modest temp increase=irreversible loss of ice caps:

@sonhouse said
If there was a planet opposite the sun it would have been discovered long ago because of the perturbations of the orbits of the other planets.
That tired old hayseed theory has been rebuked ages ago. If an Earth sized body was actually in orbit 180 degrees out of our planet it would have been actually photographed by probes already, like voyager which took images of all t ...[text shortened]... s of the solar system in one image at one point and there was no planet 180 degrees out from Earth.

It was a joke, dude. I wasn't serious. You could have gotten a clue when I asked if you were done laughing.

I was demonstrating how unlikely such an assertion is.

@deepthought said
See e.g.

https://en.m.wikipedia.org/wiki/VSOP_(planets)

For a description of one of the models. The aspidal precession of the orbit of Mercury is one of the tests of General Relativity.

You are clutching at straws.

I was joking. What is wrong with you people?

@metal-brain said
I was joking. What is wrong with you people?

I wasn't responding to the planetary alignment stuff.

So, I take this to mean that you accept that the Earth's orbital parameters change in a predictable way due to perturbations from other planets and so forth. You are disputing that the resultant change in insolation (and specifically seasonal insolation) is sufficient to move the Earth in and out of glaciation. Is this a fair statement of where we are in this.

@deepthought said
I wasn't responding to the planetary alignment stuff.

So, I take this to mean that you accept that the Earth's orbital parameters change in a predictable way due to perturbations from other planets and so forth. You are disputing that the resultant change in insolation (and specifically seasonal insolation) is sufficient to move the Earth in and out of glaciation. Is this a fair statement of where we are in this.

Are they predictable? I accept some degree of perturbations, but I have not seen any proof of predictability. If there were confirmation of the theory I would think we would have found out by now. You seem to think someone else has already confirmed the theory, but I doubt that.

If it is as predictable as you imply, show me the proof.

@metal-brain said
Are they predictable? I accept some degree of perturbations, but I have not seen any proof of predictability. If there were confirmation of the theory I would think we would have found out by now. You seem to think someone else has already confirmed the theory, but I doubt that.

If it is as predictable as you imply, show me the proof.

For pities sake, they discovered Neptune on the basis of anomalies in the orbit of Uranus. How to do the calculations was worked out in the 19th Century. Astronomy is a very precise science.

Here is a link to a paper that presents a model.

https://www.aanda.org/articles/aa/full/2004/46/aa1335/aa1335.html

@deepthought said
For pities sake, they discovered Neptune on the basis of anomalies in the orbit of Uranus. How to do the calculations was worked out in the 19th Century. Astronomy is a very precise science.

Here is a link to a paper that presents a model.

https://www.aanda.org/articles/aa/full/2004/46/aa1335/aa1335.html

That has nothing to do with it. If there is no proof just admit it. It is a theory and nothing more. Nobody can verify a significant enough change to cause an ice age.

@metal-brain said
That has nothing to do with it. If there is no proof just admit it. It is a theory and nothing more. Nobody can verify a significant enough change to cause an ice age.

Here is a presentation of another model.

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.geosci-model-dev.net/7/1051/2014/gmd-7-1051-2014.pdf&ved=2ahUKEwi5-P28sp3fAhWvTBUIHeLtARM4FBAWMAB6BAgEEAE&usg=AOvVaw1kISydDXp1y_1RwePkKjZh

@deepthought said
Here is a presentation of another model.

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.geosci-model-dev.net/7/1051/2014/gmd-7-1051-2014.pdf&ved=2ahUKEwi5-P28sp3fAhWvTBUIHeLtARM4FBAWMAB6BAgEEAE&usg=AOvVaw1kISydDXp1y_1RwePkKjZh

It would take me a very long time to read the whole article, probably weeks so I read parts here and there. I read the "concluding remarks" part at the end hoping it would give me their conclusion to save me a crap load of reading, but there was no conclusion that I could make out from it.

The article mentioned the 3D orbits of the planets just as I had been hoping for so I became hopeful that they had good insight to the orbital aspect of the Milankovitch cycle. I didn't get that at all.
The article addresses all 3 aspects of Milankovitch's cycle theory. This is nice that they covered everything, but it makes the article that much longer and harder to find the relevant info to the orbital change aspect.
I'm not sure the article establishes anything to verify the orbital part of Milankovitch theory. I just cannot find it and it would take me weeks of reading which could very well lead me to nothing relevant to our conversation here.

Have you read much of it?

@metal-brain said
It would take me a very long time to read the whole article, probably weeks so I read parts here and there. I read the "concluding remarks" part at the end hoping it would give me their conclusion to save me a crap load of reading, but there was no conclusion that I could make out from it.

The article mentioned the 3D orbits of the planets just as I had been hoping for ...[text shortened]... h could very well lead me to nothing relevant to our conversation here.

Have you read much of it?

Not thoroughly, I'd suggest just reading the introduction, which is fairly human understandable and gives a reasonable historical perspective. I'm having trouble finding an article that talks solely about orbital prediction and doesn't try to calculate insolation as well. Ideally I'd find an article that compares a model with actual astronomical data - we've a few hundred years of observations and 150 odd years of photographic observations, which should be enough to verify the predictions of the model.

Note that the model in this paper has a rather coarse grained (500 year) step size. But since they were talking about running it on a DEC Alpha I'd imagine that there's something more recent with better precision.

@deepthought said
Not thoroughly, I'd suggest just reading the introduction, which is fairly human understandable and gives a reasonable historical perspective. I'm having trouble finding an article that talks solely about orbital prediction and doesn't try to calculate insolation as well. Ideally I'd find an article that compares a model with actual astronomical data - we've a few hundr ...[text shortened]... bout running it on a DEC Alpha I'd imagine that there's something more recent with better precision.

I would be most interested in how the orbit reverses back. Even if I accept Mars, Jupiter and Saturn lining up in the right 3D alignment how can the inner planets have a similar pull to reverse it? More importantly, the inner planets would probably be aligned more often. How would that fit into a 100,000 year cycle? It doesn't seem to fit at all.

@deepthought said
For pities sake, they discovered Neptune on the basis of anomalies in the orbit of Uranus. How to do the calculations was worked out in the 19th Century. Astronomy is a very precise science.

Here is a link to a paper that presents a model.

https://www.aanda.org/articles/aa/full/2004/46/aa1335/aa1335.html

https://solarsystem.nasa.gov/planets/hypothetical-planet-x/in-depth/

Does that mean you are confident another planet beyond Neptune (planet x) is in our solar system?

@metal-brain said
https://solarsystem.nasa.gov/planets/hypothetical-planet-x/in-depth/

Does that mean you are confident another planet beyond Neptune (planet x) is in our solar system?

I'm reading the paper, I'll tell you what I think when I've finished it - but as long as it's distant enough, so there's a good reason it's not been spotted, I don't see why not.

@deepthought said
I'm reading the paper, I'll tell you what I think when I've finished it - but as long as it's distant enough, so there's a good reason it's not been spotted, I don't see why not.

Are you sure it is distance? Seems to me the planet is dark and that is why it is hard to see, assuming it exists.

https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets

Planet X is supposedly larger than dwarf planets and we have found plenty of those.

@metal-brain said
Are you sure it is distance? Seems to me the planet is dark and that is why it is hard to see, assuming it exists.

https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets

Planet X is supposedly larger than dwarf planets and we have found plenty of those.

Eris was only spotted quite recently and it is larger than all the other known dwarf planets. I've read the paper now, their argument looks fairly convincing and they can explain other features of the outer solar system. If they can narrow down it's orbit enough then it should occlude stars, so one could look for that. I'll believe it when they've spotted it, but I think it's fairly likely.

@DeepThought

Coming soon.

https://www.pbs.org/wgbh/nova/video/pluto-and-beyond/