Solar system motions

  • Thread starter maurol2
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  • #26
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The Moon orbit is turning more eccentric:
"Williams J.G., Boggs, D.H., 2008, paper presented at 16th International Workshop on Laser Ranging 13-17 October 2008 - Poznań , Poland"

This is consistent with an acceleration of the Earth. Which is in turn consistent with an acceleration of the Sun.
These accelerations would also be consistent with an increase of the AU, so the increase of the eccentricity of the Moon and the increase of the AU could have origin in the same phenomena: the Sun's acceleration.

It could be interesting to calculate the Sun's acceleration in the direction of Sun's actual motion towards the solar apex, taking as a basis the Moon's change of eccentricity.
 
  • #27
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This is consistent with an acceleration of the Earth. Which is in turn consistent with an acceleration of the Sun.
Show me the numbers. I'm not convinced :-) :-)

One of the papers on planet X that you cited goes through the calculations that you need to make in order to figure out the effect of accelerations on orbits.

These accelerations would also be consistent with an increase of the AU, so the increase of the eccentricity of the Moon and the increase of the AU could have origin in the same phenomena: the Sun's acceleration.
To make a case like that you have to present actual numbers, and demonstrate if there is X amount of acceleration of the sun you end up with X increase in eccentricity of the moon and Z increase in earth's orbit. You then also can try to figure out that it results in effect A, which no one has looked for. Also you have to figure out how to explain the millisecond pulsars.

Now it would take about six months to work through all of the numbers, but if you do it and it ends up that all of them fit, then that's worth a paper. My guess is that once you work through the numbers, you'll find that an acceleration that causes the moon's eccentricity to behave in one way will cause the AU to behave in another. If that starts to happen, then you have to figure out how to turn lemons into lemonade.

The problem is that without doing actual calculations then anything is possible. That's why numbers are important in this game.

There are some practical reasons for getting this all right. Figuring out whether or not an asteroid is going to hit the earth and where exactly it's going to hit requires extremely high precision orbital predictions. If you figure out that an asteroid is going to hit the earth, then the next thing to do is to figure out what direction to "nudge" it so that it gets out of the way.

It could be interesting to calculate the Sun's acceleration in the direction of Sun's actual motion towards the solar apex, taking as a basis the Moon's change of eccentricity.
I think there is enough information in the papers that you've cited to do that calculation, although doing it and getting it write is going to be *HARD*.

Also you need to read up more on the limits of acceleration of the solar system. If the *only* thing that puts limits on the solar system acceleration is miliisecond pulsars, then this would be easy to "break." On the other hand, I suspect that if you do a literature search you'll find a dozen other tests that create limits. Even if you don't find anything, you'll have to think of some on your own.
 
  • #28
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Here's more data on lunar ranging

http://dda.harvard.edu/brouwer_award/BrouwerAward_2006_Williams.pdf [Broken]

Something to point out is that we are talking about a really, really tiny effect (a few mm per year), and looking at the models, there are so many things that could cause the anomaly. It would be interesting to look through everything and make a list of everything that could cause the issue.
 
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  • #29
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Also there is an effect called the "pigeon poop effect." When Penzias and Wilson first discovered the CMB radiation, their first guess was that they were looking at an equipment malfunction so they went in and among other things cleaned the telescope of pigeon poop. The reason for this is that if you start by claiming that your results may be the result of pigeon poop and then over time it becomes obvious that you really did discover something big, you look like a genius. Conversely, if you start by claiming that you discovered something big, but then it turns out that you didn't, you look foolish.

Something that you have to realize is that observations are hard to do and so is theory. One reason that it's a good idea to go through and try to calculate the effect of accelerations on planetary motions is that you'll find that it's hard to do, and you'll be spending at least a week going through all your calculations to make sure that you didn't mis-add two numbers.

Also observations are also prone to silly errors and mistakes. We are talking about incredibly small differences (a few mm/year) and it's quite possible that it will turn out to be something silly, like some technician on the floor below readjusting their equipment so things move a few mm/year or the size of the building changing in response to the air conditioning system.
 
  • #30
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Also there is an effect called the "pigeon poop effect." When Penzias and Wilson first discovered the CMB radiation, their first guess was that they were looking at an equipment malfunction so they went in and among other things cleaned the telescope of pigeon poop. The reason for this is that if you start by claiming that your results may be the result of pigeon poop and then over time it becomes obvious that you really did discover something big, you look like a genius. Conversely, if you start by claiming that you discovered something big, but then it turns out that you didn't, you look foolish.
You're right, of course. The short answer is: I couldn't care less :-)
The long answer is, that I'm not going to do all the calculations, because I don't have the time. I'm just pondering and throwing ideas here, because it looks like a good place to do it(mainly thanks to you, I must say), and the exchange seems useful.
Maybe some other guy at a later time would read this, and could be interested in doing all the number crunching.

Well, let's move on. Here's a related thing I want to mention:
In our recent talk regarding planet X (a talk that was expurgated and where posts were deleted, so I must repeat it here) I mentioned "dark matter" as a possible cause of the Sun's movement, and you said that a black hole would also be noticed, due to gravitational lensing and other effects.
I want to stress that when I mentioned "dark matter", I was talking about an actually unknown or undiscovered aspect of the way gravity(or another force, btw) works, not about a dark companion/black hole. That is, I understand "dark matter" as a way to say that we don't know what gravity is, and even how gravity works at long scales.
Related to that, I want to mention also: If the Sun is rotating around the galaxy at 220 km/s, and the distance to the center of the Milky Way is ~ 26000 light years, and assuming we're orbiting the galaxy in a circle(which sounds like a good approximation) the Sun must be subjected to a centripetal acceleration ac = v^2/r ~= 2 x 10^-10 m/s^2 (btw, this value is less, but close, to the limit based on millisecond pulsars)
Is this centripetal acceleration actually observed?
It could be interesting to analize this centripetal acceleration and its potential relation with the movement towards the Solar Apex, i.e. the movement towards the solar apex as a consequence of a wobbling or oscillation around the main direction of rotation. Picture the Sun and the solar system in a kind of circular(spiral, really) stream (the milky way arm in which are located), oscillating back and forth and up and down while they travel around the center of the galaxy. This would clearly talk about the galaxy as some kind of "sinking hole", and of gravity as a fluid. Maybe the gravity we know, that is, the gravity we tend to associate with matter, is only a part of the total phenomena, and there's another aspect of gravity that is not associated with matter(what we call "dark marker"), and which only manifests itself as a flow affecting the matter we can observe.

Regards,
Mauro
 
  • #31
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Maybe some other guy at a later time would read this, and could be interested in doing all the number crunching.
My guess is that lots of people have already crunched the numbers, and they haven't found anything. If you crunch the numbers and you find something then you publish, but if you do it and you end up with nothing then you have nothing to publish.

I want to stress that when I mentioned "dark matter", I was talking about an actually unknown or undiscovered aspect of the way gravity(or another force, btw) works, not about a dark companion/black hole. That is, I understand "dark matter" as a way to say that we don't know what gravity is, and even how gravity works at long scales.
At large scales. People who do modified gravity theory put into their models the idea that at solar system scales, nothing the propose makes a difference. That's the idea behind f(R) and MOND models. All of them are set up so that at solar system scales, there is nothing weird, because if there were something really weird we would have noticed it. Yes there is an anomaly of a few mm each year, but there is no anomaly that is a few cm per year, and that puts huge limits on what you can get away with.

About centripetal acceleration. It looks like from the numbers that if we are just a bit more accurate about our measurements then we should be able to see some effects from galactic rotation. Also, if you

It could be interesting to analize this centripetal acceleration and its potential relation with the movement towards the Solar Apex, i.e. the movement towards the solar apex as a consequence of a wobbling or oscillation around the main direction of rotation. Picture the Sun and the solar system in a kind of circular(spiral, really) stream (the milky way arm in which are located), oscillating back and forth and up and down while they travel around the center of the galaxy.
This is likely to be what's going on. One thing that would be interesting to look at is to look at models of the suns motion through the spiral galaxy. and see what accelerations there are.

This would clearly talk about the galaxy as some kind of "sinking hole", and of gravity as a fluid. Maybe the gravity we know, that is, the gravity we tend to associate with matter, is only a part of the total phenomena, and there's another aspect of gravity that is not associated with matter(what we call "dark marker"), and which only manifests itself as a flow affecting the matter we can observe.
One thing that about dark matter is that there are a lot of different types of dark matter. Most of the ordinary matter in the universe is dark, and that would certainly have some effect on galactic motion.
 
  • #32
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My guess is that lots of people have already crunched the numbers, and they haven't found anything. If you crunch the numbers and you find something then you publish, but if you do it and you end up with nothing then you have nothing to publish.
Hi twofish-quant.
I'm not so sure about that. These anomalies are relatively recent.
And Iorio in fact did discovered something related to the retrograde perihelion of Saturn. Namely, that it could be explained by a mass outside the solar system, and (perhaps more importantly) if the mass is in the direction of the galactic center, their results are also consistent with MOND.

At large scales. People who do modified gravity theory put into their models the idea that at solar system scales, nothing the propose makes a difference. That's the idea behind f(R) and MOND models. All of them are set up so that at solar system scales, there is nothing weird, because if there were something really weird we would have noticed it. Yes there is an anomaly of a few mm each year, but there is no anomaly that is a few cm per year, and that puts huge limits on what you can get away with.
Again, Iorio apparently explained the anomalous motion of the perihelion of Saturn. This is a tiny effect(and is even yet to be confirmed) and the math is hard, but anyways, the effort loks very worthwhile.

One thing that about dark matter is that there are a lot of different types of dark matter. Most of the ordinary matter in the universe is dark, and that would certainly have some effect on galactic motion.
Dark matter could be not ordinary matter, but something else that we're only expecting to be ordinary matter, due to conceptual constraints.
In my opinion, it's necessary to disassociate gravity from ordinary matter(at least as an avenue for research), to (perhaps) be able to understand what's really going on.
Accumulation and acceleration of matter would then be a consequence of gravity, but gravity would not be a consequence of matter(which is also a logical dead-end, btw).
That is: accumulation/acceleration of matter is a manifestation of gravity, but there could be "gravity"(or something that behaves like gravity) without matter as a cause.
We tend to associate gravity with matter only because we're used to see gravity where there is matter, but, as you said before: most of the "matter" of the universe would not be ordinary matter. This is (at least potentially) equivalent as saying that there exists gravity without a material cause.
 
  • #33
All of them are set up so that at solar system scales, there is nothing weird, because if there were something really weird we would have noticed it. Yes there is an anomaly of a few mm each year, but there is no anomaly that is a few cm per year, and that puts huge limits on what you can get away with.
You forgot the observed secular increase of the AU, inferred to be about 15 cm/yr.

But in general, your line of reasoning is not valid. That is, taking the mainstream model and trying to restrict
alternatives solely from the fact that the remaining anomalies are small, is not a useful exercise. There are
two main reasons for this. First, almost all observational results in astrophysics are indirect, i.e., the raw
data are analysed with some (mainstream) theoretical assumptions assumed to be valid. The numbers
thus obtained and cited as observational facts, are not completely general results, but inferred and theory-
dependent results. That is, change the theory and the numbers may change. This effect must be evaluated
from case to case - no general statements of how any alternative theory affects the results can be made.
Second, mainstream theory includes free parameters, some of which may absorb large effects predicted
from alternative theories. Unfortunately, it's a problem that free parameters may sometimes be treated as
independent facts, blocking the possibility that free parameters can be disposed of and replaced with
something else in an alternative theory.

The bottom line is that a little learning is indeed dangerous. That is, one should certainly study the
mainstream models thoroughly, so that one knows what theoretical assumptions are made when
analysing the data - just to get an idea of how general the results are. But one should also study alternative
models where crucial mainstream assumptions do not hold. Only by doing this can one really get an
impression of the size of effects one may get away with and still being consistent with observations.
If you do this, I believe that you would be surprised.
 
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