Apparent inconsistencies in our scientific understanding of comets

[JeanTate]

I am starting this thread out of frustration at the lack of relevant content in the The Electric Comet Theory /SAFIRE Part V thread.

Initially that thread - or rather, its predecessors - kept more or less on target, and there were many posts on electric comet models etc, and discussions thereon.

For quite some time now, however, the thread has had ~zero such; rather, ones like this, from earlier today:

also tusenfem.





How long are comet tails again? Cylinders, helical, and currents! Imagine if counter rotation was also discovered...sound familiar.

I hope this thread can be a place to discuss apparent inconsisencies in, and ask questions about, the contemporary understanding of comets. Scientifically.

 

[jonesdave116]

I would add to the above, that quoting models as they were understood in the 1950s is not a valid criticism of current scientific theory re comets. At least let's keep it to post-Halley understanding (1986). At the very least, post-AMPTE (1984-5).

 

[Reality Check]

This may be a quite short thread. I am not aware of any apparent inconsistencies in our scientific understanding of comets. There is the usual scientific debate about whether papers on comets are correct or not.

 

[Sol88]

Ok I’ll post,

(c) Whatarecometsmadeof? At the simplest level, a very basic question is whether comets are mostly ice or mostly rock/dirt/refractory material. Whipple’s [2] model of the dirty snowball, the first quantitative model, envisioned cometary nuclei as mostly ice, although our understanding has been evolving more toward mostly rock, particularly for 67P/C-G for which refractory/volatile ratios as high as 6 have been cited [3,4]. N

Comets: looking ahead Michael F. A’Hearn

Rock or dust?

 

[Sol88]

Maybe you mob could discusss.

Inordertomodeltheoutgassingofacometatarateofn[moleculess1],asphericalexpansionisassumedwherethegasmovesawayfromthenucleusatavelocityofe[m/s].Theneutralsgas,escapingfromthecometwillgetionizedbysolarUVradiationand/orcollisionswiththesolarwindatarateof[s1].Usingthis,theradialdependenceoftheneutralgasdensityncanbeformulatedbytheHaser[1957]model:

Haser model????


How’s that going?

 

[JeanTate]

Ok I’ll post,



Comets: looking ahead Michael F. A’Hearn

Rock or dust?

Neither.

Misunderstanding by you. As was explained in the Electric Comet Theory/SAFIRE thread.

So this post is spam, right?

 

[JeanTate]

Maybe you mob could discusss.

Inordertomodeltheoutgassingofacometatarateofn[moleculess1],asphericalexpansionisassumedwherethegasmovesawayf romthenucleusatavelocityofe[m/s].Theneutralsgas,escapingfromthecometwillgetionized bysolarUVradiationand/orcollisionswiththesolarwindatarateof[s1].Usingthis,theradialdependenceoftheneutralgasdensi tyncanbeformulatedbytheHaser[1957]model:

Haser model????


How’s that going?

What you quote is gibberish. And there is no source given.

Would you care to try again?

Also, who or what is "you mob"?

 

[Reality Check]

Rock or dust?

A lying post from Sol88. This is not any inconsistencies in our scientific understanding of comets.

• Michael F. A’Hearn wrote hundreds of papers on ices and dust comets.
  It is dust.
• It is common for comet researchers to use geology terms about comets made of ices and dust.
  We see the terms rock, bedrock, stone, boulders, etc. applied to ices and dust comets.
  It is dust.
• We have evidence for only 2 comets that those 2 comets are not made of mostly ices.
  Tempel 1 ejecta from Deep Impact was 20% to 50% water and rest dust.
  67P was at least 17% ices and rest dust.
  It is dust.

Michael F. A’Hearn wrote his personal opinion that astronomers are evolving toward comets being more '"rock" than ices.

 

[Reality Check]

Haser model????

A lying post from Sol88. This is not any inconsistencies in our scientific understanding of comets. The 1957 Haser model was a scientific model of the production of daughter products from sublimating ices on comet nuclei.

The "gibberish" Sol88 quoted is consistent and basic science: "In order to model the outgassing of a comet at a rate of n[moleculess1], a spherical expansion is assumed where the gas moves away from the nucleus at a velocity of e[m/s].". In any scientific model there are assumptions that are made to allow predictions from the model. These are explicitly stated so the rational people can understand their effects. It would be insane to have a model that cannot predict anything ! The Haser model in 1957 had the assumption of a spherically symmetric coma. This is mostly correct for most comets. A spherical nucleus will have very uniform outgassing with a small difference between day and night sides that will cancel out as the nucleus spins. That equals a spherically symmetric coma. The approximation will get less correct with less spherical nuclei. There will be interactions with the solar wind. to distort the coma.

See A re-evaluation of the Haser model scale lengths for comets (1985)

 

[jonesdave116]

Maybe you mob could discusss.



Haser model????


How’s that going?

Oh dear. More lying by omission. As has already been made quite clear, with links to the relevant literature, many sophisticated models, based on very accurate shape models, have been used to estimate the gas production from the instruments on Rosetta. For instruments at far greater distance, the Haser model is fine. All measurements have a good degree of agreement.
I'm afraid this is just more of the dishonesty of EU that Tim Thompson highlighted. No science, so they resort to lying and obfuscation. With Thornhill as one of their figureheads, that is not so surprising. He is adept at it. Fortunately, most people aren't stupid enough to be taken in by his rubbish.

 

[abaddon]

Ok I’ll post,



Comets: looking ahead Michael F. A’Hearn

Rock or dust?

False dichotomy.

 

[Sol88]

sorry, copy and paste not working nicely.

In order to model the outgassing of a comet at a rate of n[moleculess1],a spherical expansion is assumed where the gas moves away from the nucleus at a velocity of e[m/s].The neutrals gas,escaping from the comet will get ionized by solarUV radiation and/or collisions with the solarwind at a rate of[s1].Using this,the radial dependence of the neutral gas density n can be formulated by the Haser[1957]model: A Tail Like No Other

Is this still how mainstream work out the "outgassing" rate?

 

[Sol88]

False dichotomy.

c) What are comets made of? At the simplest level, a very basic question is whether comets are mostly ice or mostly rock/dirt/refractory material. Whipple’s [2] model of the dirty snowball, the first quantitative model, envisioned cometary nuclei as mostly ice, although our understanding has been evolving more toward mostly rock, particularly for 67P/C-G for which refractory/volatile ratios as high as 6 have been cited [3,4]. N

what say ye abaddon, Rock or Dust?

 

[Sol88]

Oh dear. More lying by omission. As has already been made quite clear, with links to the relevant literature, many sophisticated models, based on very accurate shape models, have been used to estimate the gas production from the instruments on Rosetta. For instruments at far greater distance, the Haser model is fine. All measurements have a good degree of agreement.
I'm afraid this is just more of the dishonesty of EU that Tim Thompson highlighted. No science, so they resort to lying and obfuscation. With Thornhill as one of their figureheads, that is not so surprising. He is adept at it. Fortunately, most people aren't stupid enough to be taken in by his rubbish.

For instruments at far greater distance, the Haser model is fine???

Just like using Gas laws for plasma, MHD for an overall simple picture of the plasma around a comet.


Problem is, it's led you to believe comets are mostly ice!

but OUR understanding is evolving toward mostly rock.

 

[JeanTate]

Thanks Sol88.

sorry, copy and paste not working nicely.



Is this still how mainstream work out the "outgassing" rate?

What is the source? What do you mean by "mainstream"? Why do you think this is (or may be) an inconsistency?

Remember, this is a thread devoted to scientific understanding. So please, always, provide a source.

 

[Sol88]

There are more than enough mainstream papers to call the mainstream model of icy dirtballs into account!

and when posted 'ol mate JD116 poo poos them. Funny as! The RSI experiment was a classic! Patzold's paper backs A'Hearns statement.

problem is, most posters here cant stand being wrong.

Like the rock/dust issue.

 

[Sol88]

Thanks Sol88.


What is the source? What do you mean by "mainstream"? Why do you think this is (or may be) an inconsistency?

Remember, this is a thread devoted to scientific understanding. So please, always, provide a source.

A Tail Like No Other Martin Volwerk1, Charlotte Goetz2, Ingo Richter2, Magda Delva1, Katharina Ostaszewski2, Konrad Schwingenschuh1 and Karl-Heinz Glassmeier2

Give it a go!

mainstream, YOU, have overestimated Q. Which led you to believe comets MUST be mostly ice.

 

[JeanTate]

For instruments at far greater distance, the Haser model is fine???

Why the triple question marks, Sol88?

Just like using Gas laws for plasma, MHD for an overall simple picture of the plasma around a comet.

Problem is, it's led you to believe comets are mostly ice!

but OUR understanding is evolving toward mostly rock.

(my bold)

Why are addressing this to jd16?

A reminder: this thread is about science, not personal opinions, whether yours or jd16's.

 

[jonesdave116]

sorry, copy and paste not working nicely.



Is this still how mainstream work out the "outgassing" rate?

How many frigging times do you need to be told? No, it is not. Alright? Need the links? Again? And again? And again? Give up.

 

[jonesdave116]

A Tail Like No Other Martin Volwerk1, Charlotte Goetz2, Ingo Richter2, Magda Delva1, Katharina Ostaszewski2, Konrad Schwingenschuh1 and Karl-Heinz Glassmeier2

Give it a go!

mainstream, YOU, have overestimated Q. Which led you to believe comets MUST be mostly ice.

Wrong. Another lie. Do you ever post anything that isn't a lie? Nobody has said for decades that comets are mostly ice. It is your lie.