Talk:Enceladus

Template:Vital article

Lead section - tagged

I tagged the lead section for a rewrite because:

• Water plumes have 3 separate entries just within the introduction.
• Water is mentioned about 14 times.
• Lead section should ideally contain no more than four paragraphs and be carefully sourced as appropriate.

Thank you, BatteryIncluded (talk) 16:43, 4 April 2014 (UTC)

Agreed (except sources are optional in material is referenced in the body of the article) and will add that it does a poor job of summarizing anything in the article except for the possible presence of water. --ThaddeusB (talk) 19:37, 4 April 2014 (UTC)

Rewrite

Hi,

How 'bout this for the intro paragraphs? I tried to get rid of stuff thats old scientific opinion and integrate todays new announcements better. Please add your input and what else should be changed. Thanks Reedman72 20:57, 4 April 2014 (UTC)

Enceladus is the sixth-largest moon of Saturn. It was discovered in 1789 by William Herschel.Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface. The Voyagers showed that the diameter of Enceladus is only 500 kilometers (310 mi), about a tenth of that of Saturn's largest moon, Titan, and that it reflects almost all of the sunlight that strikes it. Voyager 1 found that Enceladus orbited in the densest part of Saturn's diffuse E ring, indicating a possible association between the two, while Voyager 2 revealed that despite the moon's small size, it had a wide range of terrains ranging from old, heavily cratered surfaces to young, tectonically deformed terrain, with some regions with surface ages as young as 100 million years old.

In 2005 the Cassini spacecraft performed several close flybys of Enceladus, revealing the moon's surface and environment in greater detail. In particular, the probe discovered a water-rich plume venting from the moon's south polar region. This discovery, along with the presence of escaping internal heat and very few (if any) impact craters in the south polar region, shows that Enceladus is geologically active today. Moons in the extensive satellite systems of gas giants often become trapped in orbital resonances that lead to forced libration or orbital eccentricity; proximity to Saturn can then lead to tidal heating of Enceladus's interior, offering a possible explanation for the activity.

On April 3 2014, NASA reported that evidence for a large underground ocean of liquid water on Enceladus had been found by the Cassini spacecraft. Cryovolcanoes at the south pole shoot large jets of water vapor, other volatiles, and some solid particles like [[NaCl] crystals and ice particles into space, totaling approximately 200 kg per second. Some of this water falls back onto the moon as "snow", some of it adds to Saturn's rings, and some of it reaches Saturn. The discovery of the plume has added further weight to the argument that material released from Enceladus is the source of the E ring.

Because of the presence water at or near the surface, Enceladus may be one of the best places to look for extraterrestrial life. By contrast, the water thought to be on Jupiter's moon Europa is locked under a very thick layer of surface ice, though recent evidence may show that Europa also experiences water plumes.Analysis of the outgassing suggests that it originates from a body of subsurface liquid water, which along with the unique chemistry found in the plume, has fueled speculations that Enceladus may be important in the study of astrobiology. According to the scientists at Nasa, evidence of an underground ocean suggests that Enceladus is one of the most likely places in the Solar System to "host microbial life".

--— Preceding unsigned comment added by Reedman72 (talk • contribs)

References

Looks good. I say go for it - it is certainly better than what we have now. I would drop the last sentence as it is largely redundant in some should be a brief summary (it can and should be included in the body). There are a few other tweaks I might make, but for copyright reasons it would be cleaner if you paste your text into the article and then I edit it rather than making the tweaks here. --ThaddeusB (talk) 22:52, 4 April 2014 (UTC)

Ok, thanks man. It has been a featured article for a long time ('06 I think) and it has kinda lost some of its "featuredness" and I hope to help it out. Reedman72 23:08, 4 April 2014 (UTC) — Preceding unsigned comment added by Reedman72 (talk • contribs)

Glad to hear it. I was actually going to nominate it to be improved or delisted as it is definitely not up to current FA standards. The lead was the worst problem - I will have a list of a few other later. --ThaddeusB (talk) 23:59, 4 April 2014 (UTC)

Yes a list would help very much. I'd rather improve it than have to delist it but I think the sectioning is kinda messy. Reedman72 00:07, 5 April 2014 (UTC) — Preceding unsigned comment added by Reedman72 (talk • contribs)

Holy smokes! You guys are busy! The intro looks very good now. And also thanks to user 79.67.241.229 for his relentless energy fixing the references throughout Wikipedia. Thank you all. Cheers, BatteryIncluded (talk) 13:42, 5 April 2014 (UTC)

Major reorganization needed

I can't do this myself as I am not intimately familiar with the article; however, right now the "Characteristics" section is largely written in chronological order, and needs to be regrouped into topical order. You can't have two sections on a subsurface ocean, for instance. Serendi^podous 05:54, 5 April 2014 (UTC)

I have not read the whole article yet but I did notice, and agree, that the subsurface ocean entries should be coalesced to eliminate repetition. Same with its habitability potential. Cheers, BatteryIncluded (talk) 21:07, 5 April 2014 (UTC)

The first thing i'm doing is taking orbit out of characteristics, im just gonna go ahead with this one. Im taking a cue from Europa it has it that way. Thanks Reedman72 02:15, 6 April 2014 (UTC) — Preceding unsigned comment added by Reedman72 (talk • contribs)

"Tidal heating" section

This is one of many article adjustments coming: Other article sections dismiss tidal heating AND a subsurface ocean at equilibrium, but this section ends with "tidal heating on Enceladus may account entirely for a subsurface ocean at equilibrium". If tidal heating is an old displaced hypothesis, it must be deleted, or presented with a reduced importance weight, or mentioned briefly only for historical context. Need to read the research in a chronological context, determine the present model of 1) hydrostatic (dis)equilibrium; 2) the most likely heat source, and adjust this section/article accordingly. Cheers, BatteryIncluded (talk) 17:47, 6 April 2014 (UTC)

Pre-FA review comments

This article is currently not up to current feature article standards. If not improved, I intended to send it to WP:FAR for review. Here is a list of some things which need fixed:

• There are a number of old comments on this talk page that say such-and-such is confusing or inaccurate that were never answered. These need reviewed and addressed where appropriate.
• BatteryIncluded has just tagged several sentences/sections that need attention.
• As noted above, the article is repetitive and/or poorly organized in the "physical characteristics" subsections.
• Eyeballing it, about 20% of the article is unreferenced. All but the most obvious facts should be cited in a FA.
• The list of Cassini flybys is out of date.
• The date formatting (in particular in references) in inconsistent. The original authors appear to have used "January 1, 1900" type dates, so all dates should be converted to that format (no 1900-01-01 or 1 January 1900 dates).

• Don't agree - dates should be 1900-01-01 format, since at least 95% of them already are - at this stage, it doesn't matter what the original authors did, that is ancient history. hamiltonstone (talk) 02:10, 30 April 2014 (UTC)

• Reference formatting is inconsistent, including some refs with bare URLs. The easiest way to fix is to convert all refs to cite news/cite journal/cite book/etc. templates.
• The number of external links is excessive and should be trimmed.

That is all for now, ThaddeusB (talk) 18:46, 6 April 2014 (UTC)

My biggest problems with it are how the subsurface ocean, now being official, is referred to as possible. Also i have reed that its discovery has something to do with its high albedo making it possible to see something a few hundred km wide millions of miles a way in the 18th century. Reedman72 (talk) 21:40, 6 April 2014 (UTC)

I agree with Reedman; That is one typical example of the kind of overhaul it needs. My impression so far of this article is that new discoveries were entered as they happened, but the article was not updated as a whole. There is a chronological structure to it rather than currently known facts, and almost every entry claims to be the latest. From the scientific perspective, it needs a thorough review to update the whole article, not just enter new data. I seems to me some important sentences need to be referenced and -unfortunately- most entries may need to be verified against the cited reference AND, further, find out if they are still current hypotheses. Not a quick fix for a single editor, as this requires of commitment to read the references and use them in the correct context. Cheers, BatteryIncluded (talk) 22:48, 6 April 2014 (UTC)

So, the article saw significant improvements during the first half of April, but there are definitely still some problems. It is now well organized, but there still seems to be significant chunks of unreferenced text. I realize that it isn't a quick fix to verify the info is still current and reference it, but there haven't been any edits in 10 days or so. As such, I am wondering if there is still interest in improving the article? --ThaddeusB (talk) 04:34, 26 April 2014 (UTC)

@ ThaddeusB, can you please mark the statements or sections you think need more references? I will make the time to look them up. Thank you. --BatteryIncluded (talk) 15:51, 26 April 2014 (UTC)

I have added cn tags to some places that I think need references. Some statements may be OR or editorializing, and some may just need the previous reference use extended. I will also complain about some references. The Herschel, W. (1790) reference almost certainly will have online readable text and so should be linked. Many other web references should state the date and publisher. A question: should journal names be linked? Or does this just cause confusion for where to click to read the reference? Graeme Bartlett (talk) 08:56, 27 April 2014 (UTC)

I added the best [missing] references I was able to find and read. I still have to go over the whole text and verify the older references support the inline citation. Also, I will let someone else cleanup all the references' format. Cheers, - BatteryIncluded (talk) 02:24, 28 April 2014 (UTC)

Is anyone working on the section tagged for update Enceladus#Atmosphere? DrKay (talk) 19:30, 20 November 2015 (UTC)

Is it 5th or 6th largest.

According to our article on the moons of saturn its both sixth most massive and most voluminous. The order is Titan, Rhea, Iapetus, Dione, Tethys, Enceladus. An IP changed it from sixth to fith (sic). If its an error lets fix it quick.

Reedman72 (talk) 22:14, 6 April 2014 (UTC)

Heat source

I spent most of 12 hours reading papers on the likely heat sources. Measurements and interpretations varied with time and techniques, which caused confusion not just in this article, but in the planetary science circles. Basically, tidal heating could not produce more than 1.1 gigawatts power, but the observed infrared signals are much greater than that. One estimate went as high as 15.9 GW, and the latest (2013) brought it down to 4.7 GW. Scientists are still not able to justify the "excess" heat observed emanating from the south pole (tiger stripes). I may have done mistakes in the review, but the punchline is that the heat source must be actually combination of sources; tidal heating is one, but the rest remain a mystery. CHeers, BatteryIncluded (talk) 05:05, 7 April 2014 (UTC)

Does the maximum figure of 1.1 GW include the effect of excitation by the other Saturnian moons? --JorisvS (talk) 09:30, 8 April 2014 (UTC)

It should. The model seems well accepted, so it should include all nearby planetary bodies capable of contributing to the tidal heat. BatteryIncluded (talk) 12:17, 8 April 2014 (UTC)

All right. What about a local decrease of thermal insulation? --JorisvS (talk) 13:12, 8 April 2014 (UTC)

It seems the hot spots in the south pole are not because a thinner crust or decreased insulation, but because of the fissures (tiger stripes). BatteryIncluded (talk) 13:28, 8 April 2014 (UTC)

Well, if there is warm material flowing out of the fissures, that would effectively decrease the thermal insulation in those areas. --JorisvS (talk) 14:28, 8 April 2014 (UTC)

The image for the cryovolcanism shows the surface ice temperature as "-77K". It is probably 77K and someone just tossed in the negative sign. I dont know the real temp so i figured i would just mention it and leave it to someone who knows to fix it. — Preceding unsigned comment added by 50.79.188.77 (talk) 14:42, 9 April 2014 (UTC)

Good question. Actually, the image displays not -77K but a tilde, squiggly line (~) which means "approximately" 77K. Thank you. BatteryIncluded (talk) 18:01, 15 April 2014 (UTC)

Ice

It may be obvious but it needs to be made clearer that Enceladus is an icy moon. It isn't mentioned in the intro and it isn't mentioned in the surface features section. Ice and water are a fairly important part of its identity. Serendi^podous 08:51, 28 April 2014 (UTC)

Reliability of source

Does anyone have a view on why this webpage prepared by someone called Alexander Clarke should be considered a reliable source? (currently used in footnote 45). hamiltonstone (talk) 02:12, 30 April 2014 (UTC)

The cleanup is a work in progress. Thank you. --BatteryIncluded (talk) 07:34, 30 April 2014 (UTC)

Flattening of Enceladus's rotation axis...

Regarding:

... have led to a flattening of Enceladus's rotation axis ...

How can a rotation axis be flattened? Isn't it the moon itself that is being flattened? --Mortense (talk) 21:18, 8 June 2014 (UTC)

Yes it sounds weird. I'll read the references and context. --BatteryIncluded (talk) 01:57, 9 June 2014 (UTC)

The source (Porco et alii) actually says "more oblate" and "less oblate". I've restored the sentence and fixed the wording. Tbayboy (talk) 03:32, 9 June 2014 (UTC)

Stop it!

People, quit moving this page back and forth without getting a consensus. Double sharp: saying "we should discuss this" in an edit summary while moving a page over a move over a move... what gives?? hamiltonstone (talk) 03:14, 20 June 2014 (UTC)

I've moved it back for the discussion. (I still think that it looks odd if it's the only moon not needing dismabiguation, and that some other moons in the Solar System may well also be way more well known than their mythological counterparts. (I also note that we have situations Chaldene redirecting to Chaldene (moon), with no article on the mythological character: granted that's not exactly a major moon, but shouldn't we also have the article without disambiguation?) Double sharp (talk) 03:28, 20 June 2014 (UTC)

Similar arguments have been brought up elsewhere on Wikipedia, for example here and here. Consistency is important, but as those discussions show, consistently following WP:PRECISE outweighs consistency with using the same parenthetical disambiguations, especially when those parenthetical disambiguations are unnecessary. Precision shouldn't be ignored just because other articles are at their appropriate levels of precision. If other articles have unnecessary parenthetical disambiguations, the solution would be to fix those articles and bring them in line with Wikipedia guidelines rather than to add unnecessary parenthetical disambiguations to article titles just to have them "match". (Also, thank you for moving it back and discussing it) - Aoidh (talk) 03:40, 20 June 2014 (UTC)

OK, I see. I think I'll go through some of the other moons and remove the disambiguation where it's not necessary. I'm sorry about the repeated moves. Double sharp (talk) 10:03, 20 June 2014 (UTC)

Question about intro paragraph

The third paragraph of the intro reads, in part:

...Enceladus is geologically active today. Moons in the extensive satellite systems of gas giants often become trapped in orbital resonances that lead to forced libration or orbital eccentricity. Enceladus is in such a resonance with Saturn's fourth largest moon, Dione. Enceladus's proximity to Saturn leads to tidal heating of its interior, offering a possible explanation for the activity.

I'm wondering whether there is any logical relation between sentences 2&3 and sentence 4. Geological activity comes from tidal heating which comes from proximity, but does proximity have anything to do with Dione resonance? Thanks, AxelBoldt (talk) 17:18, 15 March 2015 (UTC)

Tidal forces lead to dissipation of heat, but at some point an equilibrium state is reached. Perturbations from other satellites bring it out of this equilibrium, and those of satellites with which it is in resonance tend to be the strongest (which is the "that lead to forced libration or orbital eccentricity" part). The order of the sentences is not ideal and how they say it is not something a layman would understand. Especially the last sentence is off. I have taken a shot at improving it. --JorisvS (talk) 20:53, 15 March 2015 (UTC)

@JorisvS: Thanks a lot; being a layman, I can confirm that it makes a lot more sense now. I think the sentence about the ocean fits better in the second paragraph though; I'll give it a shot. AxelBoldt (talk) 15:31, 16 March 2015 (UTC)

That's good! And I think your move makes sense, too. --JorisvS (talk) 18:25, 16 March 2015 (UTC)

Saturn Moon's Ocean May Harbor Hydrothermal Activity

I just got this in the Mensa Weekly Brainwave:

11 Mar 2015 (Source: NASA Jet Propulsion Laboratory)

Things to know:

• Cassini finds first evidence of active hot-water chemistry beyond planet Earth
• Findings in two separate papers support the notion
• The results have important implications for the habitability of icy worlds

NASA's Cassini spacecraft has provided scientists the first clear evidence that Saturn's moon Enceladus exhibits signs of present-day hydrothermal activity which may resemble that seen in the deep oceans on Earth. The implications of such activity on a world other than our planet open up unprecedented scientific possibilities.

"These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "The locations in our solar system where extreme environments occur in which life might exist may bring us closer to answering the question: are we alone in the universe."

Hydrothermal activity occurs when seawater infiltrates and reacts with a rocky crust and emerges as a heated, mineral-laden solution, a natural occurrence in Earth's oceans. According to two science papers, the results are the first clear indications an icy moon may have similar ongoing active processes.

The first paper, published this week in the journal Nature, relates to microscopic grains of rock detected by Cassini in the Saturn system. An extensive, four-year analysis of data from the spacecraft, computer simulations and laboratory experiments led researchers to the conclusion the tiny grains most likely form when hot water containing dissolved minerals from the moon's rocky interior travels upward, coming into contact with cooler water. Temperatures required for the interactions that produce the tiny rock grains would be at least 194 degrees Fahrenheit (90 degrees Celsius).

"It's very exciting that we can use these tiny grains of rock, spewed into space by geysers, to tell us about conditions on -- and beneath -- the ocean floor of an icy moon," said the paper's lead author Sean Hsu, a postdoctoral researcher at the University of Colorado at Boulder.

Cassini's cosmic dust analyzer (CDA) instrument repeatedly detected miniscule rock particles rich in silicon, even before Cassini entered Saturn's orbit in 2004. By process of elimination, the CDA team concluded these particles must be grains of silica, which is found in sand and the mineral quartz on Earth. The consistent size of the grains observed by Cassini, the largest of which were 6 to 9 nanometers, was the clue that told the researchers a specific process likely was responsible.

On Earth, the most common way to form silica grains of this size is hydrothermal activity under a specific range of conditions; namely, when slightly alkaline and salty water that is super-saturated with silica undergoes a big drop in temperature.

"We methodically searched for alternate explanations for the nanosilica grains, but every new result pointed to a single, most likely origin," said co-author Frank Postberg, a Cassini CDA team scientist at Heidelberg University in Germany.

Hsu and Postberg worked closely with colleagues at the University of Tokyo who performed the detailed laboratory experiments that validated the hydrothermal activity hypothesis. The Japanese team, led by Yasuhito Sekine, verified the conditions under which silica grains form at the same size Cassini detected. The researchers think these conditions may exist on the seafloor of Enceladus, where hot water from the interior meets the relatively cold water at the ocean bottom.

The extremely small size of the silica particles also suggests they travel upward relatively quickly from their hydrothermal origin to the near-surface sources of the moon's geysers. From seafloor to outer space, a distance of about 30 miles (50 kilometers), the grains spend a few months to a few years in transit, otherwise they would grow much larger.

The authors point out that Cassini's gravity measurements suggest Enceladus' rocky core is quite porous, which would allow water from the ocean to percolate into the interior. This would provide a huge surface area where rock and water could interact.

The second paper, recently published in Geophysical Research Letters, suggests hydrothermal activity as one of two likely sources of methane in the plume of gas and ice particles that erupts from the south polar region of Enceladus. The finding is the result of extensive modeling by French and American scientists to address why methane, as previously sampled by Cassini, is curiously abundant in the plume.

The team found that, at the high pressures expected in the moon's ocean, icy materials called clathrates could form that imprison methane molecules within a crystal structure of water ice. Their models indicate that this process is so efficient at depleting the ocean of methane that the researchers still needed an explanation for its abundance in the plume.

In one scenario, hydrothermal processes super-saturate the ocean with methane. This could occur if methane is produced faster than it is converted into clathrates. A second possibility is that methane clathrates from the ocean are dragged along into the erupting plumes and release their methane as they rise, like bubbles forming in a popped bottle of champagne.

The authors agree both scenarios are likely occurring to some degree, but they note that the presence of nanosilica grains, as documented by the other paper, favors the hydrothermal scenario.

"We didn't expect that our study of clathrates in the Enceladus ocean would lead us to the idea that methane is actively being produced by hydrothermal processes," said lead author Alexis Bouquet, a graduate student at the University of Texas at San Antonio. Bouquet worked with co-author Hunter Waite, who leads the Cassini Ion and Neutral Mass Spectrometer (INMS) team at Southwest Research Institute in San Antonio.

Cassini first revealed active geological processes on Enceladus in 2005 with evidence of an icy spray issuing from the moon's south polar region and higher-than-expected temperatures in the icy surface there. With its powerful suite of complementary science instruments, the mission soon revealed a towering plume of water ice and vapor, salts and organic materials that issues from relatively warm fractures on the wrinkled surface. Gravity science results published in 2014 strongly suggested the presence of a 6-mile- (10-kilometer-) deep ocean beneath an ice shell about 19 to 25 miles (30 to 40 kilometers) thick.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. The Cassini CDA instrument was provided by the German Aerospace Center. The instrument team, led by Ralf Srama, is based at the University of Stuttgart in Germany. JPL is a division of the California Institute of Technology in Pasadena.

More information about Cassini, visit:

http://www.nasa.gov/cassini

and

http://saturn.jpl.nasa.gov

Preston Dyches Jet Propulsion Laboratory, Pasadena, Calif. 818-354-7013 preston.dyches@jpl.nasa.gov

Dwayne Brown NASA Headquarters, Washington 202-358-1726 dwayne.c.brown@nasa.gov

Source web site, gorgeously illustrated with uncopyrighted drawings:

http://solarsystem.nasa.gov/news/display.cfm?News_ID=48922

☺ Dick Kimball (talk) 16:36, 17 March 2015 (UTC)

MansourJE (talk) 11:06, 7 May 2015 (UTC)

Curtain Erruptions

New research and photos from Cassini satellite shows diffusing volcanic activities rather than discrete jets. Read more on the following like: http://phys.org/news/2015-05-saturn-moon-curtain-eruptions.html MansourJE (talk) 15:40 7 May 2015 (UTC)

FWIW - the following image => File:PIA19061-SaturnMoonEnceladus-CurtainNotDiscrete-Eruptions-20150506.jpg - seems related - and has been added to the main Enceladus article - also available => more images & video animation - iac - Enjoy! :) Drbogdan (talk) 11:41, 7 May 2015 (UTC)

Although Hubble and Cassini have seen the plumes, it may be useful to note that some scientists think it may be a very rare phenomenon to exploit or rely on.[1] -Cheers, BatteryIncluded (talk) 17:15, 7 May 2015 (UTC)

That's only about Europa, not Enceladus. --JorisvS (talk) 17:55, 7 May 2015 (UTC)

Sorry! BatteryIncluded (talk) 17:56, 7 May 2015 (UTC)

Merge discussion at Talk:Life on Enceladus

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

Global ocean

I fail to see why evidence for a global ocean is not worthy of the lede but a previous line about evidence for a localised South-polar sea is? Can someone enlighten me? ChiZeroOne (talk) 23:54, 15 September 2015 (UTC)

That not really either, just a general sentence about the existence of a subsurface ocean. The details can be given in the section about it. That's one of the things that have to be cleaned up. People tend to put new findings in the lead, even though often they don't belong there. More often than not that stuff stays there. --JorisvS (talk) 00:07, 16 September 2015 (UTC)

Global ocean and disequilibrium

Is it possible to have a global ocean with a crust on top that does not have the shape corresponding to hydrostatic equilibrium? If it does, how could it support the disequilibrium? --JorisvS (talk) 23:49, 3 October 2015 (UTC)

Why is this article so good?

I mean, Enceladus is just a small moon, sixth largest Saturnian moon, it doesn't have a huge potential for life, etc. Congratulations to those who brought it to featured article status. Huritisho 05:16, 6 October 2015 (UTC)

Yes, a global subsurface water ocean with energy sources is over-rated. BatteryIncluded (talk) 06:47, 6 October 2015 (UTC)

NASA-TV/ustream (10/26/2015@2:00pm/et/usa) - "Enceladus FlyBy" Teleconference.

NASA-TV/ustream and/or NASA-Audio (Monday, October 26, 2015@2:00pm/et/usa) - NASA will detail an "Historic FlyBy" through a "plume of icy spray" of Enceladus on 11:22 am/et/usa Wednesday, October 28, 2015 - Enjoy! :) Drbogdan (talk) 02:10, 23 October 2015 (UTC)

BRIEF Followup - REPLAY LINK (Audio; 43:41) => http://www.ustream.tv/recorded/76308203 - Enjoy! :) Drbogdan (talk) 19:37, 28 October 2015 (UTC)

References

WP:BOLD removal of Atmosphere section

I have removed the atmosphere section of this article after concluding that scientific discussion of Enceladus's atmosphere to date has focused almost exclusively on the south polar plumes, which are adequately covered by the Cryovolcanism section. More explanation of this below. Feel free to revert and discuss here if you disagree with my rationale.

Reviewing all four references for the Atmosphere section, two were press articles from March 2005, when NASA apparently announced the discovery of an atmosphere on Enceladus. The other two ([2] [3]) were from scientific papers published together a year later in March 2006. Tellingly, in their abstracts, neither paper discusses an atmosphere, but both discuss plumes from Enceladus's south polar region (one paper uses the term "atmospheric plume"). With information from the Cryovolcanism section (referenced to one of the same papers from the Atmosphere section), I pieced together the story behind this: in January and February 2005, Cassini unexpectedly detected water over Enceladus, which NASA reported to the press as the discovery of an atmosphere (hence the March 2005 articles). Further observations in mid and late 2005 "determined that gases in Enceladus's atmosphere are concentrated over the south polar region, with atmospheric density away from the pole being much lower", i.e. the "atmosphere" initially detected turned out to be plumes from the south polar region. This explains why the scientific papers from March 2006 discuss plumes rather than atmosphere. A cursory search for other scientific papers on Enceladus's atmosphere revealed that almost all of them discuss the south polar plumes exclusively. While Enceladus has a very thin global atmosphere (probably from the plumes), I don't think that the scientific literature to date allows us to write a section on it that is meaningfully different from the Cryovolcanism section. A2soup (talk) 12:28, 12 January 2016 (UTC)

A more likely reason for the Enceladus paradox

We need to understand that there is a gravitationally induced temperature gradient that forms at the molecular level and is based on the quotient of the acceleration due to gravity and the weighted mean specific heat of the solids, liquids or gases involved. We see this in all planets and satellite moons. We can indeed explain the small temperature increase of about 30 degrees between the surface and core in Mimas using the specific heat of ice. But Enceladus (diameter 500Km) has just over twice the volume of Mimas (diameter 390Km) and greater density due to the rock. This means that the force of gravity may well be three or four times as great. Also, because of the lower specific heat of most rocks, that also makes the temperature gradient steeper. It is not out of the question that the temperature of the core might get above 273K (not the estimated 180K to 200K) because of these factors and the fact that there is a greater distance between surface and core, thus not even requiring the supposed heating by tidal forces.