Talk:Enceladus (moon)

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Contents

[edit] Translation

This article has been partly translated from the article fr:Encelade (lune) under GFDL license. Please have a look at the history to know the list of authors.

English pronunciation [en-SELL-uh-dus].

[edit] Atmosphere

An atmosphere exists around every larger body of the solar system. The substantial information which is missing here is the pressure / density of the atmosphere. 193.171.121.30 18:52, 18 Mar 2005 (UTC)

The press release announcing the discovery gave no information on the atmospheric properties, only that it is "substantial", whatever that means. --Jyril 20:13, Mar 18, 2005 (UTC)

Although the planetary society article[1] says "a million million times less" which means a factor of 1012, it's actually a factor of 1011 if the number of 200 to 300 million atoms/molecules per cm3 stated in the same article is correct. I think one order of magnitude does matter. 194.166.218.217 01:55, 23 September 2005 (UTC)

[edit] False color image

I definitely prefer the old picture over the new false color image. I will revert, if nobody objects! Awolf002 13:15, 27 Apr 2005 (UTC)

Done. Awolf002 13:55, 28 Apr 2005 (UTC)

Yes, on Titan (moon) the concensus was that the main image of a body should look as realistic as possible. Specifically, false-colour images were considered inferior. In fact, apparently you were the one who reverted that one.  :-) --P3d0 17:52, Apr 28, 2005 (UTC)
I'm not at all sure that the current image has true colors whatever that means. Enceladus, with its extremely high albedo, is actually bright white or gray, not brown like in this image which looks like a colorized one. But I've to admit that the current image looks much better.--Jyril 19:45, Apr 28, 2005 (UTC)

Yes, there should be a better picture, since this is an old Voyager image, I believe. I will take a look at the JPL/Cassini image archive. Awolf002 19:58, 28 Apr 2005 (UTC)

I can only find raw images, close-up images of the surface, or false color images that are better than the Voyager image. All other visible light images from the whole moon have less resolution. However, those pictures show a white surface! Should we replace? Awolf002 20:14, 28 Apr 2005 (UTC)

Personally I would include both on the page. Most of the images I have added following my revisions earlier this month are high resolution images that don't show the whole disk and perhaps one of the full disk images from Cassini could be added to highlight the blue cliffs of Enceladus (to go along with the high resolution image I have for that purpose. Volcanopele 17:37, Jun 20, 2005 (UTC)

Would this image be more appropriate: [2]? It's a toned-down stretched color view so it should be reasonably close to natural color. The tiger stripes are really too subtly bluish to be noticeable in a natural color view. Ugo 11:53, 17 October 2006 (UTC)
I think so; The present infobox image suggests that Enceladus is brown, which is way off. Deuar 19:45, 17 October 2006 (UTC)
I like this image, however I have a few of suggestions before we switch the title image. First, the Cassini image should be rotated 30 Degrees CCW so that North is up. The image should also be trimmed to remove the excess black space. The current title image, from Voyager 2, should be retained in the article, though perhaps only as a greyscale image so that people aren't confused about Enceladus' "real" color. --Volcanopele 22:46, 17 October 2006 (UTC)
OK, I've uploaded a new version, rotated so north is up and clipped excess blackness around it. If anyone wants to use it, it's here: [3]

[edit] Mass and Density Figures

I have updated the mass and density numbers for Enceladus based on a presentation given by Zibi Turtle last month (not my only source of that information, but it is the only public mention of the change that I am aware of). The density figure is now 1.6 g/cm3, compared to the previous value of 1.3. This update is based on the Cassini NAV team's assessment of the reconstructed trajectory of Cassini following two recent flybys. This makes Enceladus denser than the other Saturnian mid-sized icy satellites, suggesting that it is composed of more iron and silicates that those other moons. I'm planning on making a mention of this in the article itself. Volcanopele 22:06, 01 Jun 2005 (UTC)

There have been a few updates to the mass numbers lately by other members, mostly because I forgot to change the source on some more recent figures. I have once again put in the more recent numbers (1.08x10^20 kg; 1.61 g/cm^3) based on the GM numbers in the Cassini pck SPICE kernels. I have now linked to the source of those numbers, but the calculations are my own. If others want to check my work, go ahead, just make sure to read the documentation in the source document on the units used for GM (gravitational constant times the mass), so you do the right conversions. I also used a different radius for density, escape velocity, and surface gravitational acceleration from the March 9 flyby. Volcanopele July 6, 2005 19:54 (UTC)

[edit] Major changes coming

I am working on some major edits to the Enceladus article after having spending the last week working on Enceladus images. The edits will be confined to the "Physical Characteristics" section, plus a new section on the history of Enceladus exploration. The Physical Characteristics section will have the following outline:

  • Interior
  • Surface
    • General Geology
      • Voyager 2 results
      • New Insights from Cassini
    • Impact Craters
    • Tectonics
    • "Planitia"
    • Cryovolanism?
  • Atmosphere

This would generally follow an inside out approach to discussing this satellite. The atmosphere section will largely remain intact as it is now, though I may de-emphasize the "current events" nature of the section.

Just wanted to give a heads up to the changes I am working on.

- Volcanopele 19:29, Jun 3, 2005 (UTC)

I have updated this article again, to attempt to fold in some of the results from the July encounter and from the plume images from November. As such, I have removed the atmosphere section. It is now becoming increasingly clear that the Magnetometer, UVIS, and INMS instruments didn't see an atmosphere, per se, but a plume emanating from the south pole, made of water vapor and dust. So, I have folded the information in the atmosphere section into the cryovolcanism section, where I feel it belongs. Volcanopele 23:23, 2 December 2005 (UTC)
I am very pleased with the changes you've implemented. Thank you for your contribution. --vex5 00:38, 10 March 2006 (UTC)

[edit] Temperature

What is Enceladus' surface temperature? Googling seems to mostly repeat the tidbit mentioned here, that is to say 70 K. But that's way too hot for the albedo of 0.99! 70 K implies an albedo of 0.67-0.68; an albedo of 0.99 implies 29 K (but that value is very sensitive to the actual albedo at that point). Anyone have an actual measurement they can quote?

Urhixidur 2005 July 5 03:43 (UTC)

This says it was measured in February. What was the result?

Urhixidur 2005 July 5 03:45 (UTC)

I recently read a source with temperatures derived from Voyager IRIS data. I'll need to find it again and post the information here. In terms of Cassini results, I don't think the Cassini CIRS results from the flyby have been posted, and certainly not temperature data, AFAIK.
Also, don't forget that other factors contribute to surface temperature, including surface roughness, as well as albedo.
Volcanopele July 6, 2005 19:44 (UTC)
Okay, found it, from Cruikshank et al. (2005):
"The High albedo of Enceladus results in a colder surface than most of the other satellites, with a calculated subsolar temperature of 75 +/- 3 K, and an average temperature of ~51 K. Volcanopele July 6, 2005 23:07 (UTC)
I have found that the original source of the 75 +/- 3 K value comes from a paper by R. Hanel et al. (1982)., using infrared data from the IRIS instrument. This temperature results in a bolometric bond albedo of 0.89±0.02 and a phase integral of 0.89±0.09 (as opposed to the geometric albedo of 0.99). Volcanopele July 7, 2005 20:53 (UTC)
I've updated the page with the temperatures from the refererence above. I'll look into the albedo issue some more, particularly how that temperature was estimated, and see if I can find a better estimate, but that is the only mention of surface temperature I have found thus far in the literature. Volcanopele July 7, 2005 20:35 (UTC)
Using an emissivity of 0.9, a geometric albedo of 0.91 gives a mean T of 51 K; if we stick to a geometric albedo of 0.99, then the emissivity has to go down to about 0.1 to reconcile the temperature. Not altogether impossible, just unlikely (the calculation is, understandably, very sensitive to the geometric albedo value as it nears 1).
Urhixidur 2005 July 8 00:24 (UTC)
That calculation isn't supported by the geometric albedo observed by both ground-based and spacecraft observations which consistently show an albedo of 0.99±0.01 (Franz and Millis 1975, Cruikshank 1979, Smith et al. 1982, Buratti and Veverka 1984, Buratti 1988). For temperature measurements, it is the bond albedo that is important here, not the geometric albedo. Bond albedo is also known as the spherical albedo, and is the fraction of the total incident solar radiation—the radiation at all wavelengths—that is reflected or scattered by an object in all directions. As I said above, this value is 0.89±0.02, which is consistent with the value you came up with. Volcanopele July 8, 2005 19:01 (UTC)
Found an even better reference, Verbiscer and Veverka 1994, which reported that the single-scattering albedo (another way of saying geometric albedo), is 0.997±0.001 for disk-resolved images (value an average of all terrains). Volcanopele July 8, 2005 19:37 (UTC)
Another problem has occured to me regarding the temperatures reported here. What exactly constitutes a max, mean or min temperature. Is the max the average sub-solar temperature, the min the average midnight temperature, and the mean the average between the two? Is the max the maximum surface temperature (as a result of differences in thermal inertia/volcanism), the mean the average sub-solar temperature, the min the average nighttime temperature? What is the convention at wikipedia, if there is any? Volcanopele 17:30, July 20, 2005 (UTC)

[edit] Energy source for cryovulcanism partially molten core?

The energy budget for Enceladus's cryovulcanism, and suggested energy source are discussed briefly in a Science news article at [4]. I'll let someone else write it up; it's past my beddy-bye time. kwami 12:00, 8 January 2006 (UTC)

Never mind, I got it. Also covers a possible subsurface ocean, which is what that life comment may have been about. kwami

[edit] "Debunking evolution"

The fact that Enceladus is geologically active has been used by Creationists to supposedly debunk evolution, since they say that Enceladus has not cooled yet and therefore must be young and recently-created. See [5]. - Brian Kendig 14:47, 16 February 2006 (UTC)

Yuck. Those people are really desperate. I'm sorry for the people who actually listen to them.--Jyril 15:43, 16 February 2006 (UTC)
totally offtopic, but yeah, I agree. I think scientists should start referring to Evolution as "the laws of evolution" as opposed to "the theory of evolution". Just like nobody says 'theory of gravity' anymore. --Philo 11:15, 13 March 2006 (UTC)
People do talk about the theory of gravity. No one doubts that gravity exists, but the theory of gravity attempts to explain the fact of gravity, just like the theory of evolution attempts to explain the fact of evolution.--RLent 19:06, 17 March 2006 (UTC)
Well, thank you all for being so kind as to actually respond to their good point (rolls eyes). This is just another example of insulting people when you have no good answers. I predict that if any of you come back, you will insult me for saying this, but I don't care since I do not live for the glory of man. --Twipie 13:49, 13 March 2006 (UTC)
Since you asked . . . . . The fact that Enceladus hasn't frozen solid proves nothing, since its internal heat is being generated anew all the time. The gravitational pulls of Saturn and its other moons cause Enceladus to stretch and contract in various directions. This process generates heat. There may also be radioactive material decaying in the moon's core, but the gravitational effect alone is more than ample explanation. If Enceladus were somehow stuck with only the amount of heat it contained a billion years ago it probably would have solidified by now, but that's a really big "if". In fact, it's so big it's nonsensical.
The earth also has not frozen solid, but that fact doesn't contradict evolution either. I don't understand why creationists think a molten interior in another body proves something that Earth's molten interior doesn't.
Um, there is nothing kind in substituting beliefs as science. For a scientist it is an insult. Creationism is not science, it doesn't rely on the scientific method. If one claims otherwise, he either doesn't know the basic principles of science or he has some ulterior motives and is therefore no less than lying. Wikipedia must stay NPOV, that is obvious, but adding pseudosciences into scientific articles is disastrous for Wikipedia's reliability. I don't mind introducing pseudoscience/alternative ideas, but keep them in their own articles and describe them as such.--Jyril 07:00, 16 March 2006 (UTC)

Obviously this nonsense from 'creation science' is easy to debunk, and everyone should be ready to enter into open-minded scientific debate with those prepared to participate in good faith. However those who masquerade as scientists in order to confuse public opinion and undermine the integrity of the discipline should not be entertained. This only lends credibility both to the con-men and to the false notion that there is a real scientific debate about creationism. Intellectual dishonesty should not be dignified with a response. 213.202.153.201 04:21, 16 March 2006 (UTC)

please, no one put any creationism stuff in here. it is totally irrelevant. and enceladus is most likely kept active by tidal forces as with jupiter's io. and anyway creationists, how come active moons are so rare? what about tethys, dione, rhes, hyperion, iapetus, mimas - saturns dead moons? Ezkerraldean

Also, people may have noticed that evolution explains the origin and diversification of life, nothing to do with the solar system. Perhaps the argument was young earth theory vs. old earth theory

[edit] Surface water

It looks like NASA is going to report at 2pm EST (about one hour from now) that there's liquid water near the surface of Enceladus. [6] -- Plutor 17:51, 9 March 2006 (UTC)

Does the water that is released escape from the planet, or does it eventually settle back down? I didn't see at what velocity is is released. Also, if there is life in that water, I woner if it might be possible to send a probe to sample the water that is released to see if there are any microorganisms.--RLent 20:09, 9 March 2006 (UTC)

Is there anything in the article about this yet?I think it should have it's own section this a very importent secientific discovery.--Scott3 01:39, 11 March 2006 (UTC)

I agree with you Scott3. the info about water is just basically scattered around the article. I think it should warrant a section, like "Discovery of Water" or something --Philo 11:21, 13 March 2006 (UTC)

I agree and I think some of it is contradictory as well. Rmhermen 23:51, 13 March 2006 (UTC)
I'm not sure this is such a big news to be inserted in a dedicated section. Two competing hypothesis (already present in this article) have been proposed for a long time, one magmatic-like with a huge layer of ammonia/water slurry, and one geyser-like with pressurized chambers of nearly pure water. The news here is that, in this month Science magazine issue, scientists seem to declare themselves much more confident with the second one. On reading this papers, it don't seems to me that there is any proof of this, but only clues. So I think the article should be rewritten to reflect this state of the competing hypothesis, without a dedicated section, and maybe rename the "Cryovolcanism" section to reflect the new state of mind. (I'm not a native english speaker, and I know that my english is not very good, so if you don't understand what I'm trying to say, well, never mind, excuse me and forget it :) Stanlekub 08:38, 14 March 2006 (UTC)

[edit] Image

Is this image copyright?

http://solarsystem.nasa.gov/multimedia/gallery/Enceladus_PIA06254_full.jpg

its picture of Enceladus with a very good resolution showing high details of it

would be nice to put this picture on the article

201.19.148.85 21:27, 9 March 2006 (UTC)

No. This image is in the public domain because it was created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". --vex5 00:29, 10 March 2006 (UTC)
After 2 months of forgetting, image added to article.--Volcanopele 01:59, 31 May 2006 (UTC)

[edit] Geologically Active

Is it too much of a stretch to include Venus alongside Enceladus, Triton, Io and the Earth? It does present some kind of vulcanism. PHF 21:42, 9 March 2006 (UTC)

Yes, it is, because active volcanisim, although widely suspected, has not been confirmed on Venus. bob rulz 21:56, 9 March 2006 (UTC)

[edit] Pronunciation

Why specify pronunciation when it's incorrect? Enceladus is a Greek word, and would be pronounced eh-nke-lah-dos. In Latin it is eh-ncheh-lah-doos. If Anglo-Saxons want to continue to badly pronounce words (another blatant case is that of scientific names of animals and plant)... but please don't confound other language people reading the English WikipediaAttilio.

For one thing, Wikipedia should not be prescriptive, but descriptive. We have no business telling people what is correct and incorrect. For another, ενκέλαδος is a Greek word but enceladus is definitely an English word, and is pronounced [ɛnˈsɛlədəs] according to the rules of English orthography. —Keenan Pepper 22:22, 9 March 2006 (UTC)
Now, the question is whether many English speakers actually pronounce it [ɛnˈkɛlədəs]. If so, then it should be given as one of two alternate pronunciations. Personally I've never heard that pronunciation. Anybody? —Keenan Pepper 22:26, 9 March 2006 (UTC)
Some people use the Latin pronunciation rather than the English, which is why the original is included. Since there are multiple opinions as to how the Latin or Greek should be pronounced, it's best just to use the original orthography and not make a prescriptive attempt with the IPA.
Actually, the word "ενκέλαδος" does not exist in Greek. The n "ν" is replaced with a gamma "γ" when followed by k. The word is pronounced en-geh-lah-thos, the ng part as you would pronounce "anger." And delta is pronounced as th in "the", "then" etc. Not as d. -djak
I was just about to say that! You beat me to it. —Keenan Pepper 23:51, 9 March 2006 (UTC)
Good catch. As for the pronunciation, that depends on which form of Greek you're attempting to capture: since Classical Greek distinguished γγ from γκ, it's a good bet that they were pronounced differently, presumably [ŋg] and [ŋk]. And of course [d] for δ. kwami 00:06, 10 March 2006 (UTC)

I've tried to restore things back to how they were status quo ante (except for the well-noted correction of the Greek to gamma-kappa). We already had a standard for all the satellite pages with listing both an English phonetic transcription, using only schwa as a special character, followed by the IPA /transcription/, then the Greek spelling. Arguments about how it is pronounced in MODERN Greek are out of place in this article. Sorry, but English pronunciation of Classical Greek and Roman names date back to Shakespearean times. To suggest it must be pronounced today as /eng-KEHL-ah-dhohss/ is hypercorrection gone ad absurdum. A reminder that this satellite of Saturn is NOT the actual mythological Titan, but named after it. We astronomers would just as gladly call it 'Saturn II' again. ;) I am concerned though about the actual Greek spelling a bit as I think about it though. Could nu-kappa be correct if it is etymologically an affix en put in front of celados? --Sturmde 01:11, 10 March 2006 (UTC)

As far as I know, Greek orthography does not allow nu before the velars gamma, kappa, chi, or ksi. There are no words starting with eng or enk in the concise Liddell & Scott, and in most of the words starting egg and egk, the eg- is a prefix. kwami 01:59, 10 March 2006 (UTC)
After the Pioneer 11 or Voyager 1 encounter with Saturn, National Geographic noted that scientists couldn't agree on the pronunciations. Some pronounced it en-say-LAD-us, making it sound like a Mexican dish. Mimas was the same: My-mas or Mee-mas. I agree, though, that as words have entered English, we have applied English pronunciation rules to part or all of the words, and the reverse is true as English words were added to other languages: television being "tay-lay-vee-zyon" in French. For us, when a C is followed by an E, I or Y, we make it a soft C.


New question: what do you folks think the adjective form would be? "Enceladian?" How about "Enceladine?"

I've seen Enceladean used. But to be honest, I haven't seen the adjective form used in print very often. --Volcanopele 19:05, 19 September 2006 (UTC)

[edit] Picture

What has an owl got to do with this?

  • Some stupid vandalism. Fixed now, Guinnog 03:59, 11 March 2006 (UTC)
Someone put a picture of an owl on the article? Kamope | userpage | talk | contributions 23:27, 11 January 2007 (UTC)

[edit] visual geometric albedo = 1.41???

How can v.g.e. of Enceladus bee 1.41 (>1) ??? --Ante Perkovic 06:03, 11 April 2006 (UTC)

Good question. I've cited the source for that information, which comes from data taken from Hubble Space Telescope and Hapke modeling of the Enceladus photometric function. Using observations taken near several oppositions, Verbiscer et al. was able to model the brightness of Enceladus at phase angle = zero, the visual geometric albedo. This result has been cited by a number of authors, including those of the recent ISS article on Enceladus.
I'll try to track down an answer to how it can be greater than 1. --Volcanopele 18:00, 11 April 2006 (UTC)
I've reinserted the 0.99 Albedo and clarified that 1.41 is the geometric albedo, a different measure that can be greater than 1 due to the backscattering from the opposition effect. However I could not determine what kind of albedo the 0.99 refers to - bolometric (heat) or visual? More clarification is at [7], but I also await a better answer. -213.219.186.138 22:01, 15 April 2006 (UTC)
Then what number is used for albedo in planetary articles?? I've always assumed that the standard number to use for albedo is the visual geometric albedo, which in Enceladus' case is 1.41, NOT 0.99. Are we supposed to use some other number? Single-scattering albedo (0.998 for Enceladus)? Bolometric albedo (0.85 for Enceladus, I think)? I don't really care which number we use but we should at least be consistent from article to article, not just change it to some other standard just because we are uncomfortable with the result. If all the articles are supposed to use visual geometric albedo, than the figure is 1.41. --Volcanopele 18:02, 17 April 2006 (UTC)
Volcanopele, thank you for the link to leading the author’s (Anne Verbiscer) explanation. I’m afraid countless popular sources, and many considered more that e.g. wolfram, define albedo in a way that bounds the upper limit to 1. This is for example the case of the papers on TNOs, implicit in our article on absolute magnitude, a handy H to D calculator, and quick look-up Minor Planet Center. Introducing (only for the icy moons?) and without a proper warning a value based on a very technical definition causes IMHO unnecessary confusion. Eurocommuter 16:48, 2 May 2006 (UTC)
I understand, but I still don't like the idea of pulling a number out of a hat and calling that "albedo", just because the number used is not liked for the reasons you cited. I'm happy to accept another convention (there are all many different types of albedo). But if we use an albedo, whether it be single-scattering albedo, bond albedo, or whatever, it should be consistent across all articles, not just visual geometric albedo (as is used on all other articles as far as I knew) for most articles except for when it is above 1, then its something else. If the albedo numbers for the other articles came from some website, that just said "albedo", where did they get that number.
I apologize for sounding a bit forceful, but I would like to see us remain consistent between articles.Volcanopele 18:00, 28 May 2006 (UTC)
Well, the albedo issue is now rearing its ugly head. A new paper by Verbiscer et al. in tomorrow's issue of Science, provides updated values for the albedo's of many of Saturn's satellites, based on HST observations taken in January 2005. The article states that these new values, while many are above 1, update the values appearing in other Wikipedia articles. For example, for Dione, it lists 0.55 (the value currently in the Dione article) as the "old" value from Burns et al. (1986), and 0.998 as the new value. For the sake of consistency and accuracy, the articles this paper affects should be updated with these new values, regardless of whether other sources explain geometric albedo correctly (perhaps the articles in wikipedia can updated to explain this). --Volcanopele 22:12, 8 February 2007 (UTC)
Oh no, don't tell me that the dreaded unspecified albedo is striking again! Or worse, perhaps, it's been around all along but I've been blissfully hiding my head in the sand on the issue for a while. Seriously, though, the straightforward way to remain accurate is to explicitly state what kind of albedo is being given (somehow, it's almost never obvious, unfortunately). Then it will also become much clearer whether all the values given for different bodies are consistent or not. Deuar 13:09, 9 February 2007 (UTC)

[edit] Eccentricity

The data box gives the eccentricity of Enceladus's orbit as 0.0045 but elsewhere in the article it's given as 0.0047. The article should be consistent. Does anyone know which figure is the correct one? Reyk YO! 21:36, 20 May 2006 (UTC)

Refs gives 0.0045 so I changed the other to remain consistent. -- Grafikm (AutoGRAF) 20:00, 27 May 2006 (UTC)
Okay then. Thanks. Reyk YO! 02:52, 28 May 2006 (UTC)
0.0047 comes from the more recent Porco et al. 2006. Changed both eccentricity mentions and added reference. --Volcanopele 01:15, 9 June 2006 (UTC)

[edit] Expanding the article

I started to gradually expand the article, getting missing info from the French version of the article. However, my copyediting skills are quite low and therefore, your help is welcome there... :)) -- Grafikm (AutoGRAF) 19:51, 27 May 2006 (UTC)

I've expanded the lead section. Still only two paragraphs, so maybe someone can expand it further.
Since I am the cause of some of the text being a bit too technical, I'll see what I can do about toning down the language a bit, but I would want to do that without losing the info contained within, particularly in the south polar and cryovolcanism sections.Volcanopele 18:03, 28 May 2006 (UTC)
I've gone ahead and cleaned up some of the technical language in the article as well as trimmed off some that can be stated in another way.--Volcanopele 20:34, 30 May 2006 (UTC)

[edit] Images

The cutting down in size of this article, and the continual addition of pictures over time, has caused this article to become far too flooded with pictures. Shall I propose removing some of them? I love them all...but we just can't have that many. The article looks cluttered (becuase, well, it is). bob rulz 01:07, 31 May 2006 (UTC)

  • I agree. We can probably do without figures 7, 8 and 11. I'm not convinced 15 is necessary either, but because it is near the end of the article and relatively distant from other pictures it's probably OK. Reyk YO! 01:23, 31 May 2006 (UTC)
Hmmm...yeah, that sounds about right. bob rulz 01:37, 31 May 2006 (UTC)
Many of the images help to show geologic aspects explained in the text (that's why all the images are numbered, for quick reference from the text. Figure 15 could go, but I am unconvinced that we can get rid of the other three without damaging the connections made between the text and the figures. That being said, I could see removing Figure 13 (since Figure 7 basically covers the same area at better resolution). Plus, the section it is in doesn't really match the image.--Volcanopele 01:53, 31 May 2006 (UTC)
My concern is that figures 6,7 and 8 are too close together. That's where the cluttering is most obvious. And it's not entirely clear to me what surface features Fig 7 shows that aren't on Fig 6. Reyk YO! 03:46, 31 May 2006 (UTC)
What do you know, a figure to replace Figure 13 has been released ;) what a coincidence...--Volcanopele 18:33, 31 May 2006 (UTC)

Personally, I'm not a fan of false/enhanced color views as the main image; couldn't we have a true color image from Cassini instead of that pinkish Voyager image? Even a grayscale image would be more accurate than this one for all practical purposes. EDIT: Nevermind, I see that discussion was already ongoing in another section.Ugo 11:08, 17 October 2006 (UTC)

[edit] Featured article

Well, with the recent overhaul made to this article, I believe it's closer to featured status than the previous version. Some minor cleanup, removal of some pictures, and perhaps more varied language, is all that's really needed to make this into a featured article now. However, I can't quite remember how long you have to wait before you re-submit it. Who remembers how long it is, or is there any time limit? In fact, isn't the featured article candidacy still going? Who even agrees with me? bob rulz 02:55, 2 June 2006 (UTC)

It's still a canadate, who knows, it's close enough where it might even still pass. I don't think there's a set rule, but I'd wait a few weeks at least if it doesn't pass. Tuvas 07:31, 2 June 2006 (UTC)

:Well, bob rulz, you could strikethrough your original "oppose" already to make it a FA :))))) --Grafikm (AutoGRAF) 09:06, 2 June 2006 (UTC)

It is featured! Woohoo! :) -- Grafikm (AutoGRAF) 15:44, 2 June 2006 (UTC)
Alright, now for the other moons. :) --Planetary 10:10, 15 July 2006 (UTC)
    • really beautiful article :) Strange to see a very good article as an FA. FA's are usually not so good articles. congratulations. --Pedro 17:14, 19 July 2006 (UTC)

[edit] Featured Article of the Day

Enceladus (moon) will be the featured article of the day tomorrow, July 20, 2006. Such exposure usually brings a flood of edits, both constructive and vandalism. A quick look at the edit histories of recent TFA's suggests that upwards of 100 edits can be expected tomorrow. By policy, Featured Articles of the Day are not semi-protected to guard against vandalism, so it would be helpful if people who watch this page keep an eye out starting at midnight UTC for problems. Hopefully, after tomorrow, thousands of people will become better acquainted with Enceladus and this article can be made better thanks to its increased exposure. Thanks to everyone who helped get this article to this point. --Volcanopele 20:55, 19 July 2006 (UTC)

I'll be watching and, no doubt, reverting! Looking forward to seeing this article on the main page. Worldtraveller 21:11, 19 July 2006 (UTC)
I've noticed that User:Raul654 removed the Special Characters note. Is this template falling out of favor? I put it up there because of issues I've noticed with my work computer regarding the characters used in the IPA pronounciations in the lead paragraph. This issue forces me to use a different computer if I need to edit the lead paragraph or the info box (elsewhere I can just edit by section on my nominal computer). I'll certainly understand if that template has fallen into disfavor, but it seems appropriate for this article. --Volcanopele 06:16, 20 July 2006 (UTC)

[edit] Awesome article!

I think the sections on tectonics may be a teensy bit too detailed, but overall a tremendous job. I really enjoyed reading it.--Anchoress 00:53, 20 July 2006 (UTC)

Yeah...can you guess what I do research on ;-) Anyways, regarding your edit of the Spahn et al. 2006 reference in the Cryovolcanism section, earlier in the day, I tried to fix that reference but forgot to remove the now extra citation. The Spahn et al. paper is referenced twice in the article, first in the "Interactions with the E-ring" section then in the cryovolcanism section. The "E-ring" section had been below the cryovolcanism part, and when the ering section was moved the full citation was not shifted, causing the Spahn et al. 2006 citation in "Notes and References" to appear blank. I fixed that earlier without removing the now duplicated info in the cryovolcanism. I've fixed this now. --Volcanopele 01:02, 20 July 2006 (UTC)
NP. I totally don't know how refs work, like I really don't know, so I was just shooting in the dark removing the / to see if it would fix it. I didn't know to check if there were previous refs to that ref, but I was worried that you might have thought my edit added all the ref junk, the URLs etc. When I removed the / and it worked (I didn't think to preview lol), I was like, 'Woo Hoo! Go ME!' But your way was better. :-) --Anchoress 01:12, 20 July 2006 (UTC) EDITED TO ADD: Re; the article, I particularly like the pics. IMO some of the best pics (most useful and relevant, as well as high-quality) in any article I've seen.--Anchoress 01:16, 20 July 2006 (UTC)
  • To all that worked on this article: absolutely fantastic work. The NASA pics are especially lovely. Space stuff? Always cool... :) Wickethewok 05:43, 20 July 2006 (UTC)

[edit] I liked Enceladus before it was cool to like Encaladus.

I read about it in a book when I was 12 and I liked the name and a few other things, so I decided it was my favorite of Saturns moons, but then all this water stuff happened and now everyone likes it. I'll bet people think I'm a copycat for liking it now. >:| Nick Warren 11:24, 20 July 2006 (UTC)

  • My favorite is... I can't decide. Hyperion definently up there, with it's spongy looks (Most sci-fi looking thing ever to exist), and so is Titan, obviously. Iapetus is odd too, with the "seam", the two-faced complexion, and of course we can't forget Mimas, which looks like some gigantic eyeball, just staring.--Planetary 08:22, 22 July 2006 (UTC)
  • Actually Mimas is my favorite since it resembles the Death Star, and interestingly enough was discovered 3 years after Star Wars was released. -- Riffsyphon1024 14:15, 24 July 2006 (UTC)
    • As far as being twelve and fascinated by the cosmos, it's the Voyager 2 pictures of Neptune I remember best (not the most unique choice of body, sorry). They are still some of the most beautiful and haunting images I have ever seen. Marskell 15:15, 24 July 2006 (UTC)
Those were some of my favorites, too. Neptune has always been my favorite planet (besides Earth, of course). And I've been suspecting these discoveries at Enceladus ever since the discoveries at Europa...bob rulz 17:27, 24 July 2006 (UTC)
the best space pic i've ever seen, although "fake". Ok, these are just balls, but remember these are also worlds on their own.
the best space pic i've ever seen, although "fake". Ok, these are just balls, but remember these are also worlds on their own.

.

  • I think Titan, Europa, Triton, Io, and obviously Mars are more fantastic than Enceladus. For me Titan and Mars had always been my favourites planets, plz don't say Titan isn't a planet. Pluto seems great as it is maybe similar to Triton, but we know nothing about it, maybe in a few years from now. I dont like gaseous "planets", but those planets have cool moons. --Pedro 17:52, 24 July 2006 (UTC)
    • Titan would be a planet if it orbited the sun by itself, not around Saturn. No one says the Moon is a planet, and Titan isn't either. It's certainly planet-like, and larger then Pluto and Mercury, but it's not a planet anymore then I am. :) --Planetary 21:52, 24 July 2006 (UTC)
    • Let's not debate those issues here. That's more complicated than you think. For me, it's a planet or if you want a more scientific approach it is a "secondary planet". In my and some other people's perspective a planet is a physical identity like a star. A human is still a human, even if he changes his home from the UK to the USA. --Pedro 22:13, 24 July 2006 (UTC)
      • Good point Pedro.--Planetary 04:58, 25 July 2006 (UTC)
  • No, you're all wrong. Gas giants are way cooler than terrestrial planets. All the lightning and storms and heat and pressure just can't be beat. I once had a dream I was piloting some fancy space plane through the cloudtops of Jupiter. I'd like to do that someday. I wonder if the sky there is green like in my dream. Also, a body becomes a Moon once it enters orbit around a planet. It doesn't matter how big it is. If Earth orbited Saturn (which would be pretty cool, if it weren't for the radiation and all the tidal flexing) Earth would be a Moon too. Nick Warren 21:25, 5 August 2006 (UTC)

[edit] The formation

this mite b a very supid question but because of the size of Enceladus, and the fact that the ring its located in is so disipated compared to the other rings of saturn, is it that Enceladus was formed from the particles in the ring it is orbiting in. and therefore could all of saturns rings end up becoming moons?

No question is stupid, I reckon. It turns out to be the other way around - Enceladus is actually the source of the E ring, and is actually losing particles to it. The ring is caused by outgassing from Enceladus. As for the other rings, I believe they get more energy from perturbations by all the Saturnian moons than they stand to lose from agglomerating into larger clumps. The end result is that the ring particles are actually getting more anfd more pulverised with time. Deuar 20:39, 3 April 2007 (UTC)


so if the moon as actually feeding the E-ring, then when the moon (moons) disseperates completly into the ring (rings) then will they gravitate back into moons - by which the whole process starts again. if this is the case, then why isnt our solar system much like this? the plantes wer indeed formed by rocks and dust/ice particles gravitating into each other, why did they not just break apart? and feed astroid belts?--Infinitive definition 13:01, 4 April 2007 (UTC)

Sorry, I don't follow — why would it gravitate back to moons? In any case, the time for Enceladus to lose an appreciable portion of its mass to the ring is likely longer than the remaining lifetime of the solar system. Deuar 15:18, 4 April 2007 (UTC)

[edit] The mass is wrong

The infobox says: "Mass: 1.08022 ± 0.00101×1021 kg [5] (1.8×10-5 Earths)". I don't live near an academic library to check the source, but everything else says the mass of Enceladus is about 1020 kg, not 1021. Most likely the 21 is a typo that should be simply changed to 20. Other sources:
1. Earth says the Earth is 5.9736x1024 kg, so 1.8x10-5 Earths is 1.075x1020 kg.
2. #Mass and Density Figures says "1.08x10^20 kg".
3. Your first external link [8] says 8.40 e+19 kg.
4. Your second external link [9] says 7.30e19 kg.
5. Your fifth external link [10] says 1.2x1020 kg. Art LaPella 01:26, 27 April 2007 (UTC)

You're correct, the 1021 is a typo, that should instead be 1020. I have corrected this in the article. BTW, the sources in 3 and 4 are using pre-Cassini mass values. --Volcanopele 01:31, 27 April 2007 (UTC)

[edit] New Papers from Cassini data

There are a couple of statements on the page that could use some refreshes based on new papers published May 2007. They can be found through [11] and [12], with a partial summary and discussion available from Ars Technica.

One particular point of note is the hypothesis and supporting theoretical analysis that the source of the geyser material is not an internal reservoir, but ice-melt heated along fault lines. This now-contradicted point is mentioned in the article's third paragraph of the introduction.

Under "Interaction with the E Ring", the text reads "This hypothesis was proven by Cassini's flyby." Hypotheses in general are supported and confirmed, but proof is a poor choice of words. 134.173.58.19 03:29, 17 May 2007 (UTC)

[edit] Sky from Enceladus references

The section "Sky from Enceladus" has a note saying that it is missing references. The section has no information that can't be calculated directly from the information in the articles on Enceladus and on Saturn, but I will put in a reference saying so. Geoffrey.landis 14:26, 5 October 2007 (UTC)'.

[edit] I will merge it

I created Atmospher of Enceladus I will merge it with Enceladus (moon) --Krishan1020 13:07, 12 October 2007 (UTC)

The information covered in The Atmosphere section you keep adding is already covered in the Cryovolcanism section of this article, where it properly belongs. Enceladus does not have an atmosphere, like the Earth, Mars, or Io have atmospheres. What was thought for a brief time to be an atmosphere is instead a plume centered over the south polar region of Enceladus. I know you are trying to be helpful, but this article is already long as it is and adding a section that contains redundant information does not help matters. --Volcanopele 22:08, 25 October 2007 (UTC)

[edit] Axial tilt

The infobox says "Axial tilt zero". No axial tilt can be zero (a superbeing would have to keep the axis aimed in exactly the right direction.) Does it mean "Axial tilt small" or "unknown"? Art LaPella 03:46, 6 November 2007 (UTC)

Enceladus being tidally locked and its rotation being synchronous, it means precisely that the tilt is zero. No superbeings involved, only tidal forces at work. The moon most likely librates a bit in its orbit due to a finite eccentricity, but the back-n-forth libration is also directed along the rotation axis.--Ugo 12:20, 6 November 2007 (UTC)
Resolved. Art LaPella 02:20, 7 November 2007 (UTC)

[edit] Recent research re: Enceladus and Ring A

Saturn's Giant Sponge (NASA, 02.05.08) the paper is Farrell et al. Mass unloading along the inner edge of the Enceladus plasma torus, doi:10.1029/2007GL032306. Circeus (talk) 21:27, 7 February 2008 (UTC)

[edit] Cassini Flythrough of the South Pole Water Plume

Editor - Per the mission website: "This is the third and final targeted flyby of Enceladus in the prime mission. It is an inclined flyby with a closest approach distance near the equator of about 50 kilometers, enabling the first good views of the northern hemisphere. The trajectory will take Cassini through the plume at a grazing angle (deeper into the plume than during the July 2005 flyby), allowing for fields-and-particles measurements within the plume. Enceladus will enter eclipse (Saturn's shadow) shortly after closest approach, allowing for thermal measurements of the south pole at high resolution." - JPL Cassini Science Team (http://saturn.jpl.nasa.gov/operations/index.cfm)

This flyby is already mentioned a couple of times in the article. If we add a new section for every new flyby, this article would get ridiculously long considering that this is the 4th of 10 planned. If the results from the flyby requires a change to some of the text in the Cryovolcanism section, a change should be made then. The only change I can see needing to be made (and I did just make) is that the article refers to 3 close flybys having been preformed by Cassini. Close approach for today's encounter has occurred so the number has been incremented up one. --Volcanopele (talk) 21:36, 12 March 2008 (UTC)

Vol - Thanks for reply. Very quick! From my scan of the article - "The discoveries Cassini has made at Enceladus has prompted several studies into follow-up missions. In 2007, NASA performed a concept study for a mission that would orbit Enceladus and would perform a detailed examination of the south polar plumes.[26] The concept was not selected for further study.[27] The European Space Agency is also exploring plans to send a probe to Enceladus in a mission to be combined with studies of Titan.[28]"

I also read on further for mention of today's (2008 Mar 18) flythrough in a context other than planned. I did not find any. Maybe I read through too quick?

The context of this one is interesting. First one for Casini (or any other craft I can think of) to dive into a water plume off-world.

Thanks for upping the counter.

More info here (http://blogs.nasa.gov/cm/blog/Enceladus%20Flyby) —Preceding unsigned comment added by Damian792 (talk • contribs) 22:12, 12 March 2008 (UTC)

Here - "These discoveries have prompted the adjustment of Cassini's flight plan to allow closer flybys of Enceladus, including an encounter in March 2008 which will take the probe to within 50 km of the moon's surface." Adjusted that to make it past-tense. --Volcanopele (talk) 06:23, 13 March 2008 (UTC)

[edit] Astrobiology section

Given Enceladus' composition which includes liquid water, I think there should be an astrobiology section in this article. Anyone know of any literature on the topic? I'll see if I can find anything. Jackkoho (talk) 19:31, 17 March 2008 (UTC)

Found this paper from 2006 - Parkinson, Liang, Hartman, Hansen, Tinetti, Meadows, Kirschvink, Yung - "Enceladus: Cassini observations and implications for the search of life" - Astronomy and Astrophysics, 463, 353–357 (2007)

Perhaps an astronomer or astrobiologist could give this article a read and add a paragraph on Enceladus and astrobiology. Jackkoho (talk) 19:39, 17 March 2008 (UTC)

Why? Has life been found on Enceladus? Organic material? sure. Water ice and vapor? Sure. But no life as far as I am aware. I don't see why an astrobiology section should be added if there is no evidence for it. What is known and theorized regarding the south polar region and its plume is in the article. Any info that would be in an astrobiology section (unless we want to go the route of the Europa article and add things that have nothing to do with Enceladus) is there in the Cryovolcanism section. --Volcanopele (talk) 20:29, 17 March 2008 (UTC)
It seems you are against talking about astrobiology at all, anywhere. I think some things similar to the Europa article would be great. If we can't talk about astrobiology in places where it might be suspect, then we are simply limited to the article Astrobiology. Jackkoho (talk) 16:58, 18 March 2008 (UTC)
But what would an astrobiology section add that isn't in the cryovolcanism or south polar region sections (or could be added to those sections)? The only thing you could add is speculation or science that isn't related to Enceladus (which is a BIG problem with the one in the Europa article, which talks about life at Earth's mid-ocean ridges. It is one thing to mention that Enceladus might be a potential habitat for life due the presence of liquid water (possibly), hydrocarbons, and an energy source, but I don't believe we can go beyond based on the published sources available now. --Volcanopele (talk) 17:18, 18 March 2008 (UTC)