Talk:Europa (moon)/Archive 1

Disambig
Shouldn't there be a disambiguation link at the beginning of this article?

Continent Europe naming
The continent 'Europe' was named after the word 'Ereb'. 'Ereb' means 'land of sun set' in ancient greek/latin.


 * Where does that come from? I thought the name of the continent had a mythological origin. Also, "ereb" isn't what you'd expect for either a Latin or a Greek word. --kwami 00:26, 11 Apr 2005 (UTC)

- i think europe and europa where named after the same person,

Ice thickness and composition
This article states:

"It has an outer layer of water ice thought to be around 100 km  thick

then later says:

"...based on this and on the calculated amount of heat generated  by Europa's tides it is predicted that the outer crust of solid   ice is approximately 10-30 km thick, which could mean that the   liquid ocean may be as much as 90 km deep underneath."

Am I correct in assuming that the first number refers to the thickness of the water AND the ice, combined? Not just the "water ice"?


 * I'm fairly certain that the first statement is referring to water ice as opposed to other ices, somewhat common in the outer solar system. But yes, it would include the liquid water as well. --Patteroast 22:02, 17 Apr 2004 (UTC)


 * I doubt that, because i presume: 1. the surface is water ice, 2. the interior becoming warmer inwards, which means that more volatile ices are melted earlier than the water ice, and being lighter will ascend towards the surface. I think, iff the numbers 100 and 90 are correct, that 100 refers to the layer of H2O, 90 to the subpart of H2O that is liquid, and therefore, implicitly, that the solid H2O layer is 10 km. Those figures seems to me to still be pretty accurate, although i think i remember that arguments exist that the water ice layer must be thinner than that. Rursus 13:00, 7 February 2007 (UTC)


 * NASA states that Europa's oceans may be up to 50 km deep at the deepest point. What's the citation for the 20 - 30 km deep?

NASA who? Anderson et al. (Europa's Differentiated Internal Structure: Inferences from Four Galileo Encounters, Science 281, 2019-2022) find the H2O layer is ~80-170 km thick based on Galileo gravity data (the whole water + ice layer, not just the ice layer), and nominally about 100 km thick. Subtract your favorite ice shell thickness, and you get the liquid ocean thickness.

Axial tilt
I noticed that this page does not have a value for Europa's Axial tilt...Does anyone know this value?

Unknown, but predicted to be very small, (9.65±0.69)×10−2: Bills, B.G., Free and forced obliquities of the Galilean satellites of Jupiter, Icarus 175 (2005) 233–247.

Data for Europa
I removed the paragraph below because it reiterates the article, or is trivially calculated from data in the table. None of the other Galilean moons have a similar paragraph.


 * Data for Europa:
 * Surface Gravity (Earth = 1): 0.135
 * Orbit Speed: 13.74 km/s
 * Escape velocity: 2.02 km/s
 * Surface Composition: Water Ice

&mdash;Herbee 16:45, 15 Jun 2004 (UTC)


 * In case you were curious why that was there, originally most of the planets and moons had a list of facts similar to this before the Wikiproject to give them all a uniform table started. I guess this just got missed during cleanup. :) Bryan 00:55, 16 Jun 2004 (UTC)

Galilean moon names
"Although the name "Europa" was suggested by Simon Marius soon  after its discovery, this name and the names of the other Galilean   satellites curiously fell into disfavor for a considerable time..."

I've heard speculations that Marius invented the names just to annoy Galileo. These names probably weren't considered appropriate as they were named after the lovers of Zeus -- especially with the case of Ganymede, who was male. --Jyril 23:07, Feb 27, 2005 (UTC)
 * Ganymede was a godified servant of the olympian gods, not anything else! Basta!! Those rumors don't respect myth. Rursus 13:22, 7 February 2007 (UTC)


 * Umm, I hate to burst your Disneyland idealism of Greek myth, but male-male relationships between gods and mortals (and mortals and mortals) are a common theme.--Scorpion451 17:14, 5 July 2007 (UTC)

Fact garble in Etymology section
Before doing anything about the text: Now, my trouble is this: i wish to change, which necessitates deleting the above mentioned explanation, but i wish to replace it with a reasonable explanation of why the Io/Europa/Ganymedes/Callisto tetrad is used nowadays? So my question is:
 * 1) I claim that Jupiter I, II, a.s.o. numbering refers not to the from-in-to-out order of the satellites, but to the discovery order, and in cases of simultaneous order, to an arbitrary but static order kept by the astronomer collective (a so called convention). This means that explaining the introduction of the modern person names, to be caused from confusion created by new discoveries, is an erroneous discourse (fact garble).
 * 2) I claim that the numbering is still used for some unexplicable reason (maybe redundancy as per linguistics??, or as a discovery order mark), such as for example in "Astronomy - structure of the Universe", Roy &amp; Clarke, ISBN 0-85274-082-4, page 112.
 * WHY??! did the convention change from Jupiter II to Europa??

Said Rursus 13:22, 7 February 2007 (UTC)

geysers
shouldn't the geysers be mentioned? kwami 12:30, 2005 May 6 (UTC)


 * I don't think there are geysers on Europa. You may be thinking of Enceladus or Triton. The Singing Badger 19:16, 10 May 2005 (UTC)
 * Yup, eruptions off the limb of Europa were imaged by Voyager, and recognized some weeks after the flyby. Not as numerous as the Ionian eruptions, of course. I don't recall anything similar from the Galileo mission. kwami 10:14, 2005 May 30 (UTC)


 * Could you verify that claim? As far as I know, geysers on Europa are still hypothetical. Galileo orbiter tried to detect them, but was unable to find any. Galileo images show very smooth plains between the cracks suggesting that there may have been active cryovolcanism recently. But no active geysers/cryovolcanos have been detected.--Jyril 13:47, May 30, 2005 (UTC)
 * I've been unable to find anything online. I remember the interpretation of the plumes on Europa's limb was rather speculative. Perhaps it turned out to be something else, which wasn't news, so there was no followup to the story? I'll keep looking, or try writing someone at JPL. kwami 17:21, 2005 May 30 (UTC)


 * Heard back from the NSSDC:
 * It is believed that the "plume" seen on Europa was actually an artifact of the Voyager vidicon system. A search for plumes using Galileo found none, so the question of geysers on Europa is still open. &mdash;kwami 03:45, 2005 Jun 17 (UTC)


 * Correct. See section 5.2 of: Pappalardo, R.T., et al., Does Europa have a subsurface ocean? Evaluation of the geological evidence, J. Geophys. Res. 104, 24015-24055, 1999.

Pronunciation
Instead of the pseudo-phonetic transcription, I replaced it with what seems to me as a reasonable phonemic transcription and a a sound file of my own Americanized English. I've intentionally avoided using any special IPA characters for stress and vowel length since they have a tendency to look very odd in some browsers. Change this if you want, but try to at least keep it phonemic, or we might get more disputes over which is to be conidered correct. Don't take the sound file as an excuse to start bickering over the merits of various varieties of English. It's not supposed to be canon, and anyone listening to the sound file will at once know how to pronounce it in their own dialect/accent.

Peter Isotalo 13:13, May 29, 2005 (UTC)


 * We have the same cross-dialectical spelling pronunciation for all of the moons of the solar system and most of the first thousand asteroids. Add the IPA if you like, but don't delete the other. kwami 19:36, 2005 May 29 (UTC)


 * Oh, for crying out loud... Did you even notice that it wasn't accepted too well by non-native speakers? I was trying to avoid that.
 * Peter Isotalo 09:41, Jun 5, 2005 (UTC)


 * If you put in an IPA pronunciation, people start complaining about dialect chauvinism. (Maybe not a problem with Europa, but certainly a problem elsewhere.) Plus, half the English-speaking world doesn't have a clue what the IPA even is, let alone are able to use it. Rather than learn, they'll just ignore it. If it's useless for half the population, and contested by the other half, why should we try to make it the sole representation of English pronunciation? If you can figure out a way to transcribe into the IPA so that it represents all major English dialects, that would still only address half the problem. (I'm missing too many low vowels to attempt it.) Ideally we would have both. kwami 09:59, 2005 Jun 5 (UTC)


 * Pseudo-phonetic orthographic transcription seems like something people could fight about for ages as far as I can tell. At least IPA is as close to a neutral standard as one can get, and it is certainly not something exclusisve to English speakers. Now, if you actually take some time and read the transcription you'll notice that I deliberatly made it phonemic instead of phonetic. In other words, it's perfectly dialect-neutral.
 * Peter Isotalo 22:56, Jun 6, 2005 (UTC)


 * Yes, but it's only dialect-neutral for Europa. Your approach won't work for all the moons, because English dialects differ in their phonemic inventories, unless you specify that there is not a one-to-one correspondance between sound and symbol. Then people will argue with you about that, claiming that the IPA is supposed to be one-to-one.


 * We've also had very few problems with the spelling pronuciations. (A couple people didn't like the digraphs ah and oh, so we changed them to aa and oe, but that's it.) I don't see any problem with having both. At least now you have something to work with, which wasn't the case when I started. Oh, by the way, the spelling pronunciation is also phonemic, not phonetic (pseudo or otherwise). kwami 23:37, 2005 Jun 6 (UTC)


 * Couldn't keep my fingers away: let's spell [ju:rəʊpə] in Swedish: Joreupö, or German: Juröupö, or French: Yujeu-ou-peu? Twirling his moustaches, does: Rursus 16:29, 9 February 2007 (UTC)

P.S. The adjectival form Europan is fairly common in the literature. kwami 02:31, 2005 Jun 24 (UTC)

Orbital inclination to the ecliptic = 25,04 degrees?
Europa's orbital plane is practically the same as Jupiter's equatorial plane which is tilted only 3 degrees with respect to its orbital plane, which itself has an inclination of only a little more than one degree; so the tilt of Europa's orbit as referred to the ecliptic plane should never exceed a few degrees, as it is the case for the other three Galilean satellites as well. The figure of 25 degrees may be the tilt of Europa's orbit with respect to the celestial equatorial plane and not to the ecliptic, anyway, I suspect none of these needs to be mentioned under the "orbital characteristics" label. Just the inclination to Jupiter's equator is fine, and the celestial coordinates of Europa's north pole may be added if necessary. Allison Connors 29 June 2005 19:07 (UTC)


 * Well spotted. The mistake had spread, and is now fixed. Thanks!
 * Urhixidur 2005 June 30 03:06 (UTC)

Atmosphere
A far as I know, the "recent observations" using the Hubble Space Telescope that revealed a tenuous oxygen atmosphere were made in 1994 and the results published in 1995 (just google 'hubble europa oxygen'), so this is old news. I'm modifying that part. --201.236.39.22 01:54, 18 December 2005 (UTC)

Additions + let's make an FA
I have expanded the beginning of this page and created two small sections on etymology and orbital characteristics. There is some redundancy between the table and the body now but I think this is acceptable, given that many will simply sit down to read a page and not pick through charts and tables and what not.

Also, while I assume there's some attempt to standardize the natural satellite pages, I'm thinking Venus offers a good template for what we might do here and I have arranged the sections to this end. It's our only planet or satellite Featured Article at the moment and I see no reason why Europa can't be our second. Marskell 09:51, 3 February 2006 (UTC)

Units of Eccentricity
Eccentricity is a dimensionless number; surely expressing it in degrees is incorrect?

83.67.5.25 17:44, 2 March 2006 (UTC)


 * Definitely incorrect. Degrees make no sense here.--Jyril 18:17, 2 March 2006 (UTC)

Description of Age
This content in the "Surface" section doesn't make sense to me. "...the surface is about 60 million years old (plus or minus a factor of 3)." Does it mean from 20 to 180? Or 57 to 63, or what? Factors usually involve multiplication/division - not plus/minus. Peter 01:58, 31 March 2006 (UTC)


 * Usually, yes, but in this case, no. The intent is 20 - 180 Myr.  See the work of:

Zahnle, K., L. Dones, and H. F. Levison, Cratering rates on the Galilean satellites, Icarus, 136, 202-222, 1998. Zahnle, K., P. Schenk, H. Levison, and L. Dones, Cratering rates in the outer Solar System, Icarus 163, 263–289, 2003.

life on Europa
There doesn't seem to be too much in that article about the possibillty of life on Europa. There should be secetion about the possibilty of there being life on Europa.--Scott3 01:07, 7 June 2006 (UTC)


 * Wikipedia isn't the place for speculation. We have no idea if anything is swimming around beneath the ice, and probably won't know for a long time. All we know is that the ocean either isn't or is inhabited, which is like CNN saying that Osama bin Laden is dead or alive.--Planetary 08:24, 29 August 2006 (UTC)


 * WP:NPOV: "Assert facts, including facts about opinions — but don't assert opinions themselves." It is quite reasonable for us assert that other's have speculated on life, without presenting any given speculation as fact. Surely we can find the material for the suggested section or too add to the paragraph already present in exploration. Marskell 08:46, 29 August 2006 (UTC)

I agree that it is quite resonable to add facts about arguments for life on Europa. There are many articles in Wikipedia based on theories, that have only logical proofs. Matt. P 10:19, 31 August 2006 (UTC)

Greenberg
To mention this person 4 times in a section were he is representing only one half of the comunity is a little to much! Others do also research and they are not listed four times.--Stone 09:00, 10 August 2006 (UTC)

Agreed--edited out.

Terrestrial Microorganisms Could Survive the Trip?
Was it really necessary to crash Galileo into Jupiter? I would think that the icy cold vacuum of space, along with cosmic rays, would have killed any microorganisms present on the spacecraft.

Planetary protection deals with this problem. Experimental work points out, that Bacillus subtilis and deinococcus radiodurans are able to survive nearly anything.

GA review
This article nearly satisfies the qualifications. I have some suggestions for improvement before I approve it as a Good Article.


 * Cut down a little on the back-story of Europa in the Etymology section. Some of that seems to be unnecessary trivia.  What would be useful is info on why it was named Europa, and who first named it.
 * "This heats the body, and allows for geology" (Orbital characteristics section). This statement seems a little ambiguous, perhaps a little expansion on this thought would help clarify things for the casual reader.
 * Add citation(s) to the Internal structure section.
 * Instead of specifying which scientists believe what (Subsurface ocean section), simplify to something like "Some scientists believe(citation)...however, others argue(opposing citation)..." -- Its pretty much a universal consensus -- Nbound
 * The image on the left in the Possible life section seems disruptive to the flow of the article: consider moving it and/or replacing it.
 * In general, more inline references to the sources you have used (i.e., use the  notation.  This helps readers looking for more information find the specific source that might help them the most.-- The current format seems to work fine =S -- Nbound
 * A minor copyedit for grammar and clarity. -- added tag =) -- Nbound
 * Fix Etymology naming garble. (see above!) Rursus 13:30, 7 February 2007 (UTC)

Feel free to leave a message on my talk page if you have any questions or disputes.-Runningonbrains 12:58, 25 September 2006 (UTC)

GA re-review
I would advise against merely putting a cleanup tag on the article. This article does need a copyedit to remove fragment sentences, split run-ons, a few spelling errors. I am only permitted to keep this nomination on hold for 7 days, and trust me, from working on my own articles, cleanup tags get nothing done. I would suggest either doing it yourself, or contacting someone you know to do it. Unfortunately it would create a conflict of interest if I made any major changes, otherwise I would offer. A few more things: "Galileo imaging team member Richard Greenberg has used his research group's analyses of Voyager and Galileo images of Europa to argue that Europa's geological features also demonstrate the existence of a subsurface ocean."

While the Galileo spacecraft is wikilinked, at least a brief mention of what it is should be included in the article. This occurs a few more times in the article at various points.

(Its was called the "Galileo probe" earlier in the article" -- Nbound 01:57, 27 September 2006 (UTC))
 * Adding a brief phrase like "the Galileo probe, which orbited Jupiter and studied Europa in (time)," would suffice. -Runningonbrains 03:11, 27 September 2006 (UTC) (fixed -- Nbound)

One thing I missed before, Possible life is a stub-section, and has no citations. This should be fixed.

And while this isn't required, I do recommend using the  notation for major facts. Even if the source is referenced somewhere else, if someone wants to know more information about a certain aspect of Europa it greatly helps to have a reference nearby.

If you feel it would be a rush to get all this done in less than a week, I would suggest just re-nominating this article at a later date. In the time between, I would suggest requesting a peer review, to get more than just my opinion on the quality of prose in this article. As it stands right now, I do not believe this is quite a good article, however, with some tweaking, it could easily make it.

-Runningonbrains 04:23, 26 September 2006 (UTC)

source for the etymology
i didn't mean to start an edit war by putting back the tag.. but i don't think it's to much to ask to cite a source somewhere in the etymology section? i mean, that information has to come from somewhere.. the argument that it isn't cited on the other wikipedia articles isn't valid, i don't think, since they aren't very well referenced either. Mlm42 11:10, 27 September 2006 (UTC)
 * and literature in there!--Stone 11:43, 27 September 2006 (UTC)

Failed GA
This article is not quite a Good Article. However I have created a "To do" list at the top of this page. When these are done (aside from the references, which is not required, only a suggestion), re-nominate the article, and it should pass fairly easily. -Runningonbrains 19:14, 28 September 2006 (UTC)

Possible life on europa
I do not like it to put a big section into a enceclopedia article about something real like europa, which is so far from reality like the hypothesis about life on europa. Make a new article saying highly fictional hypothesis or science fiction or what ever. Everybody arguing that scientists come up with this does not make it more real. The Scientist play with scientifical fantasy about things they have no date. Everybody who belives in these hypothesis should first read an Science article about the life on Mars publishe few jears bevor the Mariner probe destroyed all hopes. This article states life on Mars as a fact and only deals whit the exact way the martian oecosystem works. Be careful with all this and wait for the landing operation planed for this century!

If anybody wants to extand the life on europa section here is some literature! --Stone 07:16, 29 September 2006 (UTC)

Not Epsom
The Subsurface ocean section equalled Magnesium sulphate (MgSO4) with Epsom salt (mineral), which is not correct, since chemical compound names (MgSO4) use to refer to many minerals, defined by approximate chemical composition, crystal structure, crystal water and similar crystal lattice extra molecules. I'm not quite sure, but i'll wager a great deal on the bet that the MgSO4 on Io, is not exactly Epsom Salt. Hehe (giggering evilly, does: Rursus 13:44, 7 February 2007 (UTC))

Eccentricity
The eccentricity of Europa is 0.0101 according to JPL's Horizons website and the books The Planetary Scientist's Companion, Planetary Sciences, and Europa: The Ocean Moon. I have not been able to find any reference for the number given, 0.0094.

128.32.149.56 17:43, 28 March 2007 (UTC)PtysGrl
 * It's great that you have a reference - put the new number in! and add the reference in line...
 * The only reasons the previous eccentricity edits were reverted was that 1) they broke the infobox format (eccentricity did not appear at all); and also 2) because the infobox should just have the actual observed eccentricity, while discussion of what part is forced etc should go somewhere in the text. Deuar 19:24, 28 March 2007 (UTC)

I tried to edit the page, which I guess means I broke it. Sorry! This is the first experience I have had editing a wiki page. If you (or anyone else reading this) could change the eccentricity, that would be great. I am clearly incompetent when it come to wikis.

I checked the reference given in the page, and it does link to a website with the value of 0.0094. However, it is generally accepted (and cited in the literature including a different webpage by the same people) that Europa's eccentricity is 0.0101. I pointed out the free and forced eccentricity simply because I thought might clear up why some older references state that the eccentricity is zero. Any eccentricity observed for Europa IS the forced eccentricity, and it's value is 0.0101, not 0.0094.
 * Aha, makes sense. Deuar 16:20, 30 March 2007 (UTC)

Sorry once again for the troubles!
 * Hey, don't worry, it wasn't a major problem. I really hope you don't get discouraged — we can use people who check the facts. They say that one of the main principles of Wikipedia is to Be Bold!.
 * I see that the reference for the 0.009 value is a NASA factsheet, and these tend to be out of date. Deuar 16:20, 30 March 2007 (UTC)

Is something missing?
Have a look at these sentences from the article - "Europa is also being gravitationally pulled in different directions by Jupiter and by other satellites of the planet (tidal flexing). This gives the body a source of heat and energy, allowing the subsurface ocean to stay liquified, and driving subsurface geological processes.[7]"

As far as I know tidal flexing has nothing to do with heat generation. Is there a sentence missing from the article?61.68.183.41 18:05, 28 March 2007 (UTC)
 * Tidal energy is dissapiated during the flexing (a classic example is to take a paper clip and bend it back and forth several times. The center of the bend will be hot).  I will clarify this. Michaelbusch 18:10, 28 March 2007 (UTC)

its because its orbit is so near to ganymede's witch is something like 5 times bigger than it —The preceding unsigned comment was added by Special:Contributions/ (talk)

Mars?
I reverted an edit that said Europa was a satellite of Mars. I assumed good faith and did not file a warning on the talk page of the user but just in case it happens again I'll document it here. JB Evans  23:02, 11 April 2007 (UTC) europas bigger then mars

Citation
Most of the inline citations are cite journal ones, although vite web would fit much better for newscientist and spaceweb.--Stone 23:20, 11 April 2007 (UTC)

Not Minor
Sorry for accidentally marking my last edit shouldn't have been marked as minor, it shouldn't have been. Neitherday 03:51, 12 September 2007 (UTC)

Success at GA
Yes, this is a good article. Succinctly, it fulfills all the good article criteria. I recommend nominating it for a featured article immediately. ScienceApologist (talk) 23:37, 26 December 2007 (UTC)


 * Please have the person who passed the GA add the correct template, which includes a date, oldid and topic. I do not participate in GA, and I have tired of tracking down faulty GA passes to prep the article for GimmeBot closing of FACs.  Sandy Georgia  (Talk) 05:14, 27 December 2007 (UTC)


 * Jeez, I think that all this "correct template" nonsense is really getting out-of-control. Anyway, I did it. ScienceApologist (talk) 18:50, 27 December 2007 (UTC)

OK; there are now way too many pictures
Either this article needs to be increased in size by about 150 percent, or some of the pictures need to be pruned, because right now this article is almost impossible to read.  Serendi pod ous  02:05, 1 January 2008 (UTC)
 * OK, I reordered the images and removed two which I felt didn't really add any new information. I think the page is much more readable now. I've also edited the captions down to stop the images crashing into each other. Serendi pod ous  02:14, 1 January 2008 (UTC)
 * I disagree with your assertion that the 2 images you deleted didn't add any new information. You deleted the only close-up of the Europan surface, and the only detailed image showing the variety of geological processes that are superimposed on the surface. Europa's fascination is mainly derived from its active geology and the amazing, alien-appearing surface manifestations of this geology, which are only visible in reasonably high-resolution images. At this point we have 3 such images; from my perspective, they're the most valuable images in the article. Let's try to keep them (or substitute better images if such are available). A lot of the other images in the article are either of limited relevance (the images of Earth's ocean floor), of limited interest (the diagrams of the interior models and magnetic field don't convey much information), or are based on speculation (the cryobot is not going to happen any time soon). So if we still have too many pictures, let's not toss the few that show the details of surface geology. WolfmanSF (talk) 05:32, 30 January 2008 (UTC)

thanks
very interesting. well done. kerfuffle (talk) 05:20, 26 February 2008 (UTC)

thank you all, editors, for this article! 98.199.206.122 (talk) 07:04, 26 February 2008 (UTC)
 * Thank you. Nice to know the article is helping people.  Serendi pod ous  09:05, 26 February 2008 (UTC)

Question:
If Europa were somehow warm enough would the Oxygen be breathable by us? —Preceding unsigned comment added by 165.155.110.74 (talk) 17:10, 26 February 2008 (UTC)
 * Too thin -- see the Atmosphere section.Fritter (talk) 19:23, 26 February 2008 (UTC)
 * If Europa were closer to the Sun, it would be gradually boiled away. As its surface were reduced first to ice and then to steam, it might have a thick atmosphere for a relatively brief time, geologically speaking, and during that time, disassociation would probably create a small amount of free oxygen in the atmosphere, but it wouldn't last. Europa just doesn't have enough gravity to hold on to its air. Eventually it would be reduced to a barren airless core.  Serendi pod ous  20:07, 26 February 2008 (UTC)

Isn't this Repetition? Opinion please
Europa is the sixth-nearest and fourth-largest moon of the planet Jupiter. Europa was discovered in 1610 by Galileo Galilei (and, some say, independently by Simon Marius), and named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete. It is the smallest of the four Galilean moons.Yyem (talk) 12:22, 28 February 2008 (UTC)
 * yeah, you're probably right. That sentence doesn't read well anyway.  Serendi pod ous  12:24, 28 February 2008 (UTC)

In Odyssey Two
Hi, I'm mildly surprised there's no mention of 2010: Odyssey Two. 2010 is definitely notable IMHO. --Kjoonlee 00:15, 8 March 2008 (UTC)


 * 2010 is mentioned more than once on Jupiter's moons in fiction, which is linked to at the bottom of the article. --Patteroast (talk) 00:47, 8 March 2008 (UTC)
 * Ah, thank you! :) --Kjoonlee 09:00, 8 March 2008 (UTC)

Pointless statement about mass
Isn't this rather an uninteresting fact: "its mass nonetheless significantly exceeds the combined mass of all moons in the Solar System smaller than itself"? Suggest we delete this. LarsHolmberg (talk) 20:36, 21 March 2008 (UTC)
 * "Uninteresting" is a fairly subjective assessment. Irrellevant to the article, inaccurate, out of date, these are reasons for deletion. But deleting a fact because it is "uninteresting" isn't really encyclopedic. There are many who would find this entire article uninteresting. Serendi pod  ous  09:16, 22 March 2008 (UTC)
 * Serendi, I like your atittude, really. You are open, have a good approach and accept critics. Keep up the good work, and thanks for a good job! Martín (sorry, not logged in)

Don't you mean 'Satellite'?
Isn't the correct term for a body orbiting any planet a 'satellite', not a 'moon'? Moon is the proper name of the satellite orbiting our planet, Earth. Thoughts on this? This correction would have to be made across many wikipedia entries. —Preceding unsigned comment added by 99.249.31.69 (talk) 21:43, 28 March 2008 (UTC)
 * Wikipedia uses "moon" as standard, presumably because "satellite" leaves open the question as to whether it is a natural or artificial satellite.  Serendi pod ous  23:46, 28 March 2008 (UTC)
 * When you refer to a 'moon' (lower-case) it means any natural satellite, while the 'Moon' (upper-case) is Earth's only moon. That's a pretty pretty standard usage as far as I've seen, and what Wikipedia uses. --Patteroast (talk) 02:16, 29 March 2008 (UTC)

Vandalism
the following text "do u know i love to go to Europa" in the section "extraterrestrial life on Europa" is a vandalism that I could not fix. It does not appear in the wikipedia editor neither it was found under emacs search (emacs search only found one know as a part of the word knows in the entire article ) please fix this and also please leave a message in my talk on how to find and fix these. I am totally at loss. Jeroje (talk) 00:56, 19 November 2008 (UTC)
 * It was probably removed between your loading of the page and you clicking 'edit', but still in your browsers cache when going back to the page. --Gerrit CUTEDH 23:40, 19 November 2008 (UTC)

Requested move

 * The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 

The result of the proposal was no consensus to move the page, as per the discussion below. Dekimasu よ! 00:28, 27 January 2009 (UTC)

Europa (moon) → Europa — It strikes me that the moon is by far the most recognizable meaning of the name "Europa" and probably qualifies as the WP:PRIMARYTOPIC. As such, it would make sense to give it the main page and move the current Europa page to "Europa (disambiguation)". — Dragons flight (talk) 00:14, 22 January 2009 (UTC)

Survey

 * Feel free to state your position on the renaming proposal by beginning a new line in this section with  or  , then sign your comment with  . Since polling is not a substitute for discussion, please explain your reasons, taking into account Wikipedia's naming conventions.


 * Oppose  Serendi pod ous  00:30, 22 January 2009 (UTC)


 * Oppose kwami (talk) 02:19, 22 January 2009 (UTC)


 * Oppose --Akhilleus (talk) 02:33, 22 January 2009 (UTC)
 * Comment. Would someone care to offer a reason? This is not a majority vote - decisions are made solely on the strength of the arguments given, and none have been offered. 199.125.109.126 (talk)
 * Oppose. There are many other things named Europa. Anthony Appleyard (talk) 06:16, 22 January 2009 (UTC)
 * Oppose - As Europa can refer to a number of things, and there is no obvious "primary topic" here. --DAJF (talk) 06:44, 22 January 2009 (UTC)
 * Oppose - if someone mentioned the word "Europa" to me, the moon wouldn't be among the first three things I thought of, let alone the first. - fchd (talk) 08:31, 22 January 2009 (UTC)
 * Oppose. I don't think it's been demonstrated that the moon is the clear primary topic, as is required by our disambiguation conventions. Although I agree that the first three comments above hold no weight in the conclusion of this discussion. Chris Cunningham (not at work) - talk 09:40, 22 January 2009 (UTC)
 * Oh, give me a break. The nominator hasn't supplied much than "I think this is the primary topic"--do the oppose voters the courtesy of assuming that their reason is "I think it's not the primary topic". Also, see Talk:Ganymede (moon). --Akhilleus (talk) 12:34, 22 January 2009 (UTC)
 * I posted my comment in the discussion section.  Serendi pod ous  12:43, 22 January 2009 (UTC)


 * Support per new stats which indicate that the moon is a clear primary use per page views; that's not a good measure for many things on Wikipedia, but our naming conventions are based on little except for popularity and it does appear that this is by far the most popular Europa page visited. As such, we should move it to the root article to decrease the required number of hops required to view it from a search for that term. Chris Cunningham (not at work) - talk 14:25, 22 January 2009 (UTC)
 * It is not correct to say that our naming conventions are based on little except for popularity. Traffic statistics are only one indication to consider (and IMO one of the weakest in that it can result in a navel-gazing reinforcement of WP:Systemic bias). Google and other search engine statistics are another type of indication (especially the news, books and scholar sections). Another indication is whether other general purpose reference works treat one of the topics as primary. older ≠ wiser 13:05, 23 January 2009 (UTC)
 * Oppose per new stats, which omit the largest other meaning of Europa, and are in any case insufficient. The reason to have a page at primary usage is to assist an overwhelming majority of readers who want to go there by making them click only once, at the price of making everybody else click three times (to Europa, to the dab page, and where they actually want to go). This proposal would have us assist a minority at the expense of everybody else.  Septentrionalis PMAnderson 20:09, 22 January 2009 (UTC)
 * Oppose per stats below and because the use of (moon) in the article name seems to be standard for satellites of the solar system. --Volcanopele (talk) 20:28, 22 January 2009 (UTC)
 * That is probably because many or most of the moons in our solar system are named for mythological characters and therefore need disambiguation. •Life of Riley (talk) 04:56, 23 January 2009 (UTC)


 * Oppose. Europa, the mythological character, is ultimately the eponym of all of the other usages listed here. If any topic were to be the primary, it should be that character. •Life of Riley (talk) 04:56, 23 January 2009 (UTC)
 * Oppose. Primary topic requires considerably more than even a simple majority of traffic. older ≠ wiser 11:27, 23 January 2009 (UTC)
 * Oppose - The mythological and geographical uses of the name are quite significant enough to make this move counter-productive. AlexTiefling (talk) 16:56, 23 January 2009 (UTC)

Discussion

 * Any additional comments:

"Europa" is the name of Europe in every European language except English. I think Europe probably has a higher recognition level than a moon of Jupiter. Plus all moons on Wikipedia have "(moon)" as a disambig.  Serendi pod ous  00:30, 22 January 2009 (UTC)


 * If this were an encyclopedia written in any language but English, I'd care about your first point, but frankly it seems silly to me to argue English naming conventions based on foreign languages. Dragons flight (talk) 00:38, 22 January 2009 (UTC)
 * People who speak English are fairly likely to encounter the alternate name of Europe, particularly if, like myself, they happen to live there.  Serendi pod ous  00:40, 22 January 2009 (UTC)
 * Easily handled by a note at the top of the article (if people agree it is necessary, which I'd still need convincing). But the current Europa is no more about Europe than this one is, so I still don't see the point of that line of argument.  Either way someone entering "Europa" while looking for Europe would be in the wrong place and still needs to be directed elsewhere, so I can't see how it makes any difference to this naming discussion.  Dragons flight (talk) 00:55, 22 January 2009 (UTC)


 * On the other point, I think Ganymede and possible others should qualify for primary topic status too. (And there is no question about people being confused looking for Europe when typing Ganymede ;-).  Dragons flight (talk) 00:55, 22 January 2009 (UTC)

And how do we decide which moons get top billing? And after we decide, how do we remember which is which? It's easier just to keep '(moon)' after all of them, just as we indicate ethnicities with 'people' and languages with 'language'. kwami (talk) 02:23, 22 January 2009 (UTC)


 * By actually following WP:PRIMARYTOPIC to decide which ones are in fact the primary topic. There is no naming convention that requires using the tag (moon), and that would be counterproductive if most people are in fact looking for the moon.  The comparison to "people" vs. "language" is not a comparable situation, since "X people" and "X language" are generally both of comparable significance, so PRIMARYTOPIC wouldn't apply.  Dragons flight (talk) 02:35, 22 January 2009 (UTC)


 * Have you any evidence to suggest that there is a clear primary topic here? I agree with the general points you're making about disambiguation, but not with the assertion that we've got an obvious primary topic here which would warrant moving the dab page off to (disambiguation). Chris Cunningham (not at work) - talk 09:42, 22 January 2009 (UTC)


 * Having an obligatory "(moon)" makes no sense if the moon is clearly the primary meaning of the term. And no, we don't use obligatory "people" (see Poles, Croats, Italians) or "language" (Latin, Esperanto, Scottish Gaelic) either. Jafeluv (talk) 12:55, 23 January 2009 (UTC)


 * You'll find that in several languages - French springs to mind - the word for 'Europe' is not 'Europa'. (In French, it is 'Europe'.) AlexTiefling (talk) 16:56, 23 January 2009 (UTC)

Stats
Apparently what I find blindingly obvious, other people want numbers for. Well, okay. Of the various "Europa" topics, the moon received 4.5 3 times as much traffic as any other term in December, and ~45% ~40% of the traffic to all Europa topics. For me, that's a more than large enough distinction to give the moon primacy. Stats based on http://stats.grok.se/. Dragons flight (talk) 13:54, 22 January 2009 (UTC)


 * Note: I screwed up the table the first time, by omitting (mythology). Sorry about that, see below.  Dragons flight (talk) 20:23, 22 January 2009 (UTC)


 * And where's Europa (mythology)? This has around 11k page views. —  3 2 4 7    (talk) 20:04, 22 January 2009 (UTC)
 * (after ec, new post) I was checking the same thing: 11,147, if somebody wants to recalculate the table.) Which reduces this page to around 40% of all views; primary usage should be around twice that. Septentrionalis PMAnderson 20:15, 22 January 2009 (UTC)
 * Fark. I'm guessing I skipped due to not being bulleted in the list.  I'll fix the table.  Genuinely sorry about that.  Dragons flight (talk) 20:17, 22 January 2009 (UTC)
 * So, you read the sciences rather than the humanities. (Anyone who read both would have been surprised to find Europa and the Bull not in the first two here, and checked.) No problem; but many who read the humanities rather than the sciences think of Europa (mythology) as the obvious primary meaning, which is why neither should be. Septentrionalis PMAnderson 20:36, 22 January 2009 (UTC)
 * Europa League (the new name for the UEFA Cup picks up another 500+ hits as well. I think 39% is way too low for it to be considered a definite primary meaning. Sorry. - fchd (talk) 21:23, 22 January 2009 (UTC)
 * Comment. I am not aware of any "standard for primary usage" as in "primary usage should be around twice that". My own "standard for primary usage" is that the primary usage have 2 to 3 times as many hits as the second highest, but no where is any standard written down. The guidelines only indicate "significantly more". Well in science, 0.000001% more can be "significantly more" if it can be clearly delineated. I also would never use percentage of all hits as a criteria, but only ratio of the first place to the second place, because the way exponentials tail off you can still have one primary topic, and yet have far less than half the total. 199.125.109.102 (talk) 02:10, 25 January 2009 (UTC)
 * The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Snowball Earth
Does anyone know of how they compare I would be very interested to know. And I think the comparison shouts life. If think this is junk just erase it don't mark my profile just erase. Nate Riley 14:38, 21 March 2009 (UTC)
 * On Snowball Earth, photosynthesis was still possible even under the ice, because deep ice becomes almost transparent. However, Europa is much farther from the Sun, so photosynthesis is probably impossible (assuming, of course, that there is life). Also, Earth's snowball period was ended by increased volcanic activity dumping huge amounts of CO2 into the atmosphere. Since Europa's ocean, if it has one, is far deeper than Earth's (perhaps 60 miles), any volcanic activity would be submarine.  Serendi pod ous  18:13, 21 March 2009 (UTC)
 * This is untrue. "deep ice" does not become transparent, and in the most extreme versions of snowball earth, in which the planet is glaciated to the equator, photosynthesis would likely be limited only to those few mountainous/volcanic regions which penetrate the ice.  Photosynthesis is possible, but not particularly productive, at the light levels Europa sees, but the surface is bathed in ionizing radiation, and at even moderate depths within the ice would become impossible.  However, if there is life on Europa, it is potentially surviving on the same energy source as the majority of the life on Earth which would have survived any serious snowball event: chemical gradients driven by hydrothermal systems, so there is a very reasonable parallel to draw.  Zaneselvans (talk) 07:09, 17 June 2009 (UTC)

Copernicus
I removed the note about the Copernican system because it is not included in this article's sister articles Io, Ganymede or Callisto. It is included hower in Gallilean moons. The ref information I moved there. Str1977 (talk) 16:37, 30 March 2009 (UTC)
 * OK, fair enough.  Serendi pod ous  16:45, 30 March 2009 (UTC)
 * Thanks for understanding and sorry that I didn't provide my reasons to begin with. Str1977 (talk) 17:28, 30 March 2009 (UTC)

In orbit around Europa?
If Europa is less massive than the Earth's moon, is it possible for an artificial satellite to be placed in a very long-lived orbit around Europa? Aren't there too many satellites around Jupiter for artificial satellites to remain in orbit around Europa for long? I have been told that the best that can be done, is a couple weeks at best. I get a little confused by the idea of long-lived orbits, and have been told that all orbits are ultimately unstable. But is it possible for a satellite to be placed in an orbit that lasts for more than 10 years? 216.99.201.35 (talk) 03:49, 13 September 2009 (UTC)216.99.201.35 (talk) 03:52, 13 September 2009 (UTC)

Was Europa named "Jupiter II" because of its position?
The Voyager probes discovered three more inner satellites in 1979, so Europa is now considered Jupiter's sixth satellite, though it is still sometimes referred to as Jupiter II.; I do not think this is correctly put. If Europa was named initially "Jupiter II" because they thought it to be the second closest satellite to Jupiter, then why was this name retained after the discovery of the other more inner satellites? Does "II" not simply refer to the fact that Europa was the second moon to be discovered? The Wiki ghost (talk) 09:47, 30 April 2010 (UTC)
 * Europa's designation as "II" does refer to being the second closest satellite, and it was retained because repeatedly changing the designation of a moon doesn't achieve much besides confusion. This is explained at Titan (moon); Titan did in fact have its designation changed a couple times because inner satellites were discovered, though it was soon frozen at VI. It's not entirely clear whether or not Europa was the second moon to be discovered, as you say (but most probably not); the order of discovery is something of a mess. See the relevant discussion at Talk:Ganymede (moon). Sideways713 (talk) 20:04, 5 August 2010 (UTC)

Source on Smoothness
In the summary, second paragraph, it mentions that Europa is: "...one of the smoothest in the Solar System."

Can anyone find a source on this? Thanks. --65.44.114.33 (talk) 22:03, 4 May 2010 (UTC)
 * Try source 29  Serendi pod ous  22:13, 4 May 2010 (UTC)

Life on Europa
If there is life on Europa it will not be more advanced then the human race. If they were advanced, they'd have radio satellites. No radio satellites = no advanced life. —Preceding unsigned comment added by 72.192.157.57 (talk) 03:20, 13 December 2010 (UTC)
 * In order to have radio satellites, you have to have knowledge that there is something to put radio satellites into. There's no reason to assume any advanced life lurking on the ocean floor of Europa would even have a concept of space, let alone spacefaring.  Serendi pod ous  10:29, 13 December 2010 (UTC)

There is a bigger "danger" if somebody will ever discover the life on Europa; several religious, theological groups will claim "it came from planet Earth"; they will put planet Earth into the center of the whole solar system, universe and claim that "everything came from Earth, according to their Abrahamic god", they will "prove" their theory with Panspermia; this is like the ethnocentric claim about Biblical historians who claim that "all people came from the Middle east, Israel because "first" human civilizations started there after the "Creation"... The biological question: did all animals, planets, fungi, eucaryotes, prokaryotes really evolve on planet Earth from some "common living prokaryote"? I think that humans will more or less figure out (and confirm) that we have "aliens" on that planet, which evolved on totally different worlds, than on our Earth... perhaps several of them (like are also chemotrophic organisms)came from "outside", from icy moons like Europa or Titan...

Potential for Extraterrestrial Life
In this chunk of info, there is/was a bunch of crap about chemosynthesis and discovering tube worms off the Galapagos. This really needs to be truncated down to barely more than a referral to another page. This page is about Europa chiefly, and it jumps a little too far off topic despite how interesting it may be. —Preceding unsigned comment added by 75.149.166.33 (talk) 10:18, 4 March 2011 (UTC)
 * The information is very important, because it shows how life could exist on Europa, despite the inhospitable environment.  Serendi <sup style="color:#bb0000;">pod ous  10:21, 4 March 2011 (UTC)
 * However, much of this info doesn't apply distinctly to Europa. In particular, the three middle paragraphs and pictures. It is largely about how life could exist in any extraterrestrial ocean (not even necessarily subsurface, but that's all we're concerned about in the solar system), and could/should be on the pages for several other objects, notably Ganymede. I.e., it is a digression. A reference to a section in a separate exo-life page (the astrobiology page seems the likely candidate), with this section just describing why Europa may be particularly suitable to that type of life: tidal heating, rocky core, O2 from radiation on ice, etc. Tbayboy (talk) 18:13, 4 March 2011 (UTC)
 * This historical information is vital context; you can't just say that Europa's subsurface ocean could support life without sunlight and yet not explain why.  Serendi <sup style="color:#bb0000;">pod ous  20:33, 4 March 2011 (UTC)
 * We're not suggesting that. See "referral to another page" above, and my astrobiology suggestion. For example, the page on tigers doesn't have to explain the details of what it means to be a mammal, it just links to it. Similarly, the Europa page doesn't have to explain the details of hydrothermal vent life, just link to it; this page need only explain why Europa might have such life. Tbayboy (talk) 23:58, 4 March 2011 (UTC)

EAS: Europa Avoidance Syndrome
There should be a section on how the Mars missions are seen as competitive (for funding) with a series of cancelled Europa missions (Europa, a moon of Jupiter, that has a confirmed saltwater ocean, is considered the most promising location for extraterrestrial life in the solar system). Yet the resulting funding "turf wars" have sidelined Europa surface exploration for years.

Ditto for Saturns' moon Encaladus, which has another confirmed saltwater ocean. Most resources go to Mars, while the ocean moons languish.

The funding politics, and controversies related to this, are certainly worth a section in the article.

64.134.236.20 (talk) 20:29, 1 December 2011 (UTC)
 * As I know there is a separate Mars exploration program. So, they do not directly compete. Ruslik_ Zero 10:04, 2 December 2011 (UTC)


 * Oh yes they do compete with each other! The space program funding pool is very limited now--


 * And so there is absolutely competition for limited funding dollars between the existing Mars program and potential life detecting missions to the ocean moons for the small pool of resources that are at play.


 * Not only that, there is a sense of very keen competition about who gets to claim the first discovery of extraterrestrial life--


 * The Mars mission, being well established, has a far more powerful "lobby" with which to acquire congressional funding, both within NASA, and directly from congress (congressional NASA funding implicitly earmarked for the Mars mission).


 * Even though the confirmed ocean moons, Europa and Enceladus are far more likely to harbor life than Mars; scientists who want to make the ocean moons a higher priority are far less organized and have far, far, far less funding than the Mars mission does.


 * The Mars mission is like an 800 pound gorilla-- and the science interests that want to send life-detecting probes directly to the ocean moons (now, not in 30 years), are like the world's smallest monkey-- the pygmy marmoset, which weighs only 3.5 ounces. Guess which side is winning the battle for funding...


 * 2602:306:BDA0:97A0:466D:57FF:FE90:AC45 (talk) 17:55, 9 July 2014 (UTC)


 * Perhaps they have had their instructions: "ALL THESE WORLDS ARE YOURS—EXCEPT EUROPA. ATTEMPT NO LANDING THERE".
 * By the way, I'm not a fan of "In popular culture" mentions, but this quote was from Arthur C. Clarke's 2010: Odyssey Two. Kortoso (talk) 18:27, 27 October 2015 (UTC)

We're missing something...
How did Europa form? 68.173.113.106 (talk) 03:25, 31 March 2012 (UTC)
 * Try it now. :)  Serendi <sup style="color:#bb0000;">pod ous  07:30, 31 March 2012 (UTC)


 * Goddidit! :-)  BatteryIncluded (talk) 12:16, 18 October 2012 (UTC)

This page scared me
Did anyone else scroll down this page slowly and then freaked out by the rotating orbit GIF? I thought it was a bug or something at the bottom of my screen! — Preceding unsigned comment added by 24.212.199.46 (talk) 02:46, 9 August 2013 (UTC)

Surface Temperature is Incorrect
The surface temperature is listed as -50 K. Since 0 K corresponds to absolute zero, this cannot be correct. The Johnston Archive suggests ~85 K ( http://www.johnstonsarchive.net/astro/europa.html ). If anyone can confirm or improve this with a more vetted source, that would be helpful. — Preceding unsigned comment added by 72.183.104.134 (talk) 04:17, 22 October 2013 (UTC)


 * That's not -50 K that's ~50 K. —  Reatlas  (talk)  05:34, 22 October 2013 (UTC)


 * I'd suggest replacing the "~" with the word "about".Kortoso (talk) 18:24, 27 October 2015 (UTC)

Organic material ?? Or organic compounds
There is a big difference. I'd be very suprised if there was organic material on the surface ...--EvenGreenerFish (talk) 12:51, 15 December 2013 (UTC) '''
 * I understand your concern - however - seems the phrase "organic material" is found "4" times in the original cited NASA reference; "organic compound" (or even the word "compound") is found "0" times (ie, not found at all) - please see => < ref name="NASA-20131211"> - based on this original cited NASA ref, edited back from "organic compound" to =>'''""organic material" (according to NASA)"
 * hope this is ok - please let me know if otherwise of course - Enjoy! :) Drbogdan (talk) 14:13, 15 December 2013 (UTC)

Semi-protected edit request on 4 February 2014
i know something wrong

Hnndcfgn (talk) 18:54, 4 February 2014 (UTC) Furthermore, you have not cited any reliable sources to back up your request, without which no information should be added to any article. - Arjayay (talk) 19:38, 4 February 2014 (UTC)
 * OK, well what is it?  Serendi <sup style="color:#bb0000;">pod ous  19:04, 4 February 2014 (UTC)
 * Red information icon with gradient background.svg Not done: You have made no edit request in the form "Please replace XXX with YYY" or "Please add ZZZ between PPP and QQQ", so it is unclear what you want added or altered.

Life in Space
Of possible interest -- In any case - Enjoy! :) Drbogdan (talk) 14:19, 11 February 2015 (UTC)
 * Finding => NASA Workshop on the Potential for Finding Life in a Europa Plume (02/18/2015)
 * Spreading => NASA Workshop on Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions (03/24/2015)

This was one of the first moons discovered ... why is that not mentioned in the opening para ?
Every time this is mentioned in the lede, someone edits it out. Some kind of conspiracy ?? It is extremely significant, that after our moon, it (with Io) was the first to be found ! --EvenGreenerFish (talk) 12:42, 26 March 2015 (UTC)
 * Not really. Suppose you are trying to discover traffic lights. On 7 January, you see a patch of green in the distance that cyclically changes through amber and red before returning to green. Aha! Traffic light discovery, you think. But the next day you conduct close-up observations, and you find that they were actually two adjacent synchronized traffic lights: let's call them "Signal" and "Stoppy". Since you only recognized the traffic lights as individual entities on 8 January, it doesn't make sense to call 7 January the discovery date for either Signal or Stoppy alone. This is essentially what happened with Io and Europa: on 7 January 1610, they were observed together as one single point of light, and were only seen to be separate the next day. Additionally, Ganymede and Callisto were seen unambiguously on 7 January 1610, so Io and Europa alone weren't the first to be found. Double sharp (talk) 12:56, 26 March 2015 (UTC)


 * So tell me then. What other moon was found before them ..... and after The Moon ??????  I don't really care WHEN they were discovered.  All I care about is that they were the first moons found to orbit another planet !!! Not even the Galilean moons article mentions this.  Basically I want to know this and what it was named for. Instead we get a bunch of fluff about flybys in the 70s. --EvenGreenerFish (talk) 13:02, 26 March 2015 (UTC)
 * Because, as Double Sharp points out, they were not really discovered on 7-1-1610, they are not the first ones discovered after the Moon. Ganymede and Callisto are. A third point of light was seen that day, but it cannot be said to be either Europa or Io. --JorisvS (talk) 13:57, 26 March 2015 (UTC)
 * Quite. Here's the chronology of the first few moons discovered, presented in a list.
 * Moon: Sometime in prehistory, when one night, someone decided to look up
 * Ganymede and Callisto: 7 January 1610. A third point of light was seen, but it cannot really be said to be one of Europa or Io.
 * Europa and Io: 8 January 1610.
 * Titan: 25 March 1655
 * ...etc.
 * And as for what Io and Europa were named for: it's already in the Io article, while I added it to the lede of Europa's. Double sharp (talk) 14:27, 26 March 2015‎ (UTC)

Merge discussion at Talk:Life on Europa
There is an ongoing discussion at Talk:Life on Europa about whether to merge Life on Europa into Europa (moon). Any reasoned comments would be helpful. A2soup (talk) 15:16, 16 August 2015 (UTC)

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Requested move 2 October 2015
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 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section. 

The result of the move request was: Not moved. Natg 19 (talk) 19:53, 9 October 2015 (UTC)

– Europa the moon is FAR more of the primary topic than anything else named Europa. People know about an icy moon of Jupiter with water beneath its surface. They may not know its NAME, but they know it's there. Not many people know anything about Europa the mythological figure. The moon is clearly the primary topic here, so the Europa page, currently a disambig page, should be moved to Europa (disambiguation), with this page moved to Europa. DN-boards1 (talk) 22:17, 2 October 2015 (UTC)
 * Europa (moon) → Europa
 * Europa → Europa (disambiguation)


 * Oppose If there was only one or two articles called Europa, I'd agree, but there are dozens. Keeping the current setup allows for easy indentification of incorrect incoming links.  Lugnuts  Dick Laurent is dead 10:09, 3 October 2015 (UTC)
 * Oppose. UEFA Europa League is not related to the moon. 178.95.189.176 (talk) 19:00, 3 October 2015 (UTC)
 * Oppose - There are many articles called Europa and arguing which is the 'primary' is pointless. BatteryIncluded (talk) 19:28, 3 October 2015 (UTC)
 * Oppose per the others Johnbod (talk) 22:12, 3 October 2015 (UTC)


 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Thin ice/thick ice debate
The following paper, Empirical constraints on the salinity of the europan ocean and implications for a thin ice shell, by Kevin Hand and Christopher Chyba, uses magnetic field data from Galileo to put a constraint on subsurface ocean salinity. They conclude that a) only a relatively thin shell of ice (< 15 km, with a best fit at 4 km) can fit the data and b) only very high (magnesium sulfate) salinity can readily explain the very high amplitude response (0.97 +/ 0.02) observed by Galileo. In particular, adding a solid conducting core and mantle to the model has no appreciable effect compared to that of the ocean itself.

This should probably be worked into the article, which currently presents the thin ice/thick ice debate largely in terms of surface feature analysis. Eniagrom (talk) 13:49, 18 July 2016 (UTC)
 * A 2017 paper - http://lasp.colorado.edu/home/mop/files/2018/07/571-586-with-Images.pdf 50.111.27.136 (talk) 16:19, 31 August 2019 (UTC)

New Information on "spewing water jets
This article from BBC was posted today in regards to the new discovery of "water plumes" on Europa. Would it be worth adding this information to the page, or does it fall under WP:RECENT? Let me know what you think. Cheers Comatmebro  User talk:Comatmebro 23:46, 26 September 2016 (UTC)
 * It is worth a mention. But that article is not so definite! Graeme Bartlett (talk) 00:53, 27 September 2016 (UTC)
 * It has been added today, as an "additional evidence". Cheers, BatteryIncluded (talk) 02:10, 27 September 2016 (UTC)

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 * astrobio link is dead, it looks like that site no longer hosts the content. Graeme Bartlett (talk) 08:36, 20 May 2017 (UTC)

Habitability claims out of date
The article's section on habitability potential currently says that "The energy from tidal flexing could never support an ecosystem in Europa's ocean as large and diverse as the photosynthesis-based ecosystem on Earth's surface." But the citation is from 1999, and more recent studies have questioned it. particularly those showing that subduction of oxygen-rich ice from the surface could lead to high oxygen levels in the ocean below. I think this should be mentioned.  Serendi <sup style="color:#bb0000;">pod ous  21:20, 31 July 2017 (UTC)


 * Agreed, it's out of date. Also there's the new research, that it could have as much hydrogen per square centimeter as Earth's ocean, even though there'd be less energy available for hydrothermal vents, due to cracks that would appear in its core as it cools down.


 * and and [https://www.jpl.nasa.gov/news/news.php?feature=6514


 * "According to Vance, researchers previously speculated that volcanism is paramount for creating a habitable environment in Europa's ocean. If such activity is not occurring in its rocky interior, the thinking goes, the large flux of oxidants from the surface would make the ocean too acidic, and toxic, for life. "But actually, if the rock is cold, it's easier to fracture. This allows for a huge amount of hydrogen to be produced by serpentinization that would balance the oxidants in a ratio comparable to that in Earth's oceans," he said."


 * "My modest thought about what kind of life might be at Europa involves the kinds of things that we see at heads of thermal vents [on Earth], mainly microorganisms,"But in my bolder moments I wonder if Europa could have the kind of vigorous biosphere that Earth has that supports larger forms of life,"


 * There's a bit of a mystery with the hydrogen peroxide that they found less than expected for that oxygen hypothesis, which suggested an oxygen poor ocean after all, but on the other hand there is evidence of more oxygen in the ice of the crust than expected which could be compatible with it being oxygen rich. This paper however is from 2013.


 * "Compared to models for seafloor production of reductants, such as methane and hydrogen sulfide, which yield ~3 × 109 moles per year delivered to the ocean, it appears that our new results for peroxide on Europa could lead to an ocean limited by oxidant availability. This conclusion also depends strongly on the global geographic distribution of O2, which may have concentrations significantly larger than peroxide"


 * I think it is fair to say the jury is out on this one so far, from what I've read. Robert Walker (talk) 00:03, 11 August 2017 (UTC)

Smoothness claim should be qualified
This is the statement "Europa has the smoothest surface of any known solid object in the Solar System"

That's true as seen from the distance. Nothing else is as smooth and round by way of the solid objects, because its craters relax into the ice and the surface is very young. But close up, on the meter scale, it is very rough indeed at every scale observed, far rougher than, say, Mars.

From an article in Scientific American, Feb. 17, 2017:


 * “Although mission planners have yet to map Europa at very high resolution, the lower-resolution images they have already seen show a topography rugged enough to give them nightmares, says Britney Schmidt, a planetary scientist at Georgia Tech and study co-author. 'Icy surfaces on Earth are incredibly complex, and Europa is rough on every scale we’ve ever observed it, so finding a flat spot might be impossible,' she says. 'It’s hard not to be worried about that. Mars has been difficult for us—and it’s way flatter than Europa.' ”

Robert Walker (talk) 00:10, 11 August 2017 (UTC)
 * However, Europa has no 'mountains' - Mars does. Europa has cracks in the ice where jagged edges do indeed rise for many meters, but I'd take some exception with this particular comment/astronomer over the overwhelming majority who state otherwise?
 * Please sign your ^ posts. The comment about mountains is completely irrelevant. Which astronomers say the surface is flat like a billiard ball? Every informed scientific statement - and painting - I've seen of Europa's surface is rough like the Arctic Ocean where ice sheets collide and push up the ice. You certainly would be hard-pressed to land any rough-field fighter jet on it - there just isn't any place (supposedly) that doesn't have bumps etc. The OP is correct. 50.111.44.55 (talk) 10:03, 17 June 2021 (UTC)

External links modified
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External links modified (February 2018)
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External links modified (February 2018)
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surface radiation
The type of radiation and the various strengths of it (alpha particles, beta, neutron, EM) should be added to the article. I think I've read some fairly reasonable predictions of this based on the observed data. Does anyone have an RS? 50.111.3.150 (talk) 22:14, 24 August 2019 (UTC)
 * Of the four mentioned radiation types only electron (beta) component is significant on Europa. Ruslik_ Zero 12:46, 25 August 2019 (UTC)
 * so, a Reliable Source showing the average strengths of the various types of radiation at the surface should be readily available and stated in the article? — Preceding unsigned comment added by 104.169.16.163 (talk) 08:25, 31 August 2019 (UTC)

habitability thing
would creating a new article called Life on Europa be a good idea? idk :VAzpineapple (talk) 03:45, 19 September 2020 (UTC)
 * No. There would be almost zero RS information on something that is pure, unadulterated wishful thinking/speculation.50.111.24.158 (talk) 00:58, 15 November 2020 (UTC)