Talk:Titan (moon)

Sub-Saturnian point

I'm not happy with this sentence:

Because of this, there is a sub-Saturnian point on its surface, from which the planet would always appear to hang directly overhead.

Yes, I realise the point it is trying to make but it is doing do in an over-strong and clumsy manner: Titan has measured eccentricity and thus its sub-Saturnian point moves over the course of an orbit within a well-defined region of the surface, as for the more familiar example of lunar libration. Indeed, the reference for the sentence following regarding longitude specifically refers to the average sub-Saturnian point. Even if we had no measured eccentricity the conclusion would not flow automatically from the simple fact of a synchronous orbit (as implied by the overly-assertive "Because of this") simply because of the mere possibility of there being eccentricity to throw into the mix.

I'm not sure the best way to rectify this - my initial impression is that if it is toned down and clarified to something correct it gets diluted to a point not worth making and therefore better snipped entirely. Thoughts, anyone? 3142 (talk) 18:01, 25 March 2017 (UTC)

The article also notes that the sub-Saturnian point is also the Greenwich of Titan, so if it moves, then the 0 longitude must be some average. Serendi^podous 19:46, 25 March 2017 (UTC)

"The only [...]": really?

The article states: "Titan is the largest moon of Saturn. It is the only moon known to have a dense atmosphere, and the only object in space other than Earth where clear evidence of stable bodies of surface liquid has been found."

Is s it set in stone that no other moons exist on any other planet in the solar system? Or at the very least, is it highly likely that no other moons exist orbiting any other planet?

Finally, of all registered moons, have all of them been as thoroughly observed as Titan was?

Failing a definitive answer to the questions above, I'd precede the quotation with "Currently": "Currently, it is the only moon known to have [etc etc]"

There are certainly a lot of other moons that we have not seen, but they must all be very small rubble piles, and certainly much too small to hold on to any atmosphere. Double sharp (talk) 10:52, 18 September 2017 (UTC)

First, the complaint is un-necessary because the word "known" is already included. Titan is described as the "only moon known" to have a dense atmosphere. The word "known" indicates the current state of human knowledge. Furthermore, unless there are moons found orbiting planets as yet undiscovered at great distance far beyond Neptune, there is zero chance that there are "currently" unknown moons with dense atmospheres. This is simply a statement of scientific fact: Titan is the only moon with a dense atmosphere in the Solar System (to the orbit of Neptune and far beyond). — Preceding unsigned comment added by 2600:1000:B12F:37AD:4496:BD1:B881:BA32 (talk) 17:43, 18 January 2018 (UTC)

Yes, "known" being included is the kicker. MaximusEditor (talk) 20:45, 16 September 2020 (UTC)

Sixth "ellipsoidal moon"

The article begins (third sentence) by saying that "Titan is the sixth ellipsoidal moon from Saturn". Linking to a mathematics article on ellipsoidal is worthless. No one uses this language to describe Titan EXCEPT Wikipedia. The concept of an "ellipsoidal moon" is presumably fallout from Plutonian irredentism. — Preceding unsigned comment added by 2600:1000:B12F:37AD:4496:BD1:B881:BA32 (talk) 17:37, 18 January 2018 (UTC)

I removed the sentence. Again, this was not a "normal" or "common" description of Titan. It was a Wikipedia-ism without support.2600:1000:B120:B65:44C8:F791:F62A:B550 (talk) 19:08, 19 January 2018 (UTC)

The difference between the "roundish" moons (which have room for actual geology, being more than rubble piles: Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Iapetus) and the others is certainly well-established in the literature. It was probably more often referred to as these moons being in hydrostatic equilibrium than being ellipsoidal, but this presents difficulty as data from Cassini has shown that among these, only Rhea and Titan are currently in HE. I will note that "ellipsoidal" also poses problems, because of Methone. So this distinction is certainly not a "Wikipedia-ism without support", and it is also not Plutonian irredentism to note that there is some difference between gravitationally rounded objects and the others. What poses a difficulty is the language we need to use to describe this with. Double sharp (talk) 07:12, 20 January 2018 (UTC)

You agree that referring to these potentially geologically-active moons as ellipsoidal is not as useful categorization. You also are aware that hydrostatic equilibium is not a well-defined categorization for the moons of Saturn. That's fine then. Referring to Titan as the "sixth ellipsoidal moon" is not effective --even outside Wikipedia. You also mentioned that that the difficulty is the language used to separate the major moons from the minor moons (beyond those vague words "major" and "minor"). That's true, too. There is no well-established language that separates the moons of Saturn into categories like this unambiguously. The bigger problem is that this language difficulty you describe is not Wikipedia's problem. A Wikipedian editor should not make up expressions and categorizations, like "ellipsoidal moon", that are not found in the scientific literature. That's basic and fundamental to Wikipedia. When a Wikipedian editor invents his or her own terminology or categories, then that's what I call a Wikipedia-ism.174.199.32.8 (talk) 20:31, 20 January 2018 (UTC)

I do not agree that "ellipsoidal moon" is a Wikipedia-ism. It is simply an adjective "ellipsoidal" applied to a noun "moon", and reliable sources can be found for each claim (that it is ellipsoidal, and that it is a moon). Similarly, referring to iodine as a "volatile nonmetal" would not be a Wikipedia-ism, since it is volatile and it is a nonmetal. And, in fact, there is a quite adequate adjective we can use: "gravitationally rounded", as in List of gravitationally rounded objects of the Solar System. I will edit the article to use that, since it is accurate. Double sharp (talk) 02:48, 21 January 2018 (UTC)

Surface: what's it made of?

I've been looking for clear descriptions of what the surface is made of. For instance, the intro details how the atmosphere is mostly nitrogen, there's dunes, rivers, lakes of methane & ethane, cryovolcanos - but not clear what the solid part of the surface is made of. The cutout diagram shows a green layer of 'normal ice' just under the yellow surface skin - but what's that skin like? The section on 'Surface Features' doesn't help much. Little hints like "There is also evidence that Titan's ice shell may be substantially rigid, ...", ice shell could be any layer. Finally in the Impact craters section we get this confession: "Pre-Cassini models of impact trajectories and angles suggest that where the impactor strikes the water ice crust, a small amount of ejecta remains as liquid water within the crater."

From these clues, I've figured out that the non-lake surface is made of water ice. That should be stated in the intro, clearly. And I know it's not pure water ice. If I was walking around in my space suit, and picked up a "rock", it wouldn't look like a clean ice cube, it would look dirty or at least opaque. Just like granite doesn't look like clear glass. Somebody must know some details about this.

PS: I use the term "water ice" because, when you're talking about the outer planets, lots of things are frozen solid. As in the term "ice giant". OsamaBinLogin (talk) 19:04, 11 August 2019 (UTC)

The short answer is that scientists don't know, but have a good idea. The dense atmosphere complicates the use of orbiting spectrometers. The Huygens probe was not a "lander" but an atmospheric probe that happened to make it all the way to the ground, so we have more info on the atmospheric composition than info on the surface. It did, however, collect images and info on the physical properties of the surface, but not its chemical composition (no soil samples analyzed). You are correct in that there is a strong suspicion on the existence of a mix of ices on the surface (cryovolcanoes were imaged, I think), but these surface ices are also mixed with wild and complex kinds of organics collectively called tholins, so there is not one kind of surface "composition" one could quote at this time. Fortunatelly, Dragonfly (spacecraft) was selected for launch, and your questions will begin to be answered soon after landing in 2034. Cheers, Rowan Forest (talk)

There is some surface composition data from Huygens and Cassini. One of the Huygens instrument suites was "Surface Science Package", although it would have worked better if the probe had landed in a lake or sea, and it got material not chemical properties of the surface. The Gas Chromatograph and Mass Spectrometer made a sort-of chemical composition measurement. The inlet was heated and close to (or against) the surface, and they got a measure of whatever surface materials were evaporated by heat from the inlet. And, despite the atmosphere, the Cassini VIMS instrument did get plenty of surface spectra. Unfortunately, they are actually of the surface and the atmosphere, and require lots of modeling to get the surface contribution. So there is data, it just has lots of "ifs" and "assumings." It's basically a mix of hydrocarbons, nitriles and cyanogens, but the details are uncertain. That wasn't a big surprise. Haze particles which grow big enough settle to the surface. There's probably a few places with bare rocks, and the depth and exact composition of the gunk varies spatially. Now, is any of that worth adding the article, and if so, how much of it? — Preceding unsigned comment added by Fcrary (talk • contribs) 22:11, 27 September 2019 (UTC)

Titan as the 6th of 7 gravitationally rounded moons.

This is a continuation of the comments I made for my January 17th Edit: I have read this paper (Thomas P.C. (2010)) and while the author does note that Iapetus does not have a rotation period consistent with being in equilibrium on page 397, he also notes the moon as being an “oblate spheroid” which is consistent with gravitational rounding. It should also be noted that on page 399 in the list of “irregularly-shaped satellites” Iapetus is not included. Therefore I argue that while Iapetus may not be technically in hydrostatic equilibrium it is obviously highly gravitationally rounded, which is consistent with other Wikipedia articles. Therefore, Titan is the 6th of 7 gravitationally rounded moons of Saturn.Violettsureme (talk) 23:41, 17 January 2021 (UTC)

I don't have the reference handy, but there is a paper (I think Matson et al.) on the subject. It argues that Iapetus was in hydrostatic equilibrium at some time in the past. At that time, it solidified enough that its shape no longer changed. Since then, tidal evolution has moved it farther from Saturn and slowed its rotation rate, but the shape of Iapetus did not change with its rotation rate. But going into that in an article about Titan isn't necessary. I think it's safe to say Iapetus is "gravitationally rounded" and that Titan is therefor one of seven moons of Saturn which are. Fcrary (talk) 01:30, 18 January 2021 (UTC)

Correction. The paper I was thinking of is Castillo-Rogez et al., Icarus 190 (2007) 179–202. Matson was the second author. Iapetus would be in hydrostatic equilibrium if it had a 16 hour rotational period, and presumably solidified sufficiently to fix its shape at a time when it's rotation period was 16 hours. Fcrary (talk) 01:41, 18 January 2021 (UTC)

Atmospheric pressure

The article says that Titan's atmosphere is twice as thick as Earth's. But that source is years old. I updated the info from an article just some months old, from NASA's own pages. Straight from the horse's mouth in other words. This update was inexplicably reverted shortly after. By someone who doesn't seem to have checked the source. The same person did the following reversions in the same time span (on average 20 seconds between each reverting):
08:52, 25 February 2021 diff hist −1‎ Green Revolution ‎ Undid revision 1008821763 by 74.139.166.18
08:51, 25 February 2021 diff hist −185‎ Titan (moon) ‎ Undid revision 1008822694 by 46.212.126.226
08:51, 25 February 2021 diff hist +5‎ Bonsai Kitten ‎ Undid revision 1008825300 by 2600:8801:D200:2DF0:38A7:986C:E9B6:6387
08:51, 25 February 2021 diff hist 0‎ Mikheil Gelovani ‎ Undid revision 1008825931 by 2401:4900:51F6:96D4:A36C:13BB:6AE3:EB82
08:50, 25 February 2021 diff hist +6‎ Carl Jung ‎ Undid revision 1008834131 by 207.161.86.162
At least take the time to read the links before succumbing to a reverting frenzy.
Wikipedia:IPs are human too 46.212.126.226 (talk) 06:34, 3 March 2021 (UTC)

It is true that the atmosphere is about four times denser than that of Earth (near surface). Ruslik_Zero 14:36, 3 March 2021 (UTC)

I think the problem is that the article says "thick". Some people may read that as pressure, some as density and some as column density. Column density is probably the most technically correct way to read it. But the relation between the three depends on temperature and gravity. Maybe we should decide on which one we mean and say so in the text. Fcrary (talk) 19:26, 3 March 2021 (UTC)

Yes, it would probably improve the article for Titan (and Mars and Venus) if one could be specific about pressure and density (and column density). But so far I haven't read any articles that goes into detail regarding all these facts. If anyone knows about one, the info could be added to the article. 46.212.126.226 (talk) 00:53, 5 March 2021 (UTC)

Error - inverted sentence

"From Titan's surface, Saturn subtends an arc of 5.09 degrees and, were it visible through the moon's thick atmosphere, would appear 11.4 times larger in the sky than the Moon from Earth." it doesnt feel sensible to compare "plant (S) viewed from moon (T)" with "moon viewed from planet (E)" - a more logical yet relatable example/comparison seems to be with "sun (large) viewed from earth (small)" . the con for that would be the huge difference in scale of distances in between though. any views/thoughts/clarifications?? 3rd thought, what is relevance/significance of this fact point?? like is it used somewhere etc? Yashpalgoyal1304 (talk) 16:19, 4 August 2021 (UTC)

Please clarify the meaning of "the con for that". In modern English, a "con" means an attempt to commit fraud, as in a "con job". That doesn't seem to be what you're trying to say, so a clarification would be useful. Fcrary (talk) 03:48, 5 August 2021 (UTC)

i meant the negative side of the proposed change. took from the use in "pros vs cons of a product". Yashpalgoyal1304 (talk) 07:37, 5 August 2021 (UTC)

" body in space"

is ambiguous. Do we mean space the dimension? Interplanetary space? Intergalactic space? I know it seems grandiose, but it is nonetheless true, and more precise, to say that Titan and Earth are the only known places in the universe on which surface liquids have been found. That is a fact. Serendi^podous 13:01, 13 August 2021 (UTC)

What about just saying that the Earth and Titan are the only "planets or moons" known to have surface liquids? Fcrary (talk) 18:10, 13 August 2021 (UTC)

That works. Serendi^podous 18:15, 13 August 2021 (UTC)

speculation and theory needs to be delineated from actual fact.

regarding whether titan has 'oceans" of "water" is a theory that is being investigated. People are getting confused by sourcing "rivers" and "oceans" and "ice" which are actually referencing hydrocarbon oceans and rivers, etc. water is not an hydrocarbon. Here (below) is a good article to include, but i suck at editing. note this article talks about the hydrologic cycle, but it is referencing it in terms of hydrocarbon dynamics, not water. any assertion that there are oceans of water under the surface are speculative and hypothesis, particularly given the topological data that there are lakes of hydrocarbons on the surface.

https://earthsky.org/space/scientists-find-new-surprises-about-titans-lakes/

I think you are confusing two things. The seas and lakes on the surface of Titan are hydrocarbons. The subsurface ocean has been identified by two or three independent measurements, and almost certainly has to be water. There is no evidence that the surface hydrocarbon bodies of water are connected to the much deeper subsurface ocean. But if the article is unclear about that, I guess we need to make some changes and clarify the matter. Fcrary (talk) 03:45, 14 September 2021 (UTC)

New study show that Titan's subsurface ocean is not habitable for life.

There is a new paper just now: Titan is ruled out (for now) as a candidate abode for extraterrestrial life.

https://astrobiology.com/2024/02/titan-is-most-likely-not-habitable.html IapetusCallistus (talk) 17:44, 15 February 2024 (UTC)