR’s travel?
Who measures them?
Leif (5:57 pm) : Your second interpretation was the one I meant.
The 10Be records themselves would be evidence of large variations in the atmospheric, as opposed to interstellar, flux, if it turned out that the concentration of 10Be depostion is mainly determined by the production rate. Given that a significant portion of 10Be is deposited within days of atmospheric residence, and most within 1-2 years (iirc), this may turn out to be the case.
Climatic effects are also only able to redistribute the final place and time of deposition, as far as I’m aware, so increasing the number of 10Be datasets should in theory allow us to some extent to account for the climatic signal, at the expense of spatial and temporal resolution.
rbateman, according to Dr. Mewaldt :
“Most galactic cosmic rays have energies between 100 MeV (corresponding to a velocity for protons of 43% of the speed of light) and 10 GeV (corresponding to 99.6% of the speed of light). “
Leif @ur momisugly 6:04pm: “Then I don’t know what you are claiming. You cannot have it both ways [with integrity intact].”
Difficult to believe that you don’t know this:
My claim concerned Webber and Higbie’s assumption that the interstellar CR flux was the same during the Maunder and Sporer minima as it is now. I think I’ve mentioned that several times, in fact it’s been the only thing I’ve discussed.
Tallbloke:
What would stop the matter on one side of the void being gravitationally attracted to the matter on the other side of the void, causing it to close up?
Once a void had developed at the center of the Sun (or Earth), an atom on the edge of that void would no longer experience symmetrical gravitational forces.
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, tending to make the void stable and potentially even increasing the size of the void. Thus creating a hollow Sun.
Of course I am only envisaging a small void here, in relation to the size of the Sun. I am sure someone could calculate the maximum extent of such a void, until it comes into some kind of equilibrium and stops enlarging.
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Leif:
So the center of the Sun may actually be hollow.
Now you are way out there with some of the other esteemed pseudo-scientists that frequent this blog. For all this is a sad state of affairs.
Sorry Leif, I must protest. I am not a scientist (pseudo or otherwise), I am an intelligent layman with a difficulty understanding a particular point of solar-cosmic science. And I have to say, you are not helping me understand anything here.
a. We have now agreed that matter is weightless at the center of the Sun (not anywhere within the Sun, as that website you linked said).
b. With the many eddies and currents in the Sun’s matter, it is not beyond the realms of possibility that a small vortex or void may be created within this weightless material, right at the center of the Sun (by small, say 100km or so across).
c. Any matter on the edge of this void will experience a stronger gravity gradient on its side of this void (the matter there is closer). The difference would be small, but measurable.
d. Such an asymmetric force would tend to perpetuate the void, so it becomes a stable feature.
e. Nothing you have said prevents me from thinking that this is a perfectly reasonable thought experiment. In fact, you have made no reasonable comment at all.
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@Ralph
The net gravitational field might be zero, but if some void were to magically come into existence there, with the pressure gradient that would result, something would fill that void pretty darn quick, like before it could form.
>>> d. Such an asymmetric force would tend to perpetuate the
>>> void, so it becomes a stable feature.
And as evidence m’lud, I present before the jury the recent case of the Coriolis Force (or effect). The said force is a mere trifle in climatic terms, barely enough to perturb the wings of a butterfly, and yet its constant presence creates and sustains a hurricane. I rest my case.
http://en.wikipedia.org/wiki/Coriolis_effect
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Mike G:
The net gravitational field might be zero, but if some void were to magically come into existence there, with the pressure gradient that would result, something would fill that void pretty darn quick, like before it could form.
The whole point is that there is NO ‘gas’ or ‘matter’ pressure at the center of the Sun.
If the matter at the center of the Sun is weightless, as we have established, then there is no ‘atmospheric’ pressure at the center of the Sun whatsoever (atmospheric pressure being created by gravity). The matter at the center of the Sun is free-floating, and able to form a void at the merest whim (especially when it gets whirled around by Jupiter’s long gravitational tresses). So the void may well be long-lasting, or even permanent, and its maximum size would be interesting to calculate.
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@Ralph
Something about arguing with idiots comes to mind…
But, one more try…
In the cyclone, the rotation is counteracting the tiny pressure gradient. What do you propose is going to counteract the unimagineably large pressure gradient in your sun-void? A tiny gravity gradient?
@Ralph
Maybe a better way to look at this would be to wonder how a void could suddenly form in the center of an anvil?
Let me throw this thought out:
If a star such as the Sun cannot vary, it cannot ascend the H-R diagram.
Whatever spectral type they begin life under, they die under.
If it can go up the H-R diagram, then there are two possible ways.
1.) it ages in a completely smooth fashion.
2.) it varies in a sinewave fashion.
Which one fits the observations?
Ralph: The Hyperphysics website that Leif originally directed you to was dealing with the case of a literally rigid shell, like a steel beach ball. If such an object is put out somewhere in space, far from large bodies, it will create a gravitational field around itself that varies as 1/r² just as if a point mass, of value equal to that of the shell, were located right at the center. But there would only be a non-zero field outside of the shell. Inside of it, the field would be exactly zero at all places, and another tiny ‘test mass’ placed inside of it would feel exactly zero force. This is what is demonstrated on that website, and you can also find it in any college textbook on Mechanics in the section on Newtonian gravity.
If you get that, the rest is easy. A thick shell can be treated as a concentric series of thin shells. Now, since each one would contribute zero field inside of itself, then there would still be zero field in the central void (because it is inside of all of them, and each one has no effect). The field outside of the outermost shell, however, will again be a 1/r² field, but now stronger because there is more total mass involved. The main point, apart from the zero field in the cavity, is that the non-zero field is only due to the amount of material between the center and wherever you are located. Whether it is uniformly distributed, or in a thick shell with a central cavity, or just a very massive thin shell doesn’t matter. You can’t tell from the outside anyway (by gravitational methods), and that’s why we still have lots of uncertainty about the mass distribution inside of the Earth.
Now let’s make the object solid, and put you down in a hole like your mineshaft. Some of the mass is now above you, or equivalently, your are inside of it, and it has no effect on you. When you are part way into a solid object like this, only the mass fraction that is situated between your location and the center will create the overall force on you (i.e. your weight). You will still feel weight, but it will be less than the value at the surface, and it will decrease linearly as you go deeper, becoming zero at the center. In practice, of course, it’s as hot as hell down there, and lots of it isn’t solid, and at very deep levels, the chances of a void lasting a millisecond are practically zero. You’d need a (damned!) rigid shell for that.
That any better?
/dr.bill
Ralph: One last thing – a distribution of charges creates an electric field in much the same way that a distribution of mass creates an electric field, and inside of a shell of charge, the electric field will be zero. That’s why Faraday cages work. Zero electric field means no voltage gradient, so every place inside the shell is at the same potential, and thus you can’t get shocked.
/dr.bill
Leif Svalgaard says:
June 19, 2010 at 1:43 pm
The sunspots are cooler because their magnetic field in the photosphere cools the plasma locally, so the cooler temperature is a consequence of the magnetic. The magnetic field in the corona and solar wind is not influence by any of this, and the reconnection with the planetary magnetospheres equally not, and there is no backward reaction.
If the Corona is not affected, how are we able to see sunspots through the corona?
Ok, Ok, It is a gravitational problem:
One can think of a thick shell of mass, with an empty space in the middle ( hollow earth anyone?).
If the mass is solid, the void could be stable . For the sun this is science fiction, there is no solidity.
Suppose we magically create such a situation at time=0.
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. Photons of course will come immediately and will start creating a gravitational field. One could calculate how long it would take, but I would not think it would take much time to diffuse and finally bring the density to the density of the shell and of course the corresponding to its volume gravitational forces.
oneuniverse says:
June 29, 2010 at 6:22 pm
More proximate supernovae will experience less diffusion, therefore variation in the rate of supernovae occurence in the proximate regions will produce LIS variability, while more distant regions will contribute a more constant background.
The 1490 spike is controversial. It has to be a very near supernova if it is one, but none is known. The particles ejected by a supernova explosion are not GCRs [yet] because they move way to slowly.During millions of years some of these particles will encounter ‘magnetic mirrors’ [tangled magnetic fields] and some will be accelerated by that, each time a little bit more until the particles move almost at the speed of light. This takes time, so proximate supernovae does not add to the GCR flux that we can observe.
The 1490 event is a mystery in any case.
rbateman says:
June 29, 2010 at 6:40 pm
Do we know the speed/range of speeds at which GCR’s travel?
from 50% to 99.999% of the speed of light or something like that
Who measures them?
We measure the energy the GCR [mostly a proton] has, and from that can calculate from special relativity at which speed it must be travelling.
oneuniverse says:
June 29, 2010 at 6:58 pm
Leif (5:57 pm) : Your second interpretation was the one I meant.
The 10Be records themselves would be evidence of large variations in the atmospheric, as opposed to interstellar, flux, if it turned out that the concentration of 10Be depostion is mainly determined by the production rate. Given that a significant portion of 10Be is deposited within days of atmospheric residence, and most within 1-2 years (iirc), this may turn out to be the case.
Climatic effects are also only able to redistribute the final place and time of deposition, as far as I’m aware, so increasing the number of 10Be datasets should in theory allow us to some extent to account for the climatic signal, at the expense of spatial and temporal resolution.
oneuniverse says:
June 29, 2010 at 7:27 pm
My claim concerned Webber and Higbie’s assumption that the interstellar CR flux was the same during the Maunder and Sporer minima as it is now. I think I’ve mentioned that several times, in fact it’s been the only thing I’ve discussed.
Well, in that case the result is clear [I have already given you the reason for that] and you should feel comfortable now knowing that on time scales important to us, the GCR flux is constant. To reiterate: to produce a cosmic ray particles must wander around a lot in interstellar space, thus integrating over space and time producing a constant flux.
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.
Ralph says:
June 29, 2010 at 8:03 pm
Sorry Leif, I must protest. I am not a scientist (pseudo or otherwise), I am an intelligent layman with a difficulty understanding a particular point of solar-cosmic science. And I have to say, you are not helping me understand anything here.
I gave you a link to a thorough and compelling explanation. If you have difficulty understanding the derivation [there is some elementary math in there], several people here can help you.
rbateman says:
June 29, 2010 at 9:21 pm
If a star such as the Sun cannot vary
It does on time scales of billions of years
2.) it varies in a sinewave fashion.
Not quite, but the evolution is not smooth and has several ‘flashes’ and jerks.
tallbloke says:
June 29, 2010 at 9:52 pm
Leif Svalgaard says:
June 19, 2010 at 1:43 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.
Perhaps we should wait another 10 years for Helios to fly through the corona.
Mike G:
Maybe a better way to look at this would be to wonder how a void could suddenly form in the center of an anvil?
An anvil is not fluid in the center, and neither does it have forces pulling outwards from the center, like the Sun has.
.
Dr Bill:
Now let’s make the object solid, and put you down in a hole like your mineshaft. Some of the mass is now above you, or equivalently, your are inside of it, and it has no effect on you. When you are part way into a solid object like this, only the mass fraction that is situated between your location and the center will create the overall force on you (i.e. your weight). You will still feel weight, but it will be less than the value at the surface, and it will decrease linearly as you go deeper, becoming zero at the center. In practice, of course, it’s as hot as hell down there, and lots of it isn’t solid, and at very deep levels, the chances of a void lasting a millisecond are practically zero. You’d need a (damned!) rigid shell for that.
That any better?
No need to be patronising, Dr Bill, this is what I said in my very first post – that matter is weightless at the center of the Sun. We passed that problem days ago, but got no further.
But you still did not answer my primary question – can that weightlessness at the center generate a void.
You said:
“Its hot as hell” – – sorry, irrelevant to the discussion.
“It is not solid” – – never said it was, in fact voids will form more easily in a liquid.
“A void will only last milliseconds” – – Why? Explanation?
The point made by another contributor was that the pressure inside the Sun will prevent a void from forming. This is more logical than your ‘explanations’. The Sun is a containment vessel, with gravity providing the containment and increasing the pressure in the matter in proportion to the distance from the center of gravity.
So it is pressure from the surrounding matter that will prevent a void from forming at the center, even though the central matter is weightless. Correct?
.
Italics error.
Dr Bill:
Now let’s make the object solid, and put you down in a hole like your mineshaft. Some of the mass is now above you, or equivalently, your are inside of it, and it has no effect on you. When you are part way into a solid object like this, only the mass fraction that is situated between your location and the center will create the overall force on you (i.e. your weight). You will still feel weight, but it will be less than the value at the surface, and it will decrease linearly as you go deeper, becoming zero at the center. In practice, of course, it’s as hot as hell down there, and lots of it isn’t solid, and at very deep levels, the chances of a void lasting a millisecond are practically zero. You’d need a (damned!) rigid shell for that.
That any better?
No need to be patronising, Dr Bill, this is what I said in my very first post – that matter is weightless at the center of the Sun. We passed that problem days ago, but got no further.
But you still did not answer my primary question – can that weightlessness at the center generate a void.
You said:
“Its hot as hell” – – sorry, irrelevant to the discussion.
“It is not solid” – – never said it was, in fact voids will form more easily in a liquid.
“A void will only last milliseconds” – – Why? Explanation?
The point made by another contributor was that the pressure inside the Sun will prevent a void from forming. This is more logical than your ‘explanations’. The Sun is a containment vessel, with gravity providing the containment and increasing the pressure in the matter in proportion to the distance from the center of gravity.
So it is pressure from the surrounding matter that will prevent a void from forming at the center, even though the central matter is weightless. Correct?
.