Talk:Habitable zone/Archive 1

Missing artist's conception

This article used to have an artist's conception of a habitable zone. This figure was a galaxy with a green band indicating a distance from the galactic center where radiation was not too intense for life. I don't see why a discussion on why it was removed.24.0.144.165 (talk) 18:00, 3 February 2011 (UTC)

Agreed. Pardon my toothless lackstyle. I need that depiction to know the relative of distance and sun size. I had it archived once for this very reason, but one OS led to another...

Also, since I'm too lazy to hope that my comments will be given time of the day, it wouldnt kill to make sure theres a comment of smaller suns giving off large solar flares relative, and the extreme UV given off in that. Citation? Something on discovery channel. I don't got a good memory, or a compassion for grammar.

i c wt ur doin. Ask ye, what good is this article to the common man? none. It's just a bunch of babble and jittery numbers.

-RapidlyChangingAlias, 2011/02/14, 14:55 —Preceding unsigned comment added by 99.251.96.205 (talk) 19:55, 4 February 2011 (UTC)

Diagram wrong?

I believe that the y-axis on the digram of habitable zones associated with this article is actually showing the luminosity of stars relative to the Sun, not their masses. A main-sequence star with twice the Sun's mass has a luminosity approximately 10000 times that of the Sun, so its habitable zone would be centered at sqrt(10000)*(1AU) = 100 AU, not 1.5 AU as the diagram suggests. Conversely a star with twice the Sun's luminosity would have a habitable zone centered at about sqrt(2)*(1 AU) = 1.4 AU, as the diagram shows, if we interpret the y axis as luminosity, not mass. Am I missing something? —Preceding unsigned comment added by 130.113.174.152 (talk) 16:36, 28 February 2008 (UTC)

You are wrong. A main sequence star with twice the mass of the sun is nothing like 10,000 times as bright as the sun. Main sequence stellar luminosity is approximately proportional to the 3.5 power of the mass. Qemist (talk) 23:07, 28 July 2008 (UTC)

Comment on Diagram

I think that Habitable Zones are not exactly like it says on the diagram. I believe that since Mars is on the Cold fringe of a habitable zone ^{as per here}, I think that the zone must be updated to put Mars on that fringe. Sorry if I'm wrong.

68.40.189.45 (talk) 14:51, 22 February 2009 (UTC)

• Furthermore, it is my understanding that Venus lies within the habitable zone for the Sun and would be able to sustain water if its atmosphere were thinner. Aubri (talk) 18:51, 1 February 2010 (UTC)

Need to State Earth's Current and Long Term Habitable Zone

Earth's current habitable zone (HZ) is 0.95 astronomical units (AU) to 1.37 AU. Earth's long term HZ is 0.95 to 1.15 AU.

Also suggest adding NASA graphic of earth's HZ: [1] Joema 14:36, 22 December 2005 (UTC)

That's wrong. The Earth does not have a habitable zone in the sense this article discusses. The sun has a habitable zone. As the figures you give indicate it is not centered on the Earth's current orbit, contrary to what the article repeatedly states. Qemist (talk) 23:11, 28 July 2008 (UTC)

Yes, I think merging Circumstellar Habitable Zones with Habitable Zones would be a good idea. Good idea to add current terrestrial habitable zone limits too. The NASA graphic already shows current CHZ based on the criteria discussed in the new addition. -- Dr. L.R. Doyle

Habitable to Whom?

"In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for the creation of life."

Does this not depend on your definition of life? Who is to say that other forms of life could not exist in conditions that humans would consider extreme? Wouldn't it be more accurate to say that the habitable zone is a region of space where conditions are favorable for the creation of human life, or earth-like life? --70.82.50.67 18:03, 15 June 2006 (UTC)

"and iodine for the the thyroid gland" Do extra-terrestrial organisms have thyroid glands? Can someone cite this?

Absolutely. We already know there is life existing on areas of Earth which would earlier have been be considered outside the habitable zone for "life as we know it". In Evolving the Alien: The Science of Extraterrestrial Life, Ian Stewart and Jack Cohen make a convincing case that "Goldilocks zone" represents a dearth of imagination. Earth seems amazingly well suited to us because it's where we evolved. Daibhid C 23:21, 24 October 2006 (UTC)

galactic Habitable Zone?

I was looking at an article on the milky way and clicked a link for "Galactic Habitable Zone" that lead me here. However, there is less than 2 sentences total on it. Can an expert add some content please?RSido 17:46, 25 February 2007 (UTC)

Criticism or Opinion?

"However, while it is relatively certain that life on Earth would be able to adapt to an environment like Europa's, it's far less likely for life to have developed there in the first place, or for it to somehow move there and adapt afterwards without advanced technology..."

This seems awfully editorial in nature. Either that or it's in need of a citation.

Macmanui 22:19, 26 April 2007 (UTC)

Agreed. That sentece stuck out to me. Earth life would pretty much die instantaneously if those conditions were present on Earth. Jiminezwaldorf 09:34, 7 August 2007 (UTC)

HZ around M dwarfs

I don't know how widely this is accepted, but I noticed this sentence in the abstract of this paper:

http://arxiv.org/abs/astro-ph/0609799 Title: A Re-appraisal of the Habitability of Planets Around M Dwarf Stars

Observations of protoplanetary disks suggest that planet-building materials are common around M dwarfs, but N-body simulations differ in their estimations of the likelihood of potentially-habitable, wet planets residing within their habitable zones, which are only ~ 1/5 to 1/50 of the width of that for a G star.

I mention it to compare to the graphic in the HZ article. —The preceding unsigned comment was added by 66.113.30.2 (talk) 02:47, 27 April 2007 (UTC).

The habitable zone for M dwarfs maybe much further out than the graphic in the HZ article suggests because it is likely that any Earth like planets orbiting red dwarfs will have much higher concentrations of the strong greenhouse gas methane in their atmospheres. Ultraviolet light from our sun, a G-type star, breaks down methane rapidly, within 10-12 years whereas it takes over 200 years for a typical M-type star to do the same. A runaway build up of methane, on any Earth like planet oribiting a Red dwarf, is very likely.—Preceding unsigned comment added by 94.193.61.125 (talk) 10:17, 9 March 2010 (UTC)

No mention of width

It's not just one number, it's a habitable ZONE. So what determines the width of a HZ? The above comment discusses M stars only having a width of 1/5 to 1/50th. Can anyone help me?

210.23.136.200 02:04, 8 October 2007 (UTC) Tim

Conditions for existence of liquid water determines the width of the habitable zone. This is found by modelling the planet as a greybody and finding its equilibrium temperature. It involves: heating effects, due to irradiance from the parent star, in W/m² against the daylight side of the planet (area =π r²); and cooling from radiant emittance of the planet's whole surface (area =4π r²); related to temperature through the Stefan-Boltzmann constant; and compared to the range of temperatures for liquid water. If we do this calculation for Venus' orbit, we get an equilibrium temperature of 60°C. For Earth, it's 5.6°C, and for Mars it's -47°C. These values may differ from actuals due to color temperature of the parent star, atmospheric composition, rotation, greenhouse effect, albedo, and heat flow. -- 99.233.186.4 (talk) 00:29, 13 January 2010 (UTC)

Criticism

"However, while it is relatively certain that life on Earth would be able to adapt to an environment like Europa's, IT'S FAR LESS LIKELY for life to have developed there in the first place"

Why is it so far less likely? Can someone show me just one proof?

The guy in the above line makes a good point. We have not yet seen life develop anywhere but earth, and so should be slow to rule out possibilities without evidence.

"A planet that used to be in the habitable zone is more likely to have life than one that has moved into it."

And again - why so?

132.177.70.205 16:17, 29 April 2007 (UTC)Ramond

Estimates of likelihood should perhaps be given in terms of speed. Life will probably evolve anywhere that conditions favour it, thermodynamically. For earth-like life, you need: liquid water, essential elements, and an energy source and sink. Europa, or any planet that moves into a habitable zone, could possibly develop life given enough time. If meteorite from Mars can land on Earth, then water bears could find their way to anywhere in our solar system. -- 99.233.186.4 (talk) 02:53, 14 January 2010 (UTC)

Galactic habitable zone: Huh?

"Heavier elements must be present, since they form complex molecules of life, such as iron as the foundation for hemoglobin and iodine for the thyroid gland."

What do hemoglobin and thyroid glands have to do with the basic requirements for life? Carbon, Hydrogen, Nitrogen, Phosphorous and maybe a couple of others you can probably make a strong case for, but archaea do fine without hemoglobin. The plant world does fine with magnesium-based chlorophyll. Heavier elements are needed to form rocky planets, but not, as far as I can tell, for life itself. Life is opportunistic. If incorporating heavy elements that happen to be available makes things work better, it's liable to happen, but we're interested here in requirements common to all life as we know it.

I agree, the reference to thyroid glands is out of place in this article. Perhaps that sentence could be rewritten to retain a reference to the importance of metals to life; I don't know enough about biology to do it properly, but I'll probably try to clean it up a bit if no one better qualified does it in a reasonable amount of time. Deerslayer (talk) 21:27, 2 March 2008 (UTC)

Yes, it is out of place, however, I think that whoever wrote that meant to allude to something that is essential to human life. Carbon-based life is life as we know it, and I'm thinking that maybe whoever it was that put the thing about hemoglobin meant that animal-like creatures would not develop without those elements. But also, heavy elements are needed to form terrestrial planets, as compared to gas giants. And, because gas giants are not likely to form carbon-based life, while terrestrial planets are more likely to, heavy elements are needed for the development of carbon-based life. WingedSkiCap (talk) 00:09, 5 December 2008 (UTC)

"On the other hand, the solar system must be far enough from the galaxy center to avoid hazards such as impacts from comets and asteroids ..."

This is the real "Huh??". Is the suggestion that a passing interstellar asteroid from the galactic core is likely to hit a solar system? What would that mean? Asteroids and comets come from within a solar system. Comet impacts played an important role in providing water to the early earth. Asteroid impacts are not necessarily a hazard either. I've seen it claimed that they have played a vital role in evolution. Perhaps the idea is that a planet in a system nearer the core would be subject to too many asteroid and comet impacts, but if so, that should be spelled out. -Dmh 16:07, 10 May 2007 (UTC)

If I recall correctly, the argument is that a greater number of nearby stars will increase the chance of a comet's orbit changing from a star's oort cloud to a more elliptical one. I'll see if I can't find a source for that. Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 23:23, 6 September 2007 (UTC)

The idea is that the higher metallicity near the galactic core results in the formation of more and larger asteroids and comets. I believe that the concern regarding the danger to life is valid - think of the devastating effect of the asteroid that struck Earth 65 million years ago. Deerslayer (talk) 20:26, 2 March 2008 (UTC)

I have recently made an edit to the page. I hope that clears things up. The galactic habitable zone really has nothing to do with asteroids and comets; it's the radiation that's deadly. WingedSkiCap (talk) 07:49, 22 December 2008 (UTC)

Removed editorial comment

Someone inserted the following comment into the page:

<<the previous statement is imprecise. please edit this contribution: it would be better to describe a star as "developing".

To begin with, it is heated by gravitational energy as its gas cloud contracts. It ignites certain nuclear fusion reactions between protons (hydrogen nuclei) and the nuclei of the next heavier elements, lithium, beryllium, and so on. This "getting hotter" period doesn't take any very large part of the life of a medium-sized star. For most of its life, the star then stays pretty steady in its output, burning hydrogen into helium. When enough of the hydrogen is used up, the star shrinks, and then gets hot enough to become violent. Possible end-products are a white dwarf, a red giant, a neutron star, or a Black Hole, AJR>>

Most of this is superfluous information about stellar evolution, so I removed it. I rejected the suggestion to describe the star as 'developing', because the term 'evolve' is well-understood and accepted in this context. I did remove the part from the earlier version about the star 'getting hotter', because there are obvious counterexamples (eg, evolution into a red giant), and because it's irrelevant to the point here - the position of the CHZ doesn't depend on how hot the star is, only on its luminosity. --130.155.198.32 (talk) 04:21, 14 January 2008 (UTC)

'likeliest candidates to be habitable and thus capable of bearing extraterrestrial life similar to our own'

Whoever put this line in makes it look like were assuming a lot. 'similar to our own'Protoform (talk) 08:37, 13 April 2008 (UTC)

Vauge Intro, Vauge Article

"In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for life as it may be found on Earth." - most things on Earth would die in space so this "region" business has to be clarified, and as far as "conditions" are concerned, the zone is a region of space that is affected by one condition (that influences life directly and continuously), and that is the distance from the sun. The whole concept seems to be mono-dimensional and is being heavily misinterpreted and misused to suggest a lot of other factors that may or may not be there. Venus is supposedly in the habitable zone, but is not habitable. Likewise Mars, in the zone but not itself habitable. Titan may harbour life but it is nowhere near the habitable zone. This is a concept that is itself flawed and needs heavy clarification. I suggest this other article to anyone who whats to begin to understand how many dimensions ("conditions") really need to be met: Climate Modeling.
If I can find the time to compile the information I will try to improve this article myself. GabrielVelasquez (talk) 20:29, 10 July 2008 (UTC)

What they mean by this is that the habitable zone would be the most likely region in which life can form because electromagnetic radiation allows the existence of liquid water. It is true that liquid water exists on other celestial bodies not in the habitable zone, but in this case, the article is about the habitable zone, which is derived from electromagnetic radiation. That means that the STAR is the variable we are using, and the planet or other celestial body does not factor in. Cases like Europa, Encladus, and Titan are "special cases", as one might call them. To answer your questions about Venus and Mars, the habitable zone in this case is, once more, about the STAR, not the PLANET. The planetary conditions are an entirely different subject, although they should be at least referred to or linked to on this page. I might put up a part on this article later explaining planetary conditions. WingedSkiCap (talk) 00:22, 5 December 2008 (UTC)

Gliese 581d

The article claims that Gliese 581d is the best example which has been found so far of an extrasolar planet which orbits in the theoretical habitable zone of space surrounding its star. Cursory calculation shows that it is nowhere near the habitable zone specified by the article (0.95 to 1.37ua) after rescaling by sqrt(L(Gl581)/L(Sun)) (approx 0.114). There are many exoplanets known to orbit deep within the habitable zone (HD 20367b). Why the special mention of Gliese 581d? I say remove it. Qemist (talk) 00:21, 29 July 2008 (UTC)

The planet HD_108874_b has been very mich downplayed when it has nearly the same insolation as the Earth. GabrielVelasquez (talk) 20:33, 14 September 2008 (UTC)

Since the claim that Gliese 581d is in the habitable zone is perfectly referenced in its article, but the values given here aren't, I doubt that they are correct (at least at the current state of knowledge). Can someone provide references for them?--Roentgenium111 (talk) 17:40, 23 April 2009 (UTC)

Heavy elements - Galactic Habitable zone edit justification

I'm editing the heavy element paragraph under galactic habitable zone for the following reason: There is currently a jarring parenthetical which states: "(assuming iron is necessary for all life)". This is an unnecessary parenthetical as the inclusion of iron with the words "such as" indicate that it is an example of heavy element requirements in a some life forms. Hemoglobin itself is not necessary for life (witness the horseshoe crab). The website (http://gsa.confex.com/gsa/2005ESP/finalprogram/abstract_88538.htm) mentions that iron is but one potential source of energy for single-cell life forms.

I'm editing out the parenthetical. I'll do so in such a way that reads better than my previous edit, but would prefer this new edit not be reverted. If you don't like the edit, please change it to something else, don't just revert it to the current crufty (and inaccurate) phrasing. --99.14.107.65 (talk) 14:09, 16 November 2008 (UTC)

Edit Justifications

This is the section in this article to justify major edits.

I edited almost every section of this page, and added a new section. There seemed to be many times in the article when someone wrote in a tone that indicates uncertainty and which looks unprofessional. Also, there were, as seen on this talk page, several misunderstandings about the habitable zone. I think my edits cleared them up, though. This is the URL of the original document versus the edited version: http://en.wikipedia.org/w/index.php?title=Habitable_zone&curid=1072751&diff=259483528&oldid=259074661

Also, there were several places in the article where the author of that section put in invalid information. I corrected these (but if I did them wrong, please make them better!!

Besides this, the article could still use improvement. I'm thinking about taking the whole section on criticism out, because it is irrelevant and does not really enhance the article. Also, the part about Gliese 581 D, as someone has already pointed out, probably should be taken out, and also a better introduction needs to be written. I might do this if I have time, but chances are I won't.

WingedSkiCap (talk) 07:40, 22 December 2008 (UTC)

Juxtaposed

From the article header: "and these two factors are not meant to be juxtaposed.". Does this sentence make any sense and is this use of "juxtaposed" correct given the context? ---- —Preceding unsigned comment added by 85.159.97.3 (talk) 12:48, 29 April 2009 (UTC)

Confusing sentence in introduction

The article currently starts as:

The habitable zone (HZ) in astronomy is a region of space where stellar conditions are favorable for life as it is found on Earth. The habitable zone is the intersection of two regions that must both be favorable to life; one within a planetary system, and the other within a galaxy.

I emphasized "stellar conditions" here because I don't grasp fully what it wants to say: the habitable zone does not depend only on the star type/evolution phase, but on the distance from it, etc. Either I would remove "stellar conditions" or I would further explain, something like "where conditions allow an astronomical object to sustain Earth-like life". There is a sourced definition here declaring it simply as "the region around a star where an Earth-like planet can maintain liquid water on its surface", but I am unsure about it. I am asking because maybe "stellar conditions" has some meaning/source I am unaware of, in which case I think it should be better explained. --Cyclopia (talk) 06:46, 10 September 2009 (UTC)

I agree that "stellar conditions" is confusing. Lunar conditions are conditions on the moon, martian conditions are conditions on Mars, so the reasonable interpretation of "stellar conditions" is conditions on a star. It isn't conditions on the star per se that define habitability but those on the planet ("object"). Those are partly determined by the star it is orbiting, but only in conjuction with other factors (such as how far away the planet is from the star, and galactic factors unrelated to the star). Qemist (talk) 06:45, 13 September 2009 (UTC)

I now used the sourced definition from the VPL. Not completely satisfactory in my opinion but it is sourced and better than "stellar conditions" I'd say. --Cyclopia (talk) 08:35, 13 September 2009 (UTC)

Formulas for calculating the extent of habitable zone

Hi.

I found this:

The distance from a star where this can take place is assumed to be centered where the star's brightness is equal to that of the Sun at 1 AU. It can be calculated from star size and luminosity. The CHZ of a particular star is "centered" on a distance determined by the equation:

$d_{AU}={\sqrt {L_{star}/L_{sun}}}$

where

$d_{AU}\,$ is the mean radius of the HZ in astronomical units,

$L_{star}\,$ is the bolometric luminosity of the star, and

$L_{sun}\,$ is the bolometric luminosity of the Sun.

The inner and outer edges of the zone are assumed to be at 95% and 137% of this distance, respectively.

While entirely reasonable, it is unsourced and smells a bit like OR and/or synthesis -especially no reason is given for the edges. I'd be more than happy to put it back if sourced. I removed it just for the sake of caution and discussion. Thanks! --Cyclopia (talk) 22:09, 26 September 2009 (UTC)

Kasting's reference

The 0.95 AU distance for the inner edge of the habitable zone stated in the article's table was actually Kasting's maximum distance for the inner edge. In other words, he calculated that the inner edge was at most 0.95 AU from the sun, and that it probably actually closer - although exactly how close the inner edge could be was hard to pin down. —Preceding unsigned comment added by 128.227.185.221 (talk) 19:43, 11 December 2009 (UTC)

Merge content from Goldilocks planet and Goldilocks Principle

because, in my opinion, these are just popular nick-names for the Habitable zone or planets in it. --John Maynard Friedman (talk) 12:45, 17 December 2009 (UTC)

• I support this merger.--John Maynard Friedman (talk) 12:45, 17 December 2009 (UTC)

• I support merging the content of Goldilocks planet into Habitable zone and/or Planetary habitability as appropriate, but not Goldilocks Principle or Rare Earth hypothesis. Even if we don't merge, I think the "Goldilocks planet" article should be renamed "Habitable planet", as I think a title based on scientific terminology is preferable to one based on a children's fairy tale. WolfmanSF (talk) 10:09, 11 October 2010 (UTC)

What about merging this with Rare Earth Hypothesis which seems to discuss a similar phenomenon, even including some of the same illustrations. http://en.wikipedia.org/wiki/Rare_Earth_hypothesis Or, perhaps merging all 4 articles?--Keelec (talk) 09:01, 14 January 2010 (UTC)

• Oppose merging Goldilocks Principle, as this is in fact more general than just in astronomy. It can be used in relation to any rise of complexity (which includes various phenomena of human history). --JorisvS (talk) 18:37, 15 January 2010 (UTC)

• Oppose this merging. Both articles are distinguishable in their own respect and deserve to be kept as such. KirtZJ (talk) 22:18, 12 December 2010 (UTC)

• Oppose merging either Goldilocks Planet or Goldilocks Principle into Habitable Zone. Goldilocks Planet might be best merged into Planetary Habitability, based on the strength of this portion of the current introduction to Habitable Zone: The habitable zone is not to be confused with the planetary habitability. While planetary habitability deals solely with the planetary conditions required to maintain carbon-based life, the habitable zone deals with the stellar conditions required to maintain carbon-based life, and these two factors are not meant to be interchanged. Petershank (talk) 19:42, 13 December 2010 (UTC)

Merge from "Goldilocks planet" implemented. -- Beland (talk) 17:55, 6 February 2011 (UTC)

Thanks, good work. Polyamorph (talk) 09:20, 7 February 2011 (UTC)

Just an observation, the vote for Merger was 3 against 2 for. Interesting Magnum Serpentine (talk) 02:43, 13 June 2013 (UTC)

Hydrostatic Equilibrium

I just thought that it was wierd that nobody talked about how any habitable planet, in order to have an atmosphere, has to be in hydrostatic equilibrium. Basically, it has to be big enough, and it is not like we could colonize an asteroid and terraform it.

P.S. Besides, this is a very important factor in colonization of planets.

Miniwikiuser (talk) 04:07, 12 January 2010 (UTC)

The current definition of planet requires that they be in hydrostatic equilibrium, so it cannot be a requirement for planetary habitability. I suggest you leave scifi/fantasy topics such as the colonization of other planets out of this article. Qemist (talk) 14:13, 12 January 2010 (UTC)

I agree with Qemist. Besides, the argument is flawed because transformation of an asteroid into a habitable space station is not-only possible, it's probably a good idea, yielding access to tonnes of raw materials including propellant, that you don't have to lift from Earth's surface. [2][3][4]. perhaps it's time for an article on asteroid settlement? -- 99.233.186.4 (talk) 23:02, 12 January 2010 (UTC)

the two should not be merged - just cross-referenced - many people will search under only one of the two terms —Preceding unsigned comment added by 108.18.243.16 (talk) 14:01, 31 October 2010 (UTC)

Habitable does not equal habitable by humans ! It means habitable for life. See Space Colonization instead !--EvenGreenerFish (talk) 00:56, 5 February 2012 (UTC)

category:extrasolar planets within habitable zone?

Why can't i find a list of exoplanets that are within their stellar habitable zone? There should be a category -- 99.233.186.4 (talk) 09:59, 10 February 2010 (UTC)

Because none have been found yet (at least, not confirmed). There are a couple of possibles, but no definites. Modest Genius ^talk 01:42, 10 February 2011 (UTC)

Well, there are no confirmed Earth-sized exoplanets in the HZ. But there are quite a few giant planets known. Kevin Nelson (talk) 07:14, 24 November 2011 (UTC)

Try Category:Extrasolar planets in the habitable zone --EvenGreenerFish (talk) 05:41, 6 September 2012 (UTC)

Examples and Bias

Gliese 876 is a system that is not mentioned at all in the examples. It has two planets within the habitable zone and is within 15 light years. However there is clear bias in this section toward planets which are believed to be terrestrial. The flaw in this logic is that we know just as little about the planets in these systems as we do the likeliness of habitable moons and even co-orbitals. I suggest the list gets scratched in favour of a proper objective discussion of habitability of astronomical objects. --EvenGreenerFish (talk) 13:56, 5 July 2011 (UTC)

I don't think this is an intentional bias, moreover it is (like most wikipedia articles) simply incomplete. Any attempt to making this a more complete and balanced article would be welcomed. regards Polyamorph (talk) 17:36, 5 July 2011 (UTC)

Plot of change in HZ over time

Just a suggestion: the article could use a plot of the change in the habitable zone over time (as the host star increases in luminosity). Thanks. Regards, RJH (talk) 22:37, 12 August 2011 (UTC)

Structure problems ie Duplicated "Potential Examples" sections ...

There appear to be two "Potential Examples" sections, one at the top level and another inside CHZ. They both say more or less exactly the same thing. Additionally, the criticisms at the top level appears to be related to both CHZ and GHZ, yet is does not differentiate between the two. Also, its really not clear as to whether a Goldilocks planet must be located within both the CHZ and GHZ. I understand that it is assumed, because that is our planet finding region, however it needs to be more clear. --EvenGreenerFish (talk) 01:10, 18 November 2011 (UTC)

Life can only exist on terrestrial planets ... this is bollocks

Additionally, I have a real issue with this unsourced paragraph: "To harbor life, a system must be close enough to the galactic center that a sufficiently high level of heavy elements exist to favor the formation of rocky, or terrestrial, planets, which are needed to support life". This is clearly a a very narrow Point Of View and does not concur with current studies in astrobiology. To assume that life must require a terrestrial planet is an extremely strict criteria. Personally I would imagine that life could be found on low density liquid or even gaseous celestial bodies with organic materials and some sort of energy source. Additionally this definition excludes environments such as dwarf planets and natural satellites with habitable environments such as subsurface oceans. --EvenGreenerFish (talk) 01:14, 18 November 2011 (UTC)

Agreed. That's a very anthropocentric POV. Why must "life" even remotely resemble us? Carl Sagan proposed a whole series of lifeforms that might live in the atmosphere of Jupiter or Saturn (don't recall which :( ), & there is no reason to believe Nature can't come up with better than we can imagine (to crib Arthur Clarke...) For all we know, the spacefaring "whales" Chris Claremont & Dave Cockrum postulated in X-Men could exist... TREKphiler ^{any time you're ready, Uhura} 01:26, 18 November 2011 (UTC)

"bearing extraterrestrial life similar to our own"

I'm not comfortable with this definition in the introduction as it is a very clear example of carbon chauvinism and far too Earth-Centric. What exactly is the definition of "similar to our own" ? And what really is its significance to the subject ? What it comes across as generally assuming fauna and flora. However Life on Earth is more varied, we find Prokaryotic and Eukaryotic organisms existing side by side with plants and animals, microbial life and extremophiles living deep within the planet's crust and high in the atmosphere, so what exactly does "similar to our own" mean ? Is the aim of defining habitable zone for finding life or finding life that is similar to our own ? In terms of astrobiology, it is possible that microbial life that is "similar to our own" could be found outside of the habitable zone. It also follows that life with different ingredients could be very different to what we find here regardless of whether it is found in the habitable zone or not, we may also find the most common life in the habitable zone is not similar to our own. So what is the significance of this statement ? --EvenGreenerFish (talk) 01:50, 18 November 2011 (UTC)

I would say that life "similar to our own" means life that relies on liquid water. I agree that the article should not assume all life must be of that sort. But life of that sort has been the main focus of scientific discussion, mainly because it is not very clear how to best go about searching for other kinds of life. So I think it is reasonable that such life should also be the main focus of the article. Kevin Nelson (talk) 07:05, 24 November 2011 (UTC)

There's a strong bias in the science to finding life resembling Earth's. (Probably since we have no frame of reference for life unlike it...) Even the presumption it need be carbon-based isn't a given, tho as I understand it, a very high probability (it appears to be easiest to combine into biologically useful forms). The definition of "like ours" needs clarification IMO: like Man? Or like terrestrial Earth? TREKphiler ^{any time you're ready, Uhura} 18:23, 24 November 2011 (UTC)

There are a number of chemical reasons scientists (including Astrobiologists) look for "life as we know it". It's not "like man", it's "like on Earth". If you look at theoretical life forming under a different chemical system than the one we formed under, there always seems to be a hitch. Not necessarily an insurmountable one, but one that makes the other system less ideal. Turns out that if, for example, you consider life originating around a liquid methane system rather than water, the reaction rates are so slow that estimates on life taking hold in such an environ are ~20 billion years (and that's a very conservative number). That drastically limits where a habitable planet based on a methane system would be (Possibly only around a red dwarf). George Wald (1964) (I recall the year but not the title) outlines some other compelling chemical reasons that are still valid today. There is also the issue of using the "terrestrial analog" approach to life searches because we do not have a good definition of what life is. Can methane based lifeforms exists? In theory, yes. Can water based lifeforms exist? In FACT, yes. Since we know water based life forms can exists, we go for what we know when we search. SETI is another example of limiting the search to what we know. In their case, the search method allows for all kinds of life form bases. However, it requires that those lifeforms have evolved sufficiently to use radio and have in fact taken a path to do so. Obviously that is not all encompassing of life - which is why they are being clear(ish) when they use the term "intelligent" When scientists say, "life as we know it" or similar, they are not being biased, they are being clear on how they are limiting the investigation.

Habitable Zones and CHZ like the one in this article are tools used in searching for and trying to understand life outside our planet, and are based upon life as we currently understand it. Can other life form types exist outside our habitable zone? Certainly. In fact, life as we know it can exist outside the CHZ. Look at Europa. Mars is outside the CHZ, and yet, life could very well have started there and even be there now in some very limited environs. The HZ and CHZ come from a time when we thought life required water AND sunlight. We know now that it is very possible life on earth originated in the absence of sunlight - that energy is all that is required and things like hydrothermal systems could provide that.

If the article says life cannot exist outside the habitable zone, it's wrong - or at least unsupported. If the article says all life must be like ours, it's wrong as well. But I didn't see that it says either. Prospero66 (talk) 12:32, 5 February 2012 (UTC)

Also, I don't think "Habitable zones are used in the Search for Extra-Terrestrial Intelligence and is based on the assumption that should intelligent life exists elsewhere in the Universe, that it would most likely be found there." is trueProspero66 (talk) 12:47, 5 February 2012 (UTC)

Heavy Metals a prerequisite for life ????? Ahh, yeah ok ....

There is a whole paragraph in the Galactic Habitable Zone section dedicated to the premise that heavy metals are a requirement for life to exist. It appears to be heavy POV and highly likely someone's own research. The only source used is an incredibly vague geology article which is rhetorical rather than anything conclusive. I've found nothing else that strongly support this. Yes, humans require heavy metals in relatively small amounts like iron and zinc. However it seems ridiculously anthropocentric to extend this to all lifeforms. The building blocks of life (DNA and cell biology) are all relatively light elements - nitrogen, hydrogen, oxygen, carbon, phosphorous. In fact most heavy metals are toxic to life - lead, mercury etc. --EvenGreenerFish (talk) 08:26, 24 November 2011 (UTC)

As said above, frame of reference plays a part. There's a usual presumption for life to need terrestrial planets, but that's not a given... AFAIK, tho, there's very little study of the possibilities of life on gas giants or non-terrestrial planets. TREKphiler ^{any time you're ready, Uhura} 18:23, 24 November 2011 (UTC)

I don't know of anything that says life as we understand it requires anything more than CHONPS+energy (oh - and carbon cycling and tectonics) — Preceding unsigned comment added by Prospero66 (talk • contribs) 12:35, 5 February 2012 (UTC)

Meaning of acronym "CHZ"

According to the article right now, "CHZ" means "circumstellar habitable zone." But in every source I have looked at, it stands for "continuously habitable zone." These are two quite different things. Can anyone find a source where the acronym is used in the former sense? If not, the acronym should be changed. Kevin Nelson (talk) 08:47, 24 November 2011 (UTC)

Now the article contains no definition of CHZ, which seems worse than either of the previously mentioned possibilities. — Preceding unsigned comment added by 66.31.201.205 (talk) 04:18, 12 January 2012 (UTC)

It means continuously habitable zone in every book or article I have read. The Habitable zone and the CHZ are both "circumstellar". I would just define the acronym in the article as continuously habitable zone since that is basically the main stream usage. that's just me though 70.173.128.75 (talk) 01:40, 10 February 2012 (UTC)

About half of the "*HZ" references are to CHZ and half to GHZ. This is quite confusing, since (as noted above) there is no definition of CHZ given in the article (and only an implied definition of GHZ by being within a few sentences of the bold phrase "Galactic habitable zone"). Someone who knows about this stuff, please clarify in the article. - dcljr (talk) 23:10, 5 March 2012 (UTC)

Various definitions of habitable zone from various reputable sources

Below I list 9 definitions of the HZ I have found in various reputable sources. The first 5 come from primary sources in the research literature, while the last 4 are from review articles and books that should count as reputable secondary sources. Notice the following important points: 1) All of the definitions are strictly in terms of regions around a star--none of them bring in the galactic habitable zone or anything like that. 2) None of them use the phrase "circumstellar habitable zone"--they all appear to use just "habitable zone" for what the article currently calls "circumstellar habitable zone." 3) The consistent common factor is that in the habitable zone, liquid water can exist on a planetary surface. I'm not sure if I want to put any of the below definitions into the article verbatim, but I think I would like to rewrite the lead to more closely reflect the consensus among them.

Borucki, Koch, Basri et.al. "Characteristics of planetary candidates observed by Kepler II..." Astrophys.J. July 2011 "The HZ is often defined to be that region around a star where a rocky planet with an Earth-like atmosphere could have a surface temperature between the freezing point and boiling point of water, or analogously the region receiving roughly the same insolation as the Earth from the Sun (Kasting et al. 1993; Rampino & Caldeira 1994; Heath et al. 1999; Joshi 2003; Tarter et al. 2007)." (Sec. 3.2, pp.9--10)

Guo, Zhang et. al. "Habitable zones and UV-habitable zones around host stars" Astron.&Astroph. 2011 "Typically, stellar habitable zone (HZ) is defined as a region near the host star where water at the surface of a terrestrial planet is in liquid phase." (p.1)

Jones, Barrie; Sleep, Nick; and Underwood, David R. "Habitability of known exoplanetary systems based on measured stellar properties" Astrophys.J. 649:1010-1019, Oct. 2006 "The classical HZ is that range of distances from a star where water at the surface of an Earth-like planet would be in the liquid phase." (p.1010)

Tarter, Backus, Mancinelli et.al. "A reappraisal of the habitability of planets around M dwarf stars," Astrobiology 7(1), 2007 "There are a number of different definitions of the HZ (e.g., Dole, 1964; Heath et al., 1999), but here we define it as that region around a star in which a planet with an atmosphere can sustain liquid water on the surface." (p.35)

Traub, "Terrestrial, Habitable-zone exoplanet frequency from Kepler" Astropys.J. (accepted preprint) 2011: "There is general agreement that the HZ is defined as the planet-star distance range within which liquid water can exist on a planet's surface." (Sec. 10)

Lammer, Bredhoft, Coustenis et.al. "What makes a planet habitable?" Astron Astrophys Rev. 17:181--249, 2009 "Earth orbits its host star---the Sun---within a region that is called the habitable zone (HZ)---the region where an Earth analog planet can maintain liquid water on its surface." (p.183)

Perryman, _The Exoplanet Handbook_ (2011) "The _habitable zone_ is loosely defined by the range of distances from a star where liquid water can exist on the planet's surface." (p.283)

Seager, _Exoplanet Atmospheres_ (2010) "The habitable zone is the region around a star in which a planet may maintain liquid water on its surface." (p.6)

Kasting, _How to Find a Habitable Planet_ (2010) "Harlow Shapley defined the `liquid-water belt' as the region around a star in which a planet can maintain liquid water on its surface....[Su-Shu Huang's] most lasting contribution may have been his definition of the term _habitable zone_ as another synonym for `ecosphere' and `liquid-water belt.' " (pp. 171--172)

Kevin Nelson (talk) 02:27, 30 November 2011 (UTC)

Appreciate what you've tried to do Kevin, using established definitions is a logical approach (you should also probably quote them as references). The issue as I see it is that this approach does not solve the dilemma of the article - that is, that the lines between Planetary Habitability and the Habitable Zone are too blurred and the intro have become fuzzier again. Lammer, Bredhoft, Coustenis and Borucki, Koch, Basri et.al. are essays on planetary habitability and thus should be associated with that article. The other issue is that this is a rapidly evolving field, the GHZ is a relatively novel concept. One hand we're talking about conditions in which water can exist and the next we're making assumptions based on terrestrial planets in reference to Earth-like conditions. The majority of definitions you've quoted only refer to "planet" but are not as narrow to talk about specific Earth-like properties (such as atmosphere and composition) when we cannot predict these things accurately. Additionally we now know that moons and other celestial objects may fit the planetary criteria. Using your frame of reference, perhaps it needs to be more clear at the very outset that we are referring to a very specific criteria for planetary habitability. How is the nature of the zone redundant ?? These definitions are just as important as the speculations now made and to assumes that groundwater cannot exist or support life is clearly false. --EvenGreenerFish (talk) 07:37, 2 December 2011 (UTC)

"I would like to rewrite the lead to more closely reflect the consensus among them" I would advise including at least some mention of the inherent bias in the common view. Notice all presume the need for liquid water, which strongly implies life like that on Earth. While this means "habitable for Man" (or "for Earthlike creatures"), that is by no means the same as "habitable". Nor should we say it is. TREKphiler ^{any time you're ready, Uhura} 08:28, 2 December 2011 (UTC)

FWIW - At the moment, I tend to agree w/ those who think the current HZ definition in the lede may be defined too narrowly - after all, there are known life forms requiring little or *no water* whatsover (esp Xerophiles such as Tardigrades) (My NYT Ref) - as well as - known life forms requiring little or *no oxygen* whatsoever (esp Anaerobes such as Spinoloricus nov. sp.) - there are other known "extreme" life forms - Interestingly, recent studies seem to suggest that the complex chemical starting materials for life forms may be found in cosmic dust and may be created naturally, and rapidly, by stars (Nature Ref & Wikilink Ref) - as a consequence, starting materials for life may be distributed *nearly everywhere* in the known universe - a *much broader HZ definition* in the lede may well be in order I would think - in any case - enjoy! :) Drbogdan (talk) 11:04, 2 December 2011 (UTC)

•whew•! If that's just for terrestrial life forms, you can bet there are cases even weirder on planets we haven't explored. TREKphiler ^{any time you're ready, Uhura} 01:51, 3 December 2011 (UTC)

Yes - seems life on other planets may develop in some (very?) interesting ways - Several quotes from a relevant NYT article (12/02/2011) (perhaps helpful in finding a better/broader definition of HZ?):

• "[There is] only one ironclad requirement for life, besides energy: a place warm enough for chemical reactions to go on," according to NASA chemists.
• "Animals are overgrown microbes. We are here to ferry microbes across the planet. Plants and animals are an afterthought of microbes," according to Dr. Paul Falkowski, biophysicist. So, we are likely to find that "our neighbors [on other planets] are microbes. After all, on Earth, microbes were the whole story for almost four billion years and now inhabit our intestines as well as every doorknob," according to the NYT. Besides, "99 percent of the genes in our bodies belong to microbes inhabiting us and without which we could not live," according to Dr. Dimitar Sasselov, astrobiologist.
• "Even Earth, wonderful and special as it is, will only have animal life for one billion years," according to Dr. Donald Brownlee, astronomer.

In any regards - Enjoy! :) Drbogdan (talk) 21:50, 3 December 2011 (UTC)

"Hypothetical planet types" ???

This article is in the category "Hypothetical planet types." It's not a type of planet, and there's no reason why it should be in there. I can understand habitable planet being in there, but not habitable zone. Let's take this page out of that category. Samcashion (talk) 05:36, 6 December 2011 (UTC)

You're probably right. Looking at the current cats, it looks like someone went a bit wild adding non-essential cats. I'll take a closer look. Viriditas (talk) 05:57, 6 December 2011 (UTC)

Basic assumptions

The second most basic assumption in calculating a C-SHZ, after determining current stellar output, is to determine the variability of stellar output over various periods. Any application of the math to the area around the star is useless with out this variability factor.

Regarding non-habital zone planets, Debes, Steinn, Sigurdsson/ Ehrenreich, Lecavelier Des Etangs, Beaulieu/ and Fu, O'Connell, Sasselov, have published papers on extra solar planets heated by the tidal effects of a satellite. — Preceding unsigned comment added by 99.18.86.53 (talk) 15:21, 6 December 2011 (UTC)

Red dwarf habitable zone

A pair of articles of possible interest:

• Joshi, Manoj M.; Haberle, Robert M. (2012), "Suppression of the water ice and snow albedo feedback on planets orbiting red dwarf stars and the subsequent widening of the habitable zone", Astrobiology, 12 (1): 3–8, doi:10.1089/ast.2011.0668 {{citation}}: Unknown parameter |month= ignored (help)
• Choi, Charles Q. (February 23, 2012), "Extending the habitable zone for red dwarf stars", Astrobiology Magazine, NASA, retrieved 2012-02-23

Regards, RJH (talk) 21:57, 23 February 2012 (UTC)

Stellar Variability

I have a problem with this section, including the statement "as well as erode much of the atmosphere of any planet which does not have a strong magnetic field". This is not the case with Venus, which has retained a very thick atmosphere despite not having much of a magnetic field, and Mercury which has a magnetic field doesn't. I think this section, which also mentions radiation being harmful to life makes too many suppositions about life without addressing the core issue - whether water is or isn't present on the surface. Therefore I have rewritten the section. I think it needs to be about the broader subject which is the effect of space weather on habitability (ability to possess surface water) and therefore a planet's intrinsic ability to withstand it. I'm sure that life can find a way to protect itself against extreme radiation, such as the case of Deinococcus radiodurans. But realistically, this article is about surface water rather than life. --EvenGreenerFish (talk) 05:03, 23 May 2012 (UTC)

Update definition

Maybe this New Scientist article is too quick to draw conclusions, but it seems like it should at least be mentioned in the article: Earth and others lose status as Goldilocks worlds --Waldir ^talk 22:46, 2 February 2013 (UTC)

http://arxiv.org/abs/1303.7079 New paper submitted to Arxiv shows discusses that habitable zones extend inwards under certain circumstances. --Artman40 (talk) 03:53, 29 March 2013 (UTC)

Speaking off the cuff, based on what we know about exoplanets, extremophiles, and moons like Europa and Titan, I think the entire concept is up in the air at this point. It would help if someone would eliminate the criticism section and incorporate it into the body of the article. Viriditas (talk) 04:01, 29 March 2013 (UTC)

FWIW - I *entirely* agree w/ Viriditas - by coincidence, I initiated a similar, possibly relevant, discussion (re exoplanet PH2 b) not too long ago - if interested, the discussion is at the following => Talk:PH2#habitability - in any case - Enjoy! :) Drbogdan (talk) 04:30, 29 March 2013 (UTC)

Basically, I think the astronomy books are being rewritten based on the Kepler data at this point. (Ronald Gilliland said that, not me). Viriditas (talk) 05:37, 29 March 2013 (UTC)

The following paper called "The habitable zone of Earth-like planets with different levels of atmospheric pressure" was also released which showed that habitable zone is more lenient on Earth-like planets with higher average atmospheric pressures. --Artman40 (talk) 10:19, 29 March 2013 (UTC)

"A revised estimate of the occurrence rate of terrestrial planets in the habitable zones around kepler m-dwarfs", by Ravi Kumar Kopparapu, has been accepted for publication in The Astrophysical Journal, and redefines the boundaries of the habitable zone to include more potential planets. Kopparapu's website states that another paper, estimating dependence of habitability on planetary mass, is in the works. Between these two papers I think that we have a goldmine of information to add to the article. And I agree with you, Viriditas, estimates even from 3-5 years ago are irrelevant, and so our article will be if we do not modify it to keep abreast of the latest research. Wer900 • talk 16:56, 29 March 2013 (UTC)

New paper called " Towards the Minimum Inner Edge Distance of the Habitable Zone" was also made available. This takes humidity into consideration and presumes that the inner edge of habitable zone around Sun-like stars can be nearly 0.5 AU, well within orbit of Venus. It also predicts the first habitable world to be a hot desert planet because its easier to characterize their atmosphere. --Artman40 (talk) 04:34, 15 April 2013 (UTC)

Rewriting of article

I am currently rewriting this article, and will be creating new articles for the concepts of the galactic habitable zone and the recently-announced circumplanetary habitable zone. My work-in-progress can be found here. 23:40, 24 April 2013 (UTC)

Are you sure that "circumplanetary habitable zone" is sufficiently notable for an article of its own ? Google returns 4 results for the phrase including one very recently published article. I would imagine that it should be detailed under natural satellite habitability instead ... --EvenGreenerFish (talk) 01:42, 8 May 2013 (UTC)

I'm done with the article. Wer900 • talk 05:02, 3 May 2013 (UTC)

That's great, but in the future, please don't do cut and paste moves. I'm attempting to fix this now. Viriditas (talk) 09:16, 3 May 2013 (UTC)

Move rationale

I moved this page to its current title from habitable zone because I plan to create articles on the galactic habitable zone and the circumplanetary habitable zone (or "habitable edge"). Even though we have a WP:COMMONNAME policy, it would be best to disambiguate; besides, "circumstellar" is not overly technical and has been used in the literature. Wer900 • talk 20:42, 3 May 2013 (UTC)

Well, I don't want to rain on your parade, and at this time, I don't really have a position on the matter, but previous discussion (many years ago) on this issue determined that the name wasn't common enough so they chose to go with habitable zone instead. You may want to develop a stronger argument before someone (not me) challenges your move. Viriditas (talk) 03:32, 4 May 2013 (UTC)

With planetary habitability being more and more searched about, I think that it is good to disambiguate right from the start to our readers that the "habitable zone" they commonly hear of is the circumstellar habitable zone, and not the galactic habitable zone, which I think will become more and more prominent in news reports as the rare-Earthers try to bite back at recent habitable-planet discoveries. Besides, our current technology is not very good yet; given five to ten years, we should be able to identify planets farther away, and possibly near the galactic center, that are habitable. Microlensing can already do that. We need to think ahead and disambiguate early on, because it is all but certain that the galactic habitable zone and circumplanetary habitable zone will become more and more relevant as time marches on. Wer900 • talk 05:18, 4 May 2013 (UTC)

Well, we've got the technology to examine ET atmospheres for biosignatures but nobody wants to pay for it. It's almost like the rare Earthers control the budget. Viriditas (talk) 05:23, 4 May 2013 (UTC)

Numerous Rewriting Problems

The spirit of the rewriting is generally ok, although I have some key concerns. Primarily the way the article now reads and the general tone. It article now assumes that water exists on any planet within the CHZ which is totally unprovable and that the article has once again become in many respects more or less a clone of planetary habitability. Also that recent studies are taken as gospel, rather than for what they are, still theories. For example the bit about circumplanetary habitable zones. This is very new research, yet the article makes it sound as though it is scientific dogma. Please avoid assertions such as "must be", "need to be", "cannot" etc, without a citation or if they have more than one reference.

The article now appears to take for granted some very wild speculation, for instance including artists depictions without presenting them as such. Thirdly, some of the statements are no longer supported by their citations. I'm assuming this is a slice and dice error rather than intentional and I intend to go through them in detail. But here is a classic example:

:The origin of water on Earth, for example, is likely the result of impacts with icy bodies, outgassing, mineralization, leakage from hydrous minerals from the lithosphere, and photolysis.[58][59]

This is definitely not what it said before. If you read the article Origin of water on Earth or accompanying citations, nowhere does it make this assertion. The newly written section not only misleads the reader into believing that the origin of water on Earth is known, but inevitable on any planet within the CHZ which is patently wrong.

GJ 1214 b[61][62] and Kepler-22b[63] are ocean planets with seas hundreds of kilometers deep...

Please, show me some proof of that. The citations do not make this claim, so the article shouldn't either.

The lead introduces a new definition .... sufficiently large planet ... Is it really necessary to include in the definition to constrain it to a size ? I mean it is possible for an extremely dense dwarf planet or even asteroid made completely of say iron to possess an atmosphere (for example of Xenon) and surface water. Titan is extremely low density but supports a dense atmosphere and liquid. What is to say that terrestrial planets extremely large compared to the Earth could not exist in the habitable zones. None of this is known definitively, therefore should not be introduced into the definition.

I think it is important to clarify to the reader for why liquid water is important ... there is now no notability assertion in the article ... and far too many assumptions. Why is CHZ important ? If at all.

Images are far too big ... refer to Wikipedia:Manual of Style/Images

Why has reference to SETI been removed ? Surely habitable zone is of importance to the search for both life and intelligent life elsewhere in the universe ?

--EvenGreenerFish (talk) 06:36, 4 May 2013 (UTC)

I'm almost wondering if we should restore the previous lead. The new lead is not an improvement. Viriditas (talk) 10:40, 4 May 2013 (UTC)

I do apologize for the errors in my rewriting. The material on SETI was removed because it is not really supportable (SETILive, for example, a project I am a not-so-active member of, only targets stars with Kepler candidate planets, not necessarily those with habitable candidates) at this point, although with later discoveries it may be when there is a sufficient sample size for a truly focused SETI effort. I guess I could add the relevance to METI, as habitable-zone planets have been the most likely destinations for messaging to extraterrestrial life.

I fixed ocean-planet comments to add uncertainty, as we're not sure that they are ocean planets or not.

The use of "sufficiently large planet" means "a planet sufficiently large enough to support an atmosphere conducive to life as we know it within the CHZ, where ultraviolet flux is high and gases such as methane and ethane degrade rapidly." Titan couldn't exist because its methane would be photolyzed and then excited into space, and then its water crust would sublimate.

Kopparapu is accepted as "gospel" because it uses better climate models and supercomputers than would be available to, say, Rasool and DeBurgh. Also, Kopparapu seems to be a middle ground between the optimists and the pessimists historically, with a relatively far outer edge (1.688 AU) and a far inner edge (0.99 AU). In consideration of all of the other estimates in the past, Kopparapu makes sense as a middle ground.

I think that the rewrite is already being worked on. I never envisioned this as the best version of the CHZ article ever produced, but I do see it as a major improvement over the previous article, in which everyone added the latest information to the lede by tacking on new sentences while never bothering to make necessary structural changes in the article. Such is, unfortunately, the case in many astronomy/physics articles. Wer900 • talk 17:14, 4 May 2013 (UTC)

Briny Water ... a criticism ... ?

The Criticism section now contains the following statement ...

The habitable zone has also been criticized because it does not take into account the fact that solutions, with water as the solvent, may retain a liquid state at temperatures or pressures that are not traditionally considered habitable.

It used to make sense as it was referring to compounds like ammonia (such as those likely present in the water on Enceladus and Ceres), but now somehow it weaves in the possibility of surface water on Mars without saying who has used this criticism

Furthermore ... its a very basic fact that the Earth's oceans are also comprised of briny water ... surely every climatologist predicting habitable zones would have taken this into account ... --EvenGreenerFish (talk) 05:12, 7 May 2013 (UTC)

Ocean water was not nearly as briny to begin with, so I highly doubt that brine has been considered. Oceans would evaporate or freeze without this brine if they were outside the conventional habitable zone. Wer900 • talk 20:08, 7 May 2013 (UTC)

That's exactly my point, Earth's oceans would likely freeze if it wasn't for the salt content - even inside the HZ (ie snowball Earth) ! Actually most sources I've found state that the ocean has probably always been salty (including the NOAA), albeit less so than now. Not to sound rude, but back to the point, is this section your own criticism of the HZ or that of a number of peer reviewed sources ? --EvenGreenerFish (talk) 00:34, 8 May 2013 (UTC)

It's not my own criticism, I merely reformulated what was in the previous Habitable zone article's criticism section. If you want to remove it, you are free to do so (no sarcasm intended).Wer900 • talk 04:34, 8 May 2013 (UTC)

Giant planet & mass ... relevance ?

The article contains the following:

At the same time, though, a planet or natural satellite must not have so much mass that it becomes a gas giant or ice giant.[7][8]

To me this awkward statement makes very little sense in the context of this article. Is it saying that gas giants can't exist in the habitable zone ? That once a PMO becomes a gas or ice giant it ceases to exist as a planet ? Or is it simply trying to say that such planets lack a surface (which is redundant as per the definition) ? Its citations are circular - ie merely what makes a planet a gas giant and not a terrestrial planet. And what is the bit about "so much mass" ?

It also appears to argue that it is inevitable for planets with lots of mass to become gas giants. Earth is most massive of the terrestrial planets in the Solar System and it is not a gas giant. There is no confirmed data on "terrestrial planets" which are much more massive than the Earth (ie Super-Earths). We do know that compact and relatively high mass planets like Mercury exist and there is evidence pointing to Chthonian type planets as well. Surely density should be considered along with mass in this context ? But what relevance does it have in context to the subject - the habitable zone ?

My primary issue with this new lead, like many previously stated, is these unequivocal assertions of planetary habitability that have crept back into the article. The core definition of "on the surface" was designed to preclude gas giants and there was a section in the lead explaining why this is so. The only real reason is inference and anthropic reasoning. For instance, Ward & Brownlee dismiss the claims of Sagan (who coincidentally is no longer cited in the criticism section - see Sagan, Carl. Cosmos. Episode 2. 1980) that gas giants can be habitable based on the fact that they are - well - gas giants and don't have a surface, plate tectonics, a moon or anything that makes them remotely "Earth-like". Now that that explanation is missing, this assertion lacks any real context. The inference that habitable zone theory bases all of our assumptions on Earth, however, remains super important and really should never have been removed from the article.

Water is in fact plentiful in the ice giants such as Neptune and Uranus and the possibility of oceans has been well explored - see "Liquid Water Oceans in Ice Giants" Wiktorowicz and Ingersoll 2006 just as supercritical liquid phases are likely also on gas giants. The reality is that all Sudarsky Class II planets within the zone are potentially "habitable" according to the broad astrobiological definition - water and a source of energy. There is just as little proof of water to existing in the liquid phase on gas giants as liquid water found on the surface of other terrestrial planets. Unless the definition is changed to remove reference to the surface, it definitely needs clarification in the lead. And despite indications otherwise, habitable zone remains a theory until direct evidence is found ... --EvenGreenerFish (talk) 08:05, 7 May 2013 (UTC)

FWIW - a recent discussion about PH2 b, a confirmed Jupiter-size exoplanet in the habitable zone of its host star PH2, may be *very* relevant (and *very* significant?) here - see => Talk:PH2#habitability - in any case - Enjoy! :) Drbogdan (talk) 13:28, 7 May 2013 (UTC)

Reliable Sources

Not to attack the credibility of any one source, but since the rewrite there are numerous references to a a site called "Centauri Dreams". I tagged the article with the "self published" tag due to my concern about use of it as a primary source.

From the source:

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities.

Although I’ve been writing about technology for over twenty years now, my focus has largely been on computing and the Internet. But behind the scenes I’ve continued to nurse an active interest in space travel, and the ultimate challenge: finding a way to reach the nearest stars. I have no idea whether people will ever travel between the stars or not, but I’m becoming convinced that robotic probes to explore nearby systems are forseeable.

I have no problem with citing the peer reviewed research itself, but citing this website in my honest opinion is definitely self published and not sufficiently encyclopedic.--EvenGreenerFish (talk) 17:21, 7 May 2013 (UTC)

Gilster is merely citing the existing peer-reviewed research; I only use him when I cannot immediately find the research itself. If you can find appropriate sources for the material presented, then you can do so. Otherwise, I feel that Gilster is fine, because I am only using his website as a reference to opinions that have been published in peer-reviewed channels, rather than those of Gilster's own originating. Also, Gilster wrote the book Centauri Dreams on the same subject (and the namesake of the blog), so I think that WP:SPS is narrowly met for the time being. Wer900 • talk 20:12, 7 May 2013 (UTC)

I removed the blog cite and replaced it with an appropriate journal cite, the only Gilster cite I have now is one for his book Centauri Dreams (which was published by Springer). Wer900 • talk 20:33, 7 May 2013 (UTC)

Thanks, but I note that Glister citations keep springing up in the article. Currently citations 18, 33 and 88 all cite the website "Centauri Dreams". The thing is, from memory at least some of these statements already had sufficient scientific sources ... --EvenGreenerFish (talk) 05:28, 26 June 2013 (UTC)

Chemistry ?

Someone has added a new parameter, chemistry, to the definition despite this additional criteria not appearing in any of the definitions discussed here to date. This definitely needs explaining, otherwise it should be removed. I mean, of course, you'd need hydrogen and oxygen to have water - duh. Really, I could think of a hundred different conditions to add. But realistically this is not planetary habitability, it is about the habitable zone ... a location ... not all the ingredients for habitability. Nowhere should it assume that the zone is a case of "just add water", so it doesn't have to be explicitly stated in the lead. --EvenGreenerFish (talk) 03:29, 25 May 2013 (UTC)

Agree. And, not to beat a dead zebra, but let's not forget, the CHZ is showing enormous geocentricity & anthropocentricity.... Sarek of Vulcan ^{I know what you're thinking} 04:58, 25 May 2013 (UTC)

SETI keeps getting removed

Can we please have some discussion on this. A particular editor keeps removing SETI and replacing it with METI. Yet METI is a form of Active SETI and SETI came long before METI. The whole Waterhole concept which is the primary platform upon which SETI efforts have operated for at least half a century has been based on the CHZ premise and is also a reason for the significance of the Wow! signal. The Allen Telescope Array is actively searching CHZ candidates, afterall this is featured in the article on Extraterrestrial life and the US government's response to its existence. This work should not be ignored in favour of relatively futile efforts to messages to aliens on planets some of which have not even been confirmed to exist. I would strongly argue that this sentence, which is adequately cited remain at the very least.

The waterhole, which is based on the properties of water has been used in the search for extraterrestrial intelligence (SETI) since the mid 1960s by pioneers such as Frank Drake and CHZ candidates are seen as priority targets by many scientists.

--EvenGreenerFish (talk) 05:10, 9 June 2013 (UTC)

EverGreenerFish, you're confusing two things. The waterhole is not based on the properties of water, it's based on the properties of neutral molecular hydrogen.

Actually, no I'm not. The waterhole IS based on water, of which hydrogen is simply an element. This is from the Waterhole article " The term was coined by Bernard Oliver in 1971.[1] The strongest hydroxyl radical spectral line radiates at 18 centimeters, and hydrogen at 21 centimeters. These two combined form water, and water is currently thought to be essential to extraterrestrial life advanced enough to generate radio signals. Bernard M. Oliver theorized that the waterhole would be a good, obvious band for communication with extraterrestrial intelligence." I am happy to reword this to something similar, so that it can fit in to this article, because its more important by far than METI.--EvenGreenerFish (talk) 05:26, 26 June 2013 (UTC)

References

Earth Similarity Index (ESI) values for planets in the zone

Someone keeps putting ESI values into this article. My issue with this is that those are generally uncited and apparently inaccurate. For example Gliese 667 Cc, it is claimed without citation has an ESI of 0.79, yet the value given by several searches of the Internet including http://phl.upr.edu/projects/habitable-exoplanets-catalog/data is 0.82 (and was previously listed as 0.85). Though CHZ is generally more accurately calculated on Earth properties, I'm not convinced of the necessity of these figures in this article. Their presence has too much potential to be used to for or against case of habitability, whereas that is not really what this article is about. Futhermore, generally single detection methods produce alternate readings, for example transits produce ranges or in the case of radial velocity where several possible planetary configurations are proposed, there can be multiple possible ESI values. And we really don't know the actual surface temperature of these planets anyway. I strongly believe that planetary habitability should be fleshed out on the corresponding planet or star's article. Only evidence of the presence of water would really be relevant to this article.--EvenGreenerFish (talk) 05:06, 29 June 2013 (UTC)

Habitable zone extends inwards with tidally locked planets

According to new paper, on tidally locked planets, cloud cover helps to stabilize the planet's climate even when the planet has relatively high humidity. --Artman40 (talk) 16:55, 3 July 2013 (UTC)

Malware Link Removal

• Potentially Malicious Domain: (EXPLOIT, RBN Known Malvertiser IP 22)
• hxxp://www.dailygalaxy.com/
• https://www.virustotal.com/de/url/06f7d7c43c549e5e370a1e64d961bbbb9f4be55c29111d41e93ae9bb66489f23/analysis/1374427632/
• JS/Exploit-Blacole.cw
• https://www.virustotal.com/de/file/5ea1609b649e14ccfd84fec0d7e9d13cb0f885876f0ef5fae0407d23490ecddc/analysis/1374428349/
• https://www.virustotal.com/de/file/192346fedd2cc52353f89fd93fe1da383b6fa8a969c4c27f1fa663d4a40c3ae4/analysis/1374428351/
• https://www.virustotal.com/de/file/2656324fdda8179413cf416bd559e5f6f13864886a6d31907928e6334e64ebfa/analysis/1374428355/
• https://www.virustotal.com/de/file/a9dc933ca440b54c82be1fc9a71df252cf738ca3d908814adc656d9ffcc7c6ed/analysis/1374428365/
• https://www.virustotal.com/de/file/42430671c0fd1332eeb990373a1707da334520e2bae48d1dc9ee6df47b728125/analysis/1374428367/
• https://www.virustotal.com/de/file/8eb65132b441b07193c467814570e2c0959ceff07e35149247f531dde514782f/analysis/1374428377/
• REFERENCE: http://jsunpack.jeek.org/?report=49695ac9748fc84c3953dd8db54a661f52fd8be4
• http://urlquery.net/report.php?id=3902995
• SEE ALSO:
• http://quttera.com/detailed_report/www.dailygalaxy.com
• http://sitecheck.sucuri.net/results/www.dailygalaxy.com
• http://www.UnmaskParasites.com/security-report/?page=www.dailygalaxy.com

--Gary Dee 18:41, 21 July 2013 (UTC)

I suggest that you stop removing dailygalaxy.com links, because they are not malicious.--Anderson I'm Willing To Help 23:13, 22 July 2013 (UTC)

Outrageous POV

"Red dwarfs that have masses less than 20 percent of that of the Sun cannot have habitable moons around giant planets, as the small size of the circumstellar habitable zone would put a habitable moon so close to a star that it would be stripped from its host planet. In such a system, a moon close enough to its host planet to maintain its orbit would have tidal heating so intense as to eliminate any prospects of habitability."

This is so blatantly anthropocentric, it beggars the imagination. Are we to utterly ignore the very prospect life may not resemble Man in even the tiniest respect? And that is even disallowing biology not relying on carbon...

Would someone care to tell me if a chemotroph, such as those found even in Earth's own oceans, could happily live on a moon tidally locked as described? I imagine such a lifeform could survive quite nicely. So we've proven the claim untrue without even finding E.T. Should this claim then survive inclusion unchallenged? TREKphiler ^{any time you're ready, Uhura} 00:46, 30 July 2013 (UTC)

The chemotroph wouldn't survive because of a lack of water. Amino acids and the ingredients of terrestrial biochemistry have been created many times in lab experiments, but other biochemistries are harder to create, and hence less common. No organism can survive conditions more intense than those on Io for more than a short time. Wer900 • talk 01:28, 30 July 2013 (UTC)

kepler 186f - Earth Analog ??

Not enough is known about Kepler 186f to make the call that it is an Earth Analog. Just being the size of the Earth in the habitable zone does not cut it. Especially since it is orbiting a different kind of star .... --EvenGreenerFish (talk) 23:45, 17 April 2014 (UTC)

Yes. Changed it. Astredita (talk) 23:49, 17 April 2014 (UTC)

Gliese 581d etc

An anonymous editor has noted that GJ 581 d and g have been recently disconfirmed. I changed the word "disproved" to "disconfirmed" because I think it is more neutral. Proof is final and there will be doubtless further debate about the status of these planets. There are still several references to GJ 581 d in the text and an image that features both it and 581 g. I think further changes are needed to reflect GJ 581's downgrading as a habitable system. Qemist (talk) 23:32, 4 August 2014 (UTC)

Triple point of water at known atmospheric pressures and temperatures

I think it would be useful to illustrate the concept with a phase diagram with the relative atmospheric pressures and temperatures of the planetary mass objects indicated. I have mocked something up here, but I'd like it to be as accurate as possible.

• Earth = 101 kPa at sea level avg temp 16°C
• Venus = 93 bar at surface temp 462°C
• Mars = 600 - 1,115 Pa (Hellas Basin) temp -125 to 20°C (the range indicated on the graphic should be smaller I know)
• The Moon = ~0 kpa temp -233 to 123°C
• Ceres = ~0 kpa temp -105°C

What it illustrates is that the atmosphere of Earth and Mars might actually be quite thin for habitable planets and that the thicker an object's atmosphere, the wider the habitable zone is, conversely, the thinner, the narrower. It shows that if the atmosphere (such as if it had slightly higher mass/gravity), it could have supercritical liquid water on the surface. Provided that there is a mechanism to regulate the temperature and pressure,such as either a source of heat retention (from radiant energy or given the relative amount of internal energy that PMOs can generate) or sufficient cooling through albedo. At these high pressures, the line between warm water and thick atmosphere becomes somewhat blurred.

What this shows is that (minus the sublimation caused by UV radiation and the sputtering and atmospheric effect of the Solar Wind), water on the Moon should sublimate, wheres water on Ceres, should remain ice.

What it also illustrates is that it is actually possible for a planet with a large atmosphere to possess liquid water even if the temperature is lower than zero.

What would also be useful to see is how these ranges are affected by common solvents, such as Earth's saltwater ocean and briny water on Mars that effectively move the triple points.

Derived from 'Phase diagram of water including high-pressure forms' by Cmglee CC BY-SA 3.0

Can anyone see any issues with adding such a graphic to the article?

--EvenGreenerFish (talk) 12:47, 6 October 2015 (UTC)

Habitable Zone vs Circumstellar Habitable zone

I've been reading dozens of studies recently about Habitable Zones. I have yet to find one that refers to them by the term "circumstellar habitable zone" or CHZ. All of the studies I've read use the term "habitable zone" and HZ. I think the article needs to be tweaked to use the habitable zone rather than cicumstellar habitable zone, including the title. The redirect should be from circumstellar habitable zone to habitable zone, and not the other way around. — Preceding unsigned comment added by 67.190.18.116 (talk) 23:47, 25 September 2016 (UTC)

You were reading about habitable zones around stars. The studies were all about habitable zones around stars and you knew that. There was no ambiguity. In an encyclopedia, particularly one with hundreds of thousands of articles, specificity is key. More to the point, the title is accurate and succinct. People may type in "habitable zone", and they will be directed to the most likely thing they are looking for; in this day and age, that is "circumstellar habitable zone". There are other uses of the term "habitable zone", and there is no need to dumb down Wikipedia just because studies about habitable zones around stars aren't named fully and accurately. I bet those studies use a very wordy description of their subject in a subtext to the title. There is an article about galactic habitable zones; should that also be called "habitable zone"? If the two articles are merged, should the two concepts both be called "habitable zone", or would you prefer "habitable zone around stars" (HZAS) and "habitable zone in galaxies" (HZIG). Then there's circumplanetary habitable zones, which are also referred to in this article... I think I've made my point. At least I try (talk) 11:07, 26 September 2016 (UTC)

Habitable Zone vs Circumstellar Habitable zone

I've been reading dozens of studies recently about Habitable Zones. I have yet to find one that refers to them by the term "circumstellar habitable zone" or CHZ. All of the studies I've read use the term "habitable zone" and HZ. I think the article needs to be tweaked to use the habitable zone rather than cicumstellar habitable zone, including the title. The redirect should be from circumstellar habitable zone to habitable zone, and not the other way around. — Preceding unsigned comment added by 67.190.18.116 (talk) 23:47, 25 September 2016 (UTC)

You were reading about habitable zones around stars. The studies were all about habitable zones around stars and you knew that. There was no ambiguity. In an encyclopedia, particularly one with hundreds of thousands of articles, specificity is key. More to the point, the title is accurate and succinct. People may type in "habitable zone", and they will be directed to the most likely thing they are looking for; in this day and age, that is "circumstellar habitable zone". There are other uses of the term "habitable zone", and there is no need to dumb down Wikipedia just because studies about habitable zones around stars aren't named fully and accurately. I bet those studies use a very wordy description of their subject in a subtext to the title. There is an article about galactic habitable zones; should that also be called "habitable zone"? If the two articles are merged, should the two concepts both be called "habitable zone", or would you prefer "habitable zone around stars" (HZAS) and "habitable zone in galaxies" (HZIG). Then there's circumplanetary habitable zones, which are also referred to in this article... I think I've made my point. At least I try (talk) 11:07, 26 September 2016 (UTC)

No, the term in multiple studies is "Habitable Zone" with the abbreviation of "HZ". This is so common, that the inclusion of "Circumstellar" is the outlier. When talking about galactic HZ, they actually spell that out. I can start listing studies. These are not uncommon ones. They are well referenced and heavily cited. Justification provided in your replay is borderline OR for the inclusion of "Circumstellar". That is your conclusion you reached yourself in order to make sense of it in your mind for reasons you believe to be important to yourself. It is not the more common term. — Preceding unsigned comment added by 2601:280:4900:8BE1:853C:35A0:C00F:72B7 (talk) 05:36, 28 September 2016 (UTC)

Ammoniates

The article mentions ammoniates. Looking for this concept in wikipedia, one finds several articles containing ammoniate+something, but apparently there is no place in wikipedia where ammoniates are defined or otherwise explained. May someone who knows about this fill this gap. (I am interested in this question also as a simple reader.) --UKe-CH (talk) 09:54, 6 October 2016 (UTC)

That would be a compound that contains ammonia, which lowers the freezing point of water. BatteryIncluded (talk) 11:34, 6 October 2016 (UTC)

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Number of planets needs updating

The number of planets in the Goldilocks Zone needs updating, and from multiple sources/estimates. 2013 is WAY out of date. Misty MH (talk) 08:31, 2 August 2017 (UTC)

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Violation of copyright laws

In the course of translation of this article from English to Japanese Wikipedia, I found some sentences violating copyright laws (i.e. Wikipedia:Plagiarism.) The second paragraph in the #Determination section were fully copied and pasted from this paper. Could someone help me identify who the editor is, and instruct me how to properly report this issue? As far as I know from my experience with the Japanese Wikipedia, those plagiarisms should be removed first and then should be asked for deletion in line with WP:DEL-PROCESSES. I even suspect whether there are other plagiarisms in this article... Thank you in advance for your assistance. --ProfessorPine (talk) 03:31, 16 December 2019 (UTC)

Violation of copyright laws

In the course of translation of this article from English to Japanese Wikipedia, I found some sentences violating copyright laws (i.e. Wikipedia:Plagiarism.) The second paragraph in the #Determination section were fully copied and pasted from this paper. Could someone help me identify who the editor is, and instruct me how to properly report this issue? As far as I know from my experience with the Japanese Wikipedia, those plagiarisms should be removed first and then should be asked for deletion in line with WP:DEL-PROCESSES. I even suspect whether there are other plagiarisms in this article... Thank you in advance for your assistance. --ProfessorPine (talk) 03:31, 16 December 2019 (UTC)

• @BatteryIncluded: (current user name: @Rowan Forest:) According to WikiBlame, the tool to investigate plagiarism, you are the one who copied and pasted from the original work - inserted at 15:04, 3 May 2016 (UTC). As you created and added so many articles and sentences, I am very much worried whether you repeated the same practice not only on this Circumstellar habitable zone but also on other articles. You should thoroughly review your past edits, and then file requests for deletion as soon as possible. Until then, I would also suggest all of other editors to refrain from additional editing.

I, as a native Japanese speaker, am now investigating which Japanese articles would be affected due to innocent translation from English articles. So far, ja: ハビタブルゾーン (Circumstellar habitable zone on the Japanese Wikipedia) at least is strongly advised by a Japanese administrator/bureaucrat to proceed the deletion request immediately. My hands are full, so Rowan Forest's and other users' actions are much appreciated on the English Wikipedia side. --ProfessorPine (talk) 04:42, 19 December 2019 (UTC)

I reported this to 'the appropriate authorities' and the offending material has been cleared out. The consequence is that all subsequent amendments have also had to be removed, so a great deal of editor effort has been wasted. Rowan Forest needs immediately to identify and report other such errors of judgement because the copyvios need to be expunged from the history, not just the current version. If you fail to do so, a year-long editing ban wouldn't be excessive, IMO! --John Maynard Friedman (talk) 15:09, 19 December 2019 (UTC)

Thank you @Diannaa for the follow-on removal edit from the article, and @John Maynard Friedman for the reporting. Just in case Rowan Forest has not accepted my pinging, I left a message on his user talk page. In parallel, I filed a deletion request to the Japanese Wikipedia. With the enough number of supportive votes, the request will be accepted within a week, I guess. --ProfessorPine (talk) 01:25, 20 December 2019 (UTC)

Sorry to inform that so far, Rowan Forest seems to refuse amicable cooperation: see the detail on his talk page. I gave him the second alert, so let's wait and see for a while whether he would change his behavior - I believe everyone deserves another chance. Otherwise we probably had better think about Wikipedia:Contributor copyright investigations (CCI) as per Dianna's suggestion. @John Maynard Friedman: any thoughts/suggestions? --ProfessorPine (talk) 01:48, 21 December 2019 (UTC)

Again: the text and history were deleted all the way to 2016. I have no private duplicate records and don't know the substance of your claim. Cooperation on what? I keep telling you I'm am locked out, and talking in your Talk page is another Copyvio. Who has a bad behavior here? Rowan Forest (talk) 18:09, 21 December 2019 (UTC)

@Rowan Forest:, The administrator had no choice but to delete the offending material and thus all subsequent edits that might have been informed by it.

You are being asked two questions.

1. What reason can you give for having copied another person's work (for example, are you that person).

2. Which other articles have you edited to add stolen material as in this case.

Complete frankness is essential if you wish to continue being an editor. --John Maynard Friedman (talk) 19:13, 21 December 2019 (UTC)

Given your edit history, I know that you can do this yourself, but just so that there is no doubt, the Administrator's edit note says: remove copyright content copied from https://web.archive.org/web/20160602235333/http://veilnebula.jorgejohnson.me/uploads/3/5/8/7/3587678/lammer_et_al_2009_astron_astro_rev-4.pdf . Do you recognise it now? --John Maynard Friedman (talk) 00:10, 22 December 2019 (UTC)

FYI: In the PDF, use "photodissociation" as a search word. The second paragraph of Page 185 is the one copied and brought to Wikipedia. Hope this helps. --ProfessorPine (talk) 03:48, 22 December 2019 (UTC)

Sorry to inform all of you that Rowan Forest (former BatteryIncluded) did the same copyright infringement with First observation of gravitational waves at least in February 2016. This is a coincidence but ja: 重力波の初検出 was translated from First observation of gravitational waves and is now nominated for a Good Article (GA). As an active volunteer for the GA evaluation, I checked whether the English article contains stolen contents. See the second paragraph of UniverseToday.com's article and compare with Special:Diff/705815813/705821268 (edit by BatteryIncluded at 19:25, 19 February 2016 (UTC)). I will keep digging the edit history and inform you if I find more. I do not want to disturb many of you during the Xmas holidays, but now it is the time to file a complaint to Wikipedia:Contributor copyright investigations (CCI), isn't it? --ProfessorPine (talk) 08:05, 23 December 2019 (UTC)

Reported. Will do CCI next week. --John Maynard Friedman (talk) 11:46, 23 December 2019 (UTC)