# Talk:Gliese 581 c

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Gliese 581 c has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Article milestones
Date Process Result
October 1, 2008 Good article nominee Listed
October 26, 2008 Good article reassessment Delisted
April 3, 2016 Good article nominee Listed
Current status: Good article
WikiProject Astronomy / Astronomical objects  (Rated GA-class, Mid-importance)
Gliese 581 c is within the scope of WikiProject Astronomy, which collaborates on articles related to Astronomy on Wikipedia.
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## 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.[1] By comparison, our Solar System is estimated to be 4.6 billion years old.[2]

1. ^ Selsis 3.4
2. ^ Gary Ernst Wallace (2000). "Earth's Place in the Solar System". Earth Systems: Processes and Issues. Cambridge University Press. pp. 45–58. ISBN 0521478952.

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)

I see that the infobox uses exoplanet.eu for four properties. Should we cite papers directly in addition to collators such as SIMBAD and exoplanet? I followed exoplanet's ref to Udry's letter and verified our figures match Udry's table 1 for the eccentric case. However our Time of perihelion was taken from the circular case, a trivial difference. I may as well check the other exoplanet cites now. I also fixed my incorrect diff link above. 84user (talk) 22:06, 4 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)
Transclusions do not refresh in a timely manner, try using the purge action on pages with transcluded elements that have been updated. 70.51.8.75 (talk) 08:49, 6 October 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:
${\displaystyle P_{\mathrm {received} }={\frac {L_{\ast }(1-A)}{4\pi d^{2}}}(\pi R_{\mathrm {p} }^{2})}$
${\displaystyle P_{\mathrm {radiated} }=\sigma T_{\mathrm {p} }^{4}(4\pi R_{\mathrm {p} }^{2})\epsilon }$
and treating the star as a blackbody gives ${\displaystyle L_{\ast }=\sigma T_{\ast }^{4}(4\pi R_{\ast }^{2})}$
Equating the received and radiated power gives: ${\displaystyle T_{\mathrm {p} }=T_{\ast }\left[\left({\frac {R_{\ast }}{d}}\right)^{2}{\frac {(1-A)}{4\epsilon }}\right]^{\frac {1}{4}}}$ which in the case ε=1 is the formula in your reference.
The greenhouse warming amount is thus ${\displaystyle \Delta T=T_{\mathrm {p} }-T_{\epsilon =1}=T_{\ast }\left[\left({\frac {R_{\ast }}{d}}\right)^{2}{\frac {(1-A)}{4}}\right]^{\frac {1}{4}}\left(\epsilon ^{-{\frac {1}{4}}}-1\right)}$
Or to rearrange to make emissivity the subject: ${\displaystyle \epsilon =\left[{\frac {(2d/R_{\ast })^{\frac {1}{2}}\Delta T}{T_{\ast }(1-A)^{\frac {1}{4}}}}+1\right]^{-4}}$
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 :${\displaystyle \sigma \cdot T_{\mathrm {p} }^{4}={\frac {\sigma \cdot T_{\ast }^{4}}{4\pi \cdot d^{2}}}\cdot {\frac {4\pi \cdot R_{\ast }^{2}}{4\pi \cdot R_{\mathrm {p} }^{2}}}\cdot \pi \cdot R_{\mathrm {p} }^{2}(1-A_{\mathrm {p} })}$
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)

no calculations are wrong, the man who wrote this is right and should be listened to otherwise our thoughts of finding new life and ending the sorrow of lonelyness for the human race will grow unbearable for most, thankyou and keep the world updated with the truth. —Preceding unsigned comment added by 78.145.46.179 (talk) 23:05, 11 July 2010 (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)

First off I think it would be wise not to conflate the issue of habitability for humanity, and the generalised definition of habitability that seems to be in use in astrophysics which is the capability of an object to support liquid water, a substance which is required by all known life forms. Your point about the Venusian atmosphere being toxic raises the question "toxic for what?" -- the criteria for the place being pleasant for you or me to go walking around are rather more stringent than allowing the range of environments inhabited by various extremophile life forms.
As for the equilibrium temperature, I think you are mistaken as to what it actually means. The term "equilibrium temperature" has a precise definition and is one that is widely used in this area of astrophysics (also appearing under such names as "blackbody temperature"): from the Selsis paper (page 1374), the equilibrium temperature is:
${\displaystyle T_{\mathrm {eq} }=\left({\frac {S(1-A)}{f\sigma }}\right)^{\frac {1}{4}}}$
Where S is the stellar flux, A is the Bond albedo, σ is the Stefan-Boltzmann constant and f is a factor that represents how much the energy is redistributed around the planet: if the energy is evenly spread, it is 4, if no heat is distributed to the nightside then it is 2. For the former case f=4, this can be rearranged to the formula from Barbieri that you are so fond of quoting. This formula gives you the temperature of a blackbody that radiates the same amount of power as is absorbed by the planet: i.e. one that is in equilibrium with the absorbed radiation. This is the definition of the term, and its meaning is in fact discussed in the Selsis paper on pages 1374-1375:

It is important to discuss the meaning of Teq and the manner in which it can be used to assess habitability. The planet Gl 581c has been widely presented as potentially habitable because one finds Teq ∼ 320 K when calculated using the albedo of the Earth. This conclusion is however too simplistic for the following two reasons:

i) For a planet with a dense atmosphere (an inherent property of a habitable planet), Teq does not indicate any physical temperatures at the surface or in the atmosphere. With albedos of 0.75, 0.29, and 0.22, respectively, and assuming f = 4, Venus, Earth, and Mars have equilibrium temperatures of 231 K, 255 K, and 213 K, while their mean surface temperatures are 737 K, 288 K and 218 K. The two quantities only match, approximately, in the case of Mars, whose tenuous atmosphere produces a greenhouse warming of only ∼5 K.

ii) It can be demonstrated that a necessary (but not sufficient) condition for habitability is that Teq must be lower than about 270 K. If the surface temperature remains below the critical temperature of water (Tc = 647 K), the thermal emission of a habitable planet cannot exceed the runaway greenhouse threshold, ∼300 W m−2 (see Sect. 2.2.1), equivalent to the irradiance of a black-body at 270 K. Therefore, if a planet has an atmosphere and an equilibrium temperature above 270 K, two situations may arise. First, Ts may remain below Tc, but there would be no liquid water at the surface and no or negligible amounts of water vapor in the atmosphere. In a second possible situation, the atmosphere contains considerable amounts of water vapor, but the surface temperature exceeds 1400 K (see Sect. 2.2.1). This would allow the planet to balance the absorbed stellar energy by radiating at visible and radio wavelengths through an atmosphere that is optically thick in the infrared (IR). Both cases would render the planet uninhabitable.

So I don't think you can accuse Selsis et al. of promoting "misleading hype" -- they are in fact arguing against using an equilibrium temperature to judge habitability, except for putting an upper limit on what the effective temperature can be for a habitable planet. Note they explicitly state that having an equilibrium temperature below this limit does not mean that the planet will be habitable either: Venus is a good counterexample because there is a large discrepancy between the equilibrium temperature and the actual surface temperature - note that in fact it fulfils the condition Teq<270 K, and is thus a good example that the criterion, while necessary, cannot be sufficient, as is stated by Selsis et al.. The difference is of course the emissivity - a real planet radiates less efficiently than a blackbody (which represents the most efficient radiator) because of atmospheric effects, so its physical temperature will be greater.
Regarding putting the equilibrium temperature into the article, I think this should be done, as it is what led to the early claims of habitability (which are why the average reader would have heard of this planet in the first place), however misleading those claims were. Nevertheless I think what we should be very careful to do, so as not to be misleading ourselves is to state precisely what the definition of the equilibrium temperature is - note that there are similar examples of temperatures in physics which do not correspond to physical temperatures, such as brightness temperature and effective temperature, which have similar kinds of definition (relating a power to a blackbody temperature). These are not misleading, nor is the term "equilibrium temperature", provided it is stated for the reader who has not come across these terms before what they actually mean. Icalanise (talk) 21:48, 4 October 2008 (UTC)
Yeah sure, and color temperature and photosphere temperature, but you are twisting my words, I didn't say Effective temperature itself was misleading, only the way they have used it by adding the albedo of Venus. Using the albedo of Venus and the greenhouse gas effect of the Venus atmosphere on temperature are two distinct things. nb this article doesn't say that Selsis is using effective temperature to counter habitiablilty, it at one point left it open to that very insinuation with just the (incorrect) temperatures. GabrielVelasquez (talk) 20:39, 5 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)

The depiction of the orbits in Celestia is consistent with the existing data under the assumption that the system is coplanar (which would be the same for any depiction of the orbits). However, for orbital elements Celestia by default assumes that the coordinate system is the ecliptic coordinate system (which makes sense for objects in our solar system), however the orbital elements for stars, exoplanets etc. are given in the sky-plane coordinate system. The transformation between the two is complex (for a start, it depends on where the star is located in the sky) and thus you end up with different values for the orbital parameters which explains the discrepancy between Celestia's orbital elements and those in the catalogues. In Celestia, neither the longitude of the ascending node nor the inclination are specified because they are unknown, so they default to zero (in the ecliptic coordinate system). Since the longitude of perihelion is a compound angle (it is given by the sum of the argument of perihelion and the longitude of the ascending node), and since for a coplanar system the longitude of the ascending node is the same for all planets (similarly the inclination is the same for all planets), the depiction is fine, assuming you don't try and relate the orientation of the plane of the system to the background stars. If you want to check the orbits in Celestia, compare the differences between the arguments of periastron, these are the same as the differences between literature values. (Note that adding a constant angle to argument of periastron is equivalent to rotating the orbit about the normal vector to the plane of the orbit which passes through the star) Icalanise (talk) 22:10, 4 October 2008 (UTC)
Additional disclosure - I am a Celestia developer. Thus I would be extremely interested to know what precisely you mean by "rife with errors". Icalanise (talk) 22:17, 4 October 2008 (UTC)
Sure, so where is the reference for this relating to Gliese 581 c? - You made the picture and so it has to belong in the article? - I believe your disclosure there only makes the point for the pictures removal. It has no referencing, and as others here have been fond of expressing that means it goes. 205.200.236.34 (talk) 04:52, 5 October 2008 (UTC)
Actually, I didn't make that image, so I am not arguing what you think I am arguing. I am merely pointing out that the accusation that Celestia is "rife with errors" is unjustified in this instance. As for referencing, the extrasolar planets datafile in Celestia (extrasolar.ssc, which can be downloaded from the SVN tree at [4]) does provide referencing in the comments at the start of the file, which gives a detailed description of the data sources and the assumptions made there. (This is standard policy in Celestia - always provide a citation for the data source). I'll quote the relevant part for you (this is from revision 4484):
# Catalog of 293 known extrasolar planets.
#
# Data compiled from Butler et al., Catalog of Nearby Exoplanets at:
#     http://arxiv.org/abs/astro-ph/0607493
# supplemented from the Extrasolar Planets Encyclopaedia at:
#     http://exoplanet.eu/catalog.php
# The mu Ara system is taken from Pepe et al., The HARPS Search for Southern Extra-solar Planets at:
#     http://arxiv.org/abs/astro-ph/0608396

Icalanise (talk) 10:11, 5 October 2008 (UTC)
I added the above references on the Wikimedia Commons page of the discussed image. I personally think it is a step to put it back in the article, but before the discussion about the orbital elements assumptions should be added to the image, so that concerns can be settled. --Cyclopia (talk) 13:44, 5 October 2008 (UTC)
New SVG version

Since this image should really be an SVG, I've created a new version of the diagram, with the data derived directly from the Udry et al. discovery paper (this is referenced on the image description page and in the comments inside the SVG file itself - open the original file in a text editor to have a look). Hope it is ok. Icalanise (talk) 13:48, 5 October 2008 (UTC)

Having a SVG is great, however I think the references etc. should be explicit, instead than hidden in the SVG file (where no one would notice nor bother). I've seen there is some reference on the image page: if you can make it more explicit (what is A&A?) and add a link to the journal abstract, is OK. --Cyclopia (talk) 14:18, 5 October 2008 (UTC)
Ok, I've updated the description at Wikimedia Commons, anything else you think should be added? Icalanise (talk) 14:35, 5 October 2008 (UTC)
For me, it's perfect now. --Cyclopia (talk) 15:20, 5 October 2008 (UTC)
Added the new image both to this article and to Gliese 581. --Cyclopia (talk) 15:25, 5 October 2008 (UTC)
So you are saying this accurately depicts the perihelion synchonisation of all three planets orbits: so where is the reference in the article for this again, and why is this image not synthesis?? - it sounds like you are saying the image references itself and that unfortunately does not make the cut. GabrielVelasquez (talk) 19:14, 5 October 2008 (UTC)
I am not saying the image references itself, this would be silly. What I am saying is that the image description page gives the reference used for the depiction of the orbits in the image (this image description page will be visible if you click on the image), and that the reference is also in the SVG file for the image (since SVG is an XML format, you can incorporate comments into the file) - in fact most of the filesize is due to comments which document the generation process in fairly exhaustive detail. You can see this for yourself if you download the full file and open it in a text editor. The reference is the same as the one used for the orbital parameters in this article's infobox, i.e. Udry et al. (2007), Astronomy & Astrophysics 469, L43-L47 "The HARPS search for southern extra-solar planets XI. Super-Earths (5 and 8 M_⊕) in a 3-planet system", specifically the "free eccentricity" solution in Table 1 on page L45. The image does not constitute original research as it is a direct translation of that data into graphical format, using standard geometry and standard Keplerian orbit formulae. Icalanise (talk) 20:12, 5 October 2008 (UTC)
First the reference that is required should also be in the article, like the frame of the picture would be a nice place. and also what you are discribing sounds like systhesis to me. If I started making charts of stuff using Keplerian orbit formulae it would get deleted, just like my insolation charts (even thought there is a whole article on Earth's insolaton) were deleted. Personally I think known data plugged into known formulae should be allowed, I don't even do it myself, Excel speadsheet does the calculations automatically; but why should your work be exempt from this standard and scrutiny. GabrielVelasquez (talk) 20:25, 5 October 2008 (UTC)
I think the problem with your spreadsheet was not the image itself, but the fact there was disagreement on if the formula was actually a realistic model or not -I think it was a consensus problem. There should instead be no disagreement on the fact Keplerian elements correctly describe planetary orbits with extremly high precision, and their graph is the immediate meaning of those elements. --Cyclopia (talk) 01:10, 6 October 2008 (UTC)

GabrielVelasquez, why not file an RfC on this matter if it troubles you so much. Orbit diagrams produced in much the same way have been accepted on other articles about exoplanetary systems for a long time on the Wikipedia, so the matter of whether such depictions should be accepted should be discussed in a more general forum than this article's talk page. Icalanise (talk) 20:35, 5 October 2008 (UTC)

You are trying to side step the issues I have raise: if there is policy against it you can't ignore/violate the policy. Bringing other articles in the whole of the encyclopedia in line with policy is not a challange that I care to spend time on. You'll notice I am editing here, right now. You have not convinced me how this image is not synthesis, and that's while giving you the benefit of the doubt. GabrielVelasquez (talk) 20:47, 5 October 2008 (UTC)
by your rational, images like this one (not this data) could and should be constructed everywhere and anywhere with no standard or policy:

GabrielVelasquez (talk) 20:57, 5 October 2008 (UTC)

Evidently we need another opinion here. I have therefore left a message on WT:ASTRO. Icalanise (talk) 20:56, 5 October 2008 (UTC)
The WP:OR actually says "Synthesis occurs when an editor puts together multiple sources to reach a conclusion" and also it says "Wikipedia does not publish original research or original thought. This includes unpublished facts, arguments, speculation, and ideas; and any unpublished analysis or synthesis of published material that serves to advance a position."
So I have two questions:
1) What conclusion stems from this image?
2) What unpublished facts, arguments and ideas does it contain?
3) What position is advanced by this image?
If the image makes not conclusion, does not advance any position with unpublished facts, arguments and ideas, it is not an original research. Ruslik (talk) 08:49, 6 October 2008 (UTC)

This is not OR. Plugging known data into established formulas is not OR, despite the comment by GabrielVelasquez above. It never has been. People output such graphics all the time on Wikipedia. The broad, established consensus is that this is ok and not OR. Whether it's relevant or interesting is another issue. --C S (talk) 09:58, 6 October 2008 (UTC)

I agree with Ruslik. It's the same data in a different format. There isn't any reason not to use the chart.--Marhawkman (talk) 12:12, 6 October 2008 (UTC)
Can I get a clarification here -- by the "chart" are you referring to the orbit diagram, GabrielVelasquez's temperature table, or both? Icalanise (talk) 12:16, 6 October 2008 (UTC)
the orbit map/s.--Marhawkman (talk) 12:21, 6 October 2008 (UTC)

Note that there is a specific exception in the NOR policy for images: "A notable exception to this policy concerns images: Wikipedia editors are encouraged to take photographs or draw pictures or diagrams and upload them,..." (WP:OI). Of course, ff there are disagreements about the accuracy of a diagram, they have to be resolved by discussion; there's no free pass to put in bad diagrams. But "original research" is not forbidden in diagrams the same way it is in text; if there is agreement to use a particular original image, then the policy permits it. — Carl (CBM · talk) 13:49, 6 October 2008 (UTC)

I am personally divided on this, I have nothing against an orbit image if it is accurate, and I have read above that assumptions are being made about the orbit data for the final orbit image. I have not received a clear answer about the data on the orbits, only had it clouded further. I don't want a misleading image of the orbits in the article. If it is not possible to show that the timing of perihelion of the planets then the whole obit image idea is a fraud because they are not perfect circles and are going to end up some what like ellipses and they are aligned in some way with the other planets perihelion points that you are misrepresented. Also it seems I am going to have to reread everything (policies and peer reviewed papers) on my day off to be sure I'm not just being told what I want to hear, Know data and Known formulas don't constitute Original Research. I doubt everyone is going to agree with that, it sounds like a loophole interpretation. But that would effectively put back some interesting things into this article. GabrielVelasquez (talk) 17:46, 7 October 2008 (UTC)
I don't know if I understood correctly, but your concerns seem related 1)about the data sources for the image 2)about the fact the image can contain some information that is actually not known, like the orientation of the perihelia. About point 1, I think Icalanise provided full references for the image, and they have been put in the relevant place (the Wikimedia Commons image page). About point 2, well, I try to make myself clear with an analogy. Imagine we're discussing about an extinct dinosaur, and someone posts a scientifically sound colour reconstruction of the dinosaur. What we know of the dinosaur, technically, is bones: any colour is surely fantasy. However I would not find the whole image "a fraud", because most of the reconstruction is done from data -simply, there is missing information that somehow has to be filled in. I think it is the same here. We have most of the necessary data for orbital depiction. We lack some detail, but in my opinion the visual help the image gives on immediately understanding, for example, eccentricity and distance from the star, makes it worthwile despite any concern with the actual orientation of perihelia. Of course I am all for clarifying in the legend that the actual orientation of perihelia (or whatever) is not known, so that there is no ambiguity to the reader. --Cyclopia (talk) 18:21, 7 October 2008 (UTC)
Under the assumption that the orbits are coplanar and rotate around the star in the same sense (which are reasonable assumptions from stability arguments and planet formation theories - plus our own system and PSR B1257+12 are known to be coplanar, as well as Epsilon Eridani - our own system is also known to have the eight major planets revolving in the same direction), the relative orientation of the perihelia with respect to each other is accurate and is given by the parameter ω in the orbital elements given in the reference stated (which is in the infobox in this article under the name "longitude of periastron"). The position of the planets in their orbits with respect to their perihelia can be accurately computed for a given time from the value of the time of periastron for each planet which is given in the reference stated. The absolute orientation of the perihelia in 3D space is indeed unknown, but it does not affect the accuracy of the diagram as no orientation with respect to external points (e.g. the Sun, the galactic centre) is specified. Icalanise (talk) 19:41, 7 October 2008 (UTC)
Very good. The coplanarity assumption could maybe be explicited in the figure page, just to settle issues. By the way, what you said about the amount of information that can be gathered by mean of radial velocity/Doppler spectroscopy is interesting in itself -at least, I didn't know that! If you can reference it, why not adding it to one of these two articles? --Cyclopia (talk) 20:13, 7 October 2008 (UTC)
I've amended the description page at Wikimedia Commons to more clearly state the assumptions being made and to provide justification for why they are reasonable assumptions to make given the current state of knowledge. Icalanise (talk) 21:00, 7 October 2008 (UTC)
Wonderful work! Thanks.--Cyclopia (talk) 21:47, 7 October 2008 (UTC)

## (paraphrase) "Known Formulas used with Known Data is not OR."

I'm looking at the above support for the orbit diagram and the discription fits the chart as well. I think the chart of Albedo/Emissivity temperature is less speculative that the assumption of the plane of the orbits. I'm not saying that one is worth more than the other they are different sets of data, although someone mistook them for the same, all I am saying is if there is no prohibition against in then why not use it, the known formula being from NASA and the know data being from Gliese 581 c, and call the range of possibilites known Albedo and Emissivity. GabrielVelasquez (talk) 00:58, 16 October 2008 (UTC)

Maybe more than "known formula" , "universally accepted formula" would be better. What I mean is: NASA is surely a good source, but if there has been discussion on how to apply such a formula by mean of professionals here, it probably means that that formula is not universally accepted -it seems to me (I may be wrong) that, given the previous discussion on it and this article, it is just an approximation that may be useful somewhere but not in all cases, and that there is too much uncertainity on the planet conditions to be sure if using it or not. Listen me carefully: I personally think too that our little Gliese 581 c is utterly inhabitable and that runaway greenhouse effects are probable. I just think these opinions, even if reasonable, should be mentioned and discussed, but cannot not be given as certainity. Using formulas etc. gives us a false sense of confidence on something on which we know nothing -after all who knows if little green men from another planet have installed a giant fridge on its surface and terraformed it? (ok, just kidding here, but you understand what I mean)- while on orbits at least we have some data. --Cyclopia (talk) 07:17, 16 October 2008 (UTC)
Maybe if the chart was redone to show the range of possibilities based on the data we have?--Marhawkman (talk) 10:18, 16 October 2008 (UTC)
The fact is, the range is endless. What if something impacted Gliese 581 c recently and the whole planet is now on fire? What if some oddball geological process we are not aware of (after all, we never dealt with a super-Earth), or (again) an impact striped off all atmosphere from the planet for some reason? Also, what is its axial tilt and precession? Its history? We can have some range but based on very poorly-based assumptions, since -as far as I know- we have no idea of the range of possible geologies and atmospheres for such an object. Earth is the largest rocky object known in the Solar System and it displays unique phenomena like plate tectonics, surface water oceans and (of course) life. Its climate depends on all of that -after all, Venus is slightly smaller yet underwent runaway greenhouse effects while Earth did not, probably thanks to plate tectonics. Even for smaller bodies, of which there is plenty in our planetary system, we are everyday discovering exceptions and unique behaviours (see Enceladus). Predicting anything on Gliese 581 c is simply impossible until we find a way to probe something about the object -reasonable hypothesis can be made, but I think in this case we should stick with known scientific literature, or we will really find ourselves into OR. --Cyclopia (talk) 12:42, 16 October 2008 (UTC)
Ah, so the chart doesn't really display known data. It shows our best guess based on practically nothing.--Marhawkman (talk) 09:51, 17 October 2008 (UTC)
Not so harsh :) - it shows what is probably a reasonable but unproven guess, given a lot of assumptions. --Cyclopia (talk) 12:59, 17 October 2008 (UTC)
To answer User:GabrielVelasquez: the assumption of the coplanarity is based on dynamical simulations and on the observation that, when it is possible to find this datum, all planetary systems investigated so far are coplanar. So there is some ground to assume that. On the chemical composition, atmosphere, geology etc. of super-Earths we have a LOT of parameters of which we basically know zero, as I tried to explain above. So the two situations are really different. --Cyclopia (talk) 12:45, 16 October 2008 (UTC)
There is the issue that the table attempts to derive an unknown quantity and does not provide any physical justification for any of the input quantities. If I were to pick a combination of A and ε from the table, would it be possible to state whether this is a plausible combination of values for this planet - is there an atmosphere/surface combination for which it would be reasonably stable, and can you provide a referenced source to justify that? Without the physical justification, the table strikes me as a fairly roundabout way of stating that with the data we have and without making any assumptions whatsoever about the planet and its atmosphere, we cannot say anything about what the temperature is going to be. Simply put, figuring out planetary surface conditions requires non-trivial calculations! As for this particular table, time for me to nitpick: there is the issue of significant figures, and the question of just what is being calculated. A formula where all the constants have been substituted in is not particularly good: at best it forces the reader to search through various lists of physical constants, unit conversion factors etc. to find out just what the constants are in the formula, reconstruct the original equation and then figure out if the original equation is reasonable and whether the values you have got out of it are correct. Otherwise it might as well be unreferenced. Icalanise (talk) 19:31, 17 October 2008 (UTC)
You're right there is a lot in that chart that could be clarified and referenced (as you did within the orbit chart file), but I disagree that the speculation is any less valuable than the spectualtion of teams like Bohl et al or Selsis et al. that is the kind of data-formualting that they do, and I see this chart as combining some of those possibilities with a broader data range than just Earth's Albedo and Venus' albedo. My original goal was to show that there are varied possibilities and to get acknowledgemnet that some of those combinations are indeed less likely, without doing anything that anyone else could not do with a known formula and know data. All the statements above here about speculation could be pointed at the papers used for referencing in the article, and the (all but raw) data itself, ie 20.3 years ago the planet "was" there and if not there anymore as of today most of the article is moot. With that statement I am only saying there is a limit to the speculation but cutting out all speculation would eliminate the article, so why stick to only the Venus albedo and Earth Albedo when there are other possibilities. I do recognize the need to qualify this, but it can be done in much the same way as the assumptions of coplaner orbits have been. As for any direct critique of the above table, I don't much care about sig difs, I only leave them there to show myself that they were calculated not measured, it is not written is stone, and it does not have to be my image. Just like the Sara Seager article I add quotes from and referenced, I prefer knowing the all the possibilities, however improbable for example a "gas dwarf" is for a 5 mass planet, I appreciate that a scientist was willing to publish that, in that way, rather than sticking to the tow-the-line perspectives. I don't at all mean to suggest something as outlandish as aliens could have terraformed it, but rather like Sarah Seager, you are right, we don't know, and that bit of honesty is again a fair addition I think. GabrielVelasquez (talk) 21:58, 19 October 2008 (UTC)
By looking at the formula you linked, there are at least three free parameters on which we have no data or only a range:
• albedo: no data
• radius: little data (we have minumum mass and we can estimate some reasonable range assuming compositions of the planet)
• emissivity: no data
So we need a three-dimensional object, not a chart, to describe the possibilities.
Moreover, if you feel that you can do reasonable assumptions to shrink those ranges, and you feel your work is as reasonable as the ones by Bohl et al. or Selsis et al., publish it on some peer-reviewed journal. This is the only way we can avoid OR concerns. --Cyclopia (talk) 23:14, 3 November 2008 (UTC)
You're going by your own definition, and contradicting yourself, and more over you are deliberatly being obtuse and difficult to try to frustrate me because you think you can get away with it after putting up that "request for comments on me." ...what it says above is "Known Formula" AND "Known Data," and the two dimensions you point out that are "not know" are what make up the chart as percentiles, as in 0.00 to 1.00, in step of however large you want to make the chart. What in effect you are saying is that Bohl et al. or Selsis et al and other teams can throw out any imaginary albedos and that's ok, but show the whole range from 0% to 100% and oh it's thought crime. The radius, for-god-sake, is speculated in almost every paper, and any one of them will do for a reference. Again, you can delete the almost whole article if you can't quote the speculation in the referencing. GabrielVelasquez (talk) 19:24, 7 November 2008 (UTC)

## Astronomy magazine Nov 2008

about 581c/d: "The inner planet is probably too hot for liquid water to exist on its surface and the outer one a bit too cold, although their temperatures would would depend on the nature of any atmosphere."

Hehe.... there's a nice reference for the "temperature debate". :)--Marhawkman (talk) 08:30, 28 October 2008 (UTC)

## Unconfirmed extrasolar "planet"

This "object" is not on the list of confirmed extrasolar planets, and this important fact should not be left out of the article, any "planet" article for that matter. There is confirmed and there is unconfirmed (candidate), and there shouldn't be any debate on this fact, so anyone messing with this edit should be considered to be vandalizing. 198.163.53.10 (talk) 18:26, 19 December 2008 (UTC)

According to who? Looking back at the edits to the cited list, it looks like there's a prejudice against anything radial velocity as a detection method. What's going on here? AldaronT/C 05:15, 6 July 2009 (UTC)
It's fairly well confirmed actually: the planet is still detected in a much larger dataset than the one available when the discovery was announced (with minimal adjustments to the parameters between the two fits), and its mass is dynamically constrained to lie in the planetary mass range. The Extrasolar Planets Encyclopaedia lists it in the main section, not the unconfirmed planets section. If anything the list of extrasolar planets article is at fault here, the entire system can be pretty safely moved into the confirmed section. Icalanise (talk) 19:45, 7 July 2009 (UTC)
I completely agree. Pleas contribute your views to the general discussion of this issue. AldaronT/C 20:35, 7 July 2009 (UTC)

## A large terrestrial planet?

Is this really a reasonable statement to have in the lede? The dynamically-determined upper limit on the mass means this planet could potentially be in the Neptune-mass regime. Furthermore there is no knowledge of whether this planet is terrestrial, an icy (ocean) planet, a small ice giant (Neptune-analogue), or something else. Icalanise (talk) 10:15, 29 October 2008 (UTC)

The general perception in the literature seems to be that it's a rocky planet. However, the aspect that it could be a gas dwarf is covered later in the article. If I understand it correctly, while this method can't get the upper limit of mass, if it was much larger the orbits would be different, wouldn't they? -- Logical Premise Ergo? 13:30, 29 October 2008 (UTC)
True the orbits would change as the inclination decreased, however the radial velocity curve would remain the same (because the orbital periods would remain the same). The radial velocity method gives you the orbital period, the velocity semi-amplitude, the eccentricity, the argument of periastron and the time of periastron. You have to calculate the semimajor axis from those and that depends on the true masses, and hence the inclination. In any case, if you read the Selsis et al. paper, they mention that accretion of significant gas envelopes can be a factor as low as ~6 Earth masses, only ~20% higher than the minimum mass for this planet (if you do the maths, you find there's a probability of about 45% that the mass exceeds 6 Earth masses, and roughly 15% that it exceeds 10 Earth masses, assuming random inclinations). Plus the other possibilities (e.g. volatile-rich planets, carbon planets) are mentioned in the paper, though admittedly these scenarios aren't thoroughly investigated. The point is that the planet's composition is totally unknown, so asserting that it is a terrestrial in the lede is probably misleading. Icalanise (talk) 15:43, 29 October 2008 (UTC)
I hate to be the one to do this to you all the time, but everywhere this planet is refered to as a "Super-Earth" and at that article is states in exactly the same way that this means a "large terrestial planet". Not disagreeing with you on your points, just pointing out that is the reasoning behind not calling it a "Super-venus" or any of the other possibilities. If you want to move the Sara Seager quote to the intro, I wouldn't complain, but keep in mind that the majority of references scientific and popular media refer to it as a "Super-Earth." though that's a term I myself dislike being used in this case. GabrielVelasquez (talk) 16:28, 29 October 2008 (UTC)
*laughs* This is why astronomy amateurs like me shouldn't ask questions. Took me a bit to follow all that. Would it be fair to say that the general scientific consensus is that it is likely / may be / is considered to be a terrestrial planet? I can read all the literature, of course, but since you've already done so, it seems redundant. -- Logical Premise Ergo? 16:40, 29 October 2008 (UTC)
I disagree that saying a planet is a "super-Earth" implies that it is a "large terrestrial planet". For example, this paper defines super-Earths in the first paragraph of the introduction to be planets "with masses between about 1 and 10 Earth masses". It then goes on to consider the possibility that some super-Earths would retain massive hydrogen atmospheres. According to this paper, "Super-Earths, includes ocean planets and massive terrestrial planets as a subclass in this mass range" (emphasis mine). Super-Earth appears therefore to be primarily a mass classification, sometimes with the caveat that a hydrogen atmosphere is not present, sometimes without this restriction. Making the equivalence between "super-Earth" and "large terrestrial planet" is not supported in the literature. Icalanise (talk) 16:43, 29 October 2008 (UTC)
I think the Super-earth article needs to be changed, then, since in the lead of that article, it basically describes a super earth as just that -- a large terrestrial planet. That would seem to suggest that all super-earths are telluric. -- Logical Premise Ergo? 17:21, 29 October 2008 (UTC)

## Removal of "(extremophile forms of)"

I initially removed all of the references to "(extremophile forms of)" for two main reasons. The first is that is was unnecessary repetition of the same thing. And the second reason is that it was inserted in a very ugly fashion. I am not suggesting that there should be no mention of it at all. Maybe it could be inserted in a better way that is not repetitive and a way that is more descriptive. Perhaps one or two sentences in the appropriate place would do the job? HumphreyW (talk) 00:40, 20 December 2008 (UTC)

"Ugly" is your opinion, there are enough uses in the encyclopea to leave it when it is necessary. "unecessary" is also your opinion, each use of the terms "habitable" and "habitability" are an issue, especially in this article but not exclusively. If you want to add the more correct phrase "Astobiological Potential" that also would be a whole other matter. I suspect you are one of those people who have not read the 214 page book that Stephen Dole and Issac Asimov wrote "Habitable planets for Man" which is about what type of planet people could live on and why, not extremophile survival as is refered to in the article. There is a difference and it is you ignorance on the subject that is "ugly." GabrielVelasquez (talk) 02:02, 24 December 2008 (UTC)
Yes, I still think it is very ugly, the repeated use of the bracket qualifiers makes it look very unprofessional (in my opinion). However I will leave to others to think about also. I don't wish to get into an edit war over it. I would prefer a different way to explain the extremophile thing.
I don't agree that the word "habitability" will automatically make people think about only human survival. I believe we should give people more credit and assume that they are aware that even Earth has many varied environments that life (not necessarily human life) can survive within. HumphreyW (talk) 02:35, 24 December 2008 (UTC)

I feel the same way about the repeated parenthetical qualification; it is redundant and ugly. I do agree that it is very important to thoroughly explain what "habitability" means in this context - mainly the possibility for water to be in the liquid state, if it happens to be present. Obviously it takes more than just liquid water for life to arise or even just survive, and far more is required for human life to be sustainable (without major life support systems). But this explanation and qualification of "habitable" should only be included once - repeating it over and over is just clutter. Sakkura (talk) 16:24, 13 March 2009 (UTC)

Ha, Ha, Ha - you want to mess with the scientist's quotes as well??!
http://en.wikipedia.org/wiki/Gliese_581_c#Future_observations
"Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extremophile forms of extraterrestrial life. On the treasure map of the universe, one would be tempted to mark this planet with an X.
205.200.19.57 (talk) 21:09, 3 April 2009 (UTC)
No. But there is no reason to repeat the qualification over and over. It's redundant. Sakkura (talk) 16:43, 7 April 2009 (UTC)

The discussion is moot as the section has been removed but the qualification will remain if the a brand new section (with current citations of scientists not journalists) is rewritten because there is no reason to confuse layman readers with the idea that the planet is habitable for people as has been hyped by some journalists, a sensationalism that likely started here with the quotes from the speculative discovery team of astronomer's (not astrobiologist's) hopes. GabrielVelasquez (talk) 07:43, 4 September 2009 (UTC)

## Communication from Gliese at SETI

I cannot find any source for this claim in section 5. Possible Contact.

"At approximately 20:45 UTC on 17 March 2009 faint radio signals were detected by SETI, coming from the direction of the Gliese 581 system. Although no language as we know it is present, the transmission features complex patterns of noise."

98.247.91.216 (talk) 23:10, 18 March 2009 (UTC)

http://thedianerehmshow.org/audio-player?nid=13421 at 24 minutes they let callers in, the first person claims to be a scientist who made contact... — Preceding unsigned comment added by 129.33.49.251 (talk) 15:09, 9 August 2011 (UTC)

## Companion E

Isn't the newly discovered 'Gliese 581 e' placing the whole planetary system more to scale?

I think the image of the habitable zone is as of today outdated. What about it? 83.136.195.130 (talk) 13:02, 23 April 2009 (UTC)

That is correct. There is a good one on Space.com here which would be a good replacement, or basis for creating a replacement depending on availability. Hiberniantears (talk) 14:43, 23 April 2009 (UTC)
Updated, from the original source with a CC image. AldaronT/C 15:36, 23 April 2009 (UTC)

## Discovery site: Switzerland?

The discovery site of this astronomical body was not Switzerland but the IV Region of Chile. The team who worked on the project included scientists from Switzerland but also from France and other countries.

A team of scientists from France, Switzerland and Portugal discovered the planets using the ESO 3.6-m telescope from the High Accuracy Radial Velocity Planet Searcher or HARPS, located at the European Southern Observatory (ESO) in La Silla, Chile.

Unless La Silla in the Atacama desert is an extraterritorial claim of ESO or of Switzerland? Moshe-paz (talk) 12:17, 2 July 2009 (UTC)

That's correct. According the the template definition, "discovery site" should be the observatory where it was discovered. I've changed the page to reflect that. AldaronT/C 18:14, 2 July 2009 (UTC)

## Lead paragraph

I'm gong to break this up for readability. Viriditas (talk) 22:24, 20 October 2009 (UTC)

## It is inside the habitable zone? Has liquid water?

I saw on here that it says the planet may lie outside the habitable zone, yet in this National Geography article it says it lies inside the Habitable zone and it has liquid water. http://news.nationalgeographic.com/news/2009/04/090421-most-earthlike-planet.html

i didnt look much into it, just thought i might share and see if you guys think we should change it. I dont know how to change it myself so if needed someone else should —Preceding unsigned comment added by 74.128.104.138 (talk) 18:53, 21 June 2010 (UTC)

This encyclopedia doesn't need people who don't read the article trying to change it to say what they want. Pitting National Geographic against multiple teams of astrophysicists who say it is out of the habitable zone is wasting peoples time and effort. National Geographic is regurgitating the same discovery team errors or you are reading wrong and the article is about 581 g not 581 c. "...it could have surface temperatures ranging from 700 K to 1000 K (430 to 730 °C)."
... Read the article! 24.78.166.69 (talk) 04:23, 30 September 2010 (UTC)
National Geographic is generally considered a reliable source as per WP:RS. The question seems to be about whether the theory put forward by that source is fringe as per WP:FRINGE. If that is the concern, then I would think that filing a request for outside opinion either through an RfC as per WP:RFC or asking for input on the possible "fringe" status of the opinion at WP:FTN would probably be the best ways to proceed. John Carter (talk) 17:47, 3 October 2010 (UTC)

## Artist's conception image should be removed

The artist's conception image should be removed or at least taken out of the planet's infobox and placed as "decoration" in the text of the article. There's nothing encyclopedic (and a lot that's misleading or just fanciful) about this (and most "impression") images. AldaronT/C 23:04, 6 October 2010 (UTC)

## Smallest planet?

The article claims that COROT-7b is the smallest confirmed extrasolar planet. The article at COROT-7b says it was the smallest until the discovery of Kepler-10b (1.4 Earth radii) in 2011, but there is no mention of being the smallest in Kepler's article. Furthermore, other discovered planets like PSR B1257+12 A (discovered in 2005) are claimed to be of sizes much smaller than Earth--one-fifth the size of Pluto as claimed in this reference. Now more recently in a January 2012 article here it is claimed that the three smallest extra solar planets ever found (the smallest of which was roughly Mars-sized), had just been discovered. Can anyone shed light on these discrepancies? Possibly something to do with the definition of what a planet is? Zujua (talk) 01:28, 21 July 2012 (UTC)