Talk:Gliese 581c

GA Review

This review is transcluded from Talk:Gliese 581 c/GA1. The edit link for this section can be used to add comments to the review.

I am reviewing this article.--Redtigerxyz (talk) 10:47, 27 September 2008 (UTC)

GA review (see here for criteria)

1. It is reasonably well written.

   a (prose): b (MoS):

2. It is factually accurate and verifiable.

   a (references): b (citations to reliable sources): c (OR):

   Good work

3. It is broad in its coverage.

   a (major aspects): b (focused):

4. It follows the neutral point of view policy.

   Fair representation without bias:

5. It is stable.

   No edit wars etc.:

6. It is illustrated by images, where possible and appropriate.

   a (images are tagged and non-free images have fair use rationales): b (appropriate use with suitable captions):

7. Overall:

   Pass/Fail:

• The talk page of the article displays a dispute history. I have some concerns about the stability of this article, so i would put this article on hold for a week or so.

To me it seems over 2 months old. Nergaal (talk) 22:37, 27 September 2008 (UTC)

"Oh for heaven's sake... this is not some kind of conspiracy to misrepresent what we know. ...Icalanise (talk) 13:02, 22 September 2008 (UTC)" The last one.--Redtigerxyz (talk) 10:30, 28 September 2008 (UTC)

• There are some images of Gliese 581 c on commons, about how Gliese 581 c looks. [1] Any specific reason they are not included?

Artist impressions do not add that much and rarely rely on comprehensive references Nergaal (talk) 22:30, 27 September 2008 (UTC)

"how it looks"??! - this isn't in your back yard man, no one has "seen" this planet, the artistic impressions that have been added here have time and time again been deleted. GabrielVelasquez (talk) 17:39, 1 October 2008 (UTC)

• "Selected media articles" is not part of standard WP:LAYOUT, should be merged with External links. ALSO wikipedia is not a directory of links, so some of the links can be reduced.

That means a revision of the article because there is a lot of unecessary info there that has fueled speculations in the article editing. GabrielVelasquez (talk) 17:39, 1 October 2008 (UTC)

• • I merged them to Further reading with two sub-sections.-84user (talk) 20:50, 27 September 2008 (UTC)
• The 2 lines "Age"section is a problem. It "can inhibit the flow of the text". Also, "Short paragraphs and single sentences generally do not warrant their own subheading". (WP:LAYOUT) Can the para be merged.
  • I removed the section, it had a deadlink cite and age is not at all certain anyway.-84user (talk) 20:50, 27 September 2008 (UTC)

Please don't just chop off the text. leave it there as hidden for future contribuitors to build onto it. Nergaal (talk) 22:33, 27 September 2008 (UTC)

The section need not be removed. Can be merged with a relevant section or expanded a bit.--Redtigerxyz (talk) 10:47, 28 September 2008 (UTC)

not sure what age is most similar to. Nergaal (talk) 20:10, 28 September 2008 (UTC)

• "It is predicted that tidal heating" By whom. Add name of scientist and preferably use active voice.

now? Nergaal (talk) 22:37, 27 September 2008 (UTC)

• "Several astronomers have suggested": weasel word. Add names. There might be others who differ in opinion.

Thanks for that. I like that you experienced editors are insupport of removing the unecessary spectulation, especially from scientists that have opponents. GabrielVelasquez (talk) 17:39, 1 October 2008 (UTC)

• • I renamed it Future observations and rewrote to reflect cites.-84user (talk) 20:50, 27 September 2008 (UTC)
• There is too much jargon. Can it be simplified? --Redtigerxyz (talk) 12:28, 27 September 2008 (UTC)

do you ahve specific examples? Nergaal (talk) 22:37, 27 September 2008 (UTC)

"HD 209458 b " what is it? "the high planetary albedo" "exoplanet" "tidal heating" "tidally locked" "pseudo-synchronization" "Io". For example, when writing about Io, write Jupiter's moon Io. Most non-expert readers would never known what Io is, but would know what Jupiter is.--Redtigerxyz (talk) 10:47, 28 September 2008 (UTC)

I believe I've fixed these. Nergaal (talk) 20:10, 28 September 2008 (UTC)

RESULT: ON HOLD--Redtigerxyz (talk) 12:28, 27 September 2008 (UTC)

I have noted my attempted improvements above (and see Talk:Gliese 581 c/GA1#GA edit attempts)-84user (talk) 20:50, 27 September 2008 (UTC)

Image:Gliese 581 orbits-redone-again.png needs a caption, is certainly not self-explanatory. --Redtigerxyz (talk) 10:49, 28 September 2008 (UTC)

done Nergaal (talk) 20:10, 28 September 2008 (UTC)

How does it look now? Nergaal (talk) 20:10, 28 September 2008 (UTC)

GA PASS.--Redtigerxyz (talk) 11:38, 1 October 2008 (UTC)

GA edit attempts

The Gliese 581 system is estimated to be from 7 to 11 billion years old. By comparison, our Solar System is estimated to be 4.6 billion years old.

I removed the above Age section because, after finding obspm.fr a deadlink, then finding http://exoplanet.eu/star.php?st=Gl+581 claimed 4.3 Gyr but linked to article on HD 4308, and then finding Selsis estimated 7 to 11 while W. von Bloh writes of an age at "least 2 Gyr" I suspected the age is somewhat unknown at present. I put the 7 to 11 estimate in the parent star article Gliese 581, though.

I also made these edits:

• diff add cite.php to Selsis cites to more precisely point to relevant sections in paper
• diff merge selected media, news and external links into Further Reading

-84user (talk) 20:19, 27 September 2008 (UTC)

I need you to know that this http://exoplanet.eu/ catalog you are referencing is full of errors and gaps in the data, the guy isn't even bothering with Kepler's third law, and I have been able to fill in about three dozen missing pieces of information for my own speadsheet (extrapolation) copy. If you have the planet mass and/or the semi-major axis, the period of the orbit, the star mass, then the one missing can be calculated from the other three. Same with Luminosity-Radius-Temperature of a star. This catalog is constantly changing it's values, I can show you a history of tweeks Jean has made to fix the data. GabrielVelasquez (talk) 17:51, 1 October 2008 (UTC)

Transclusion not working?

I edited the Talk:Gliese 581 c/GA1 sub-article transcluded above, but the changes do not appear on this talk page until I actually edit this talk page (which is the reason for this edit\). -84user (talk) 21:18, 27 September 2008 (UTC)

your browser's cache. Nergaal (talk) 22:42, 27 September 2008 (UTC)

Temperature addition

I noticed that User:142.161.15.88 has added the following to the article: [2] - however I suspect that this is invalid: it doesn't really make physical sense to transfer the addition of temperatures in this way - the underlying principles are albedo, emissivity and various feedback loops, which makes this very dodgy. Personally I think this should be removed, but I've left tags on them for the moment. Icalanise (talk) 09:27, 18 September 2008 (UTC)

It's definately speculation, but so is the official estimate. Is it incorrect? Well, it makes a valid point. I think it would fall under WP:OR unless sourced to something.--Marhawkman (talk) 13:59, 18 September 2008 (UTC)

The thing is whether it makes sense to say that because Earth is 33°C warmer because of a greenhouse effect, a planet with an atmosphere similar to Earth's but receiving a different amount of radiation would also be 33°C warmer. I don't think this makes sense - if you're going to play these games with speculative atmospheres at least do it in terms of albedo and emissivity (which can be entered into the equations in a reasonable manner), which give different results to this simplistic addition. The difference is that one way is an approximation using basic physics, one is not. In a sense, what the addition is doing is equivalent to saying a*x = x+b therefore a*y = y+b, which is not in general true. Icalanise (talk) 15:27, 18 September 2008 (UTC)

It would still follow a similar temperature scale. It allows a quick approximation that's relatively easy fo a lay person to understand. Admittedly 'tisn't 100% accurate but the whole this is based on estimations anyways.--Marhawkman (talk) 11:11, 20 September 2008 (UTC)

I've reworded the paragraph to provide a concrete example of the difference between effective and surface temperatures. I've removed the temperature addition because if we are going to use estimations, they should be physically justifiable. Icalanise (talk) 16:14, 20 September 2008 (UTC)

You are wrong; it doesn't make any less sense than using the Albedos for Earth and Venus. The increases from the green house gases are as much a fact as the Albedos. It is therefore a deception to include the refrenced albedos and not the referenced GHG effect. It amounts to some serious use of weasal words. The GHG increase for the Earth is closer to +32°C and for Venus +435°C. If you use the Albedo for Earth and Venus, then the known GHG increase is just as valid. GabrielVelasquez (talk) 20:54, 20 September 2008 (UTC)

Do you actually know any physics? It is nonsense to suggest that an atmosphere that when given a certain amount of incoming energy raises the temperature by 30°C will also raise the temperature by 30°C when supplied with twice the energy? This is not how the underlying physics works, even to a zeroth-order approximation. The correct way of dealing with this is to put the emissivity into the equation, keep the emissivity constant and then work it out again. To do the tedious derivation, assuming even redistribution of energy over the surface area of the planet:

$P_{\mathrm {received} }={\frac {L_{\ast }(1-A)}{4\pi d^{2}}}(\pi R_{\mathrm {p} }^{2})$

$P_{\mathrm {radiated} }=\sigma T_{\mathrm {p} }^{4}(4\pi R_{\mathrm {p} }^{2})\epsilon$

and treating the star as a blackbody gives $L_{\ast }=\sigma T_{\ast }^{4}(4\pi R_{\ast }^{2})$

Equating the received and radiated power gives: $T_{\mathrm {p} }=T_{\ast }\left[\left({\frac {R_{\ast }}{d}}\right)^{2}{\frac {(1-A)}{4\epsilon }}\right]^{\frac {1}{4}}$ which in the case ε=1 is the formula in your reference.

The greenhouse warming amount is thus $\Delta T=T_{\mathrm {p} }-T_{\epsilon =1}=T_{\ast }\left[\left({\frac {R_{\ast }}{d}}\right)^{2}{\frac {(1-A)}{4}}\right]^{\frac {1}{4}}\left(\epsilon ^{-{\frac {1}{4}}}-1\right)$

Or to rearrange to make emissivity the subject: $\epsilon =\left[{\frac {(2d/R_{\ast })^{\frac {1}{2}}\Delta T}{T_{\ast }(1-A)^{\frac {1}{4}}}}+1\right]^{-4}$

Treat an atmosphere as a pair of values (A, ε). Earth atmosphere is (0.3, 0.614). Venus atmosphere is (0.65, 0.0181). We can then work out what the greenhouse warming would be at Earth orbit, Venus orbit and Gliese 581 c orbit...

Greenhouse warming
Atmosphere	(A, ε)	Earth orbit	Venus orbit	Gliese 581 c orbit
		T∗=5780 K, R∗=1 R⊙ d=1 AU	T∗=5780 K, R∗=1 R⊙ d=0.723 AU	T∗=3480 K, R∗=0.29 R⊙ d=0.073 AU
Earthlike	(0.3, 0.614)	32 K	37.5 K	38.4 K
Venuslike	(0.65, 0.0181)	380 K	435 K	444 K

The next level of approximation would be to start modelling albedo and emissivity as functions of wavelength and taking into account the different spectral distributions of the stars... however this simple example illustrates that the naive assertion that an atmosphere acts to raise the planetary temperature by a fixed amount is incorrect. (Note I am not advocating including this kind of derivation or table in the article itself). Icalanise (talk) 01:43, 21 September 2008 (UTC)

Hehe, that was kinda my point. I never said anything about a fixed amount. I said "similar". And your table demonstrated that point nicely. :)--Marhawkman (talk) 10:21, 21 September 2008 (UTC)

Indeed it is similar. My original problem was that the article was saying "Earth is x degrees warmer, therefore Gliese 581c would be the same amount warmer if it had a similar atmosphere." As I have demonstrated, this logic is incorrect, despite the original conclusion not being too far off. The problem was not so much the conclusion itself, the problem was the way it was worded implied an incorrect derivation. It is like saying that because 10 miles is 16 km, you can add 6 to the number of miles to get the number of km, so 15 miles is 21 km - the conclusion is not particularly far off the answer derived by doing things properly, but the logic makes no sense. Icalanise (talk) 10:31, 21 September 2008 (UTC)

when you put it that way it sounds simple to reword the article to give the correct impression.--Marhawkman (talk) 10:52, 21 September 2008 (UTC)

First of all, it seems rather stupid of you to rudely ask if I really know any physics when you were the one who answered the reference desk question I posted Sept 18th about the right coding for this planet temperature formula :$\sigma \cdot T_{\mathrm {p} }^{4}={\frac {\sigma \cdot T_{\ast }^{4}}{4\pi \cdot d^{2}}}\cdot {\frac {4\pi \cdot R_{\ast }^{2}}{4\pi \cdot R_{\mathrm {p} }^{2}}}\cdot \pi \cdot R_{\mathrm {p} }^{2}(1-A_{\mathrm {p} })$

Secondly, that's a lot of work for not so different a result for the Earth factored GHG effect, but you did manage to show that the highter the insolation the higher the increase from GHG effect. regardless of your precision the priniciple is there and I would rather be naive that be accused of perpetrating the deception of calling this planet in the habitable zone by using phony equilibrium temperatures. Yes, I said phony because that formula you confirmed says the Equilibrium temperature for Gliese 581 c should be 64°C not 40°C using Earth's albedo, and should be 13°C not -3°C using Venus's albedo. To check for yourselves this the spreadsheet formula, the planet radius cancels out:

=(((((0.0000000567051)*(3840^4))/(4*PI()*((0.073*149597876600)^2))) * ((4*PI()*((0.29*695500000)^2))/(4*PI()*((11162)^2)))*((PI()*((11162)^2)*(1-0.64))))/0.0000000567051)^0.25

People like you are just doing damage control for the fools who assumed we are stupid and would swallow whatever they publish to hipe this planet as habitable. But you can't get away from the fact that the article is going to read like "we formulate that this planet is habitable, but only you imagine that it is a perfect black body (which plants are not) and only if you imaging that it has no atmosphere (which habitable planets do)" - Selsis et fools. Incidently, you missed that the Venus fact sheet reference you used for Venus' "Equilibrium temperature" has no mention of Venus' "Equilibrium temperature." nor does the Equilibrium temperature article mention "blackbody temperature."

Incidentally, that emissivity idea is so original - Talk:Gliese_581_c#More_accurate_formula. -- GabrielVelasquez (talk) 00:48, 22 September 2008 (UTC)

Oh for heaven's sake... this is not some kind of conspiracy to misrepresent what we know. I myself was one of the people who was pointing out that Gliese 581 c was receiving more radiation than Venus right from the start. I don't think any of the editors here are asserting that habitable (or non-runaway-greenhouse) conditions are likely - we are just pointing out that we have no direct observations, so we cannot entirely rule out these alternative models, yet for some reason that seems to deeply offend you. It is ridiculous that we can't have any kind of discussion of this article without you coming along and starting accusing those who disagree with your absolute assertion that Gliese 581 c is a runaway-greenhouse Venus-style planet of being "damage control" for some kind of conspiracy or alternatively of being sockpuppets. Stop POV-pushing. Stop attacking other editors who disagree with you. Stop accusing people who disagree with you of being sockpuppets. Stop making editing this article a needlessly unpleasant experience for everyone involved. Icalanise (talk) 13:02, 22 September 2008 (UTC)

You're full of cow-cookies; I could just as easily call you a POV-pusher. There is no conspiracy theory here, just stated fact, they made errors and I don't appreciate this article being built on errors. Your analogies don't impress me, they are not fact. How long have you been editing this article really that you can say I just come along. You are the one that has just come along, I know how much bias was in the is article a year ago. J. Langton has just come along and is fond of typing long paragraphs critisizing scientific papers and scientific theory and fellow scientists and I don't see you giving him any warnings or mocking him. I am fully within my rights and duties to make sure relevent perspectives do not get burried or scuttled under. as for the sockpuppet stuff I don't care what you think I care what the admin thinks that investigates the claim once I have finish collecting the evidence. Finally I think it is outrageous of you to act as though you represent everyone else here by talking about your POV and qualifying it with the phrase "for everyone involved." You snidely insinuate that I must not know any physics, but claim I am the one making attacks on people. You can make a tenuous attempt at pretending you know what offends me so you can change the subject but the fact is Equilibrium temperature means nothing on it's own and the speculation on Habitability of this planet in this article tends to ignore reality to promote hype. You resist stating facts to live in that hype reality. My suggestion would be for you to go back to editing with your other user account here, I liked that guy better.GabrielVelasquez (talk) 17:23, 1 October 2008 (UTC)

Very well, I have referred your conduct here to the administrator's noticeboard, since evidently outside intervention is needed. Icalanise (talk) 21:32, 1 October 2008 (UTC)

Calculations in error?

The following statement was inserted into the article by User:GabrielVelasquez and reinserted by User:198.163.53.10, who on the basis of [3] is the same as User:GabrielVelasquez (I'm going to give him the benefit of the doubt and assume he merely forgot to log in, rather than tried to use the IP address of a public library to try and give the illusion of more support for his viewpoint)

All temperature speculations are based on the the temperature (heat from) of the parent star, Gliese 581, and have been calculated in error as no the scientist so far that has touched on the subject has factored in the wide margin of error for the star's temperature of 3432°K to 3528 °K.

I think this is strongly POV (note for example that taking the middle of the range 3480 K, this corresponds to an error of about 1.4%) and does not belong in the article. Icalanise (talk) 22:05, 1 October 2008 (UTC)

(2) Second error is worse:

RfC: Equilibrium Temperature reference is being misued and should be removed

Equilibrium temperature for a planet is the temperature without the atmosphere. The examples that are used when scientist use this kind of comparison is done without the greenhouse gas effect, the planet's results are compared to Earth's Equilibrium temperature, of which all the formulas I have seen all of them put it at about -18°C. I can quote a least one scientist who has published that the atmosphere of Venus is toxic and not habitable. So to calculate the equilibrium temperatuer for Gliese 581 c then use the albedo of a planet like Venus, when the albedo is based on the atmosphere is a contradiction of perposterous perportions. The 0.64 albedo is from Venus' atmosphere, so using a formula that pointedly ignores the atmosphere and adding the albedo of the atmosphere (without factoring in the emissivity) is deceptive and that kind of contradiction should not be allowed the article. If you are trying to get the surface temperature then it would be the emissivity not albedo of the Earth that the comparison should be based on. Selsis et al should be ashamed of themselves for publishing this misleading hype, and it should be removed from the article as cleanly cut as possible. GabrielVelasquez (talk) 20:28, 4 October 2008 (UTC)

Removing Celestia depiction of orbits

The orbits of the planets of Gliese 581 (shown in blue). Gliese 581 c is the middle planet.

Celestia, first of all is not a valid reference, it is rife with errors.
Secondly, the "argument of perihelion" for each these planets is unknown,
so the depiction is no better than science fiction.
GabrielVelasquez (talk) 21:09, 4 October 2008 (UTC)