Talk:Titan (moon)/Archive 1

False-colour image
(Doradus) Does it make sense to have a false-colour image as the image for this article?


 * IMO, the "primary" image for a planet or moon should be as close to true-colour as possible. I recall there was a similar discussion over the image for Venus (planet) a while back, and while the current primary image isn't true-colour (it's in the ultraviolet, a true-colour image of Venus is pretty much featureless) it's still closer than the Magellan radar map that was there for a little while. Bryan 02:20, 28 Oct 2004 (UTC)


 * I think the old image should be put back and the new false colour image should replace the older, low-quality one at the bottom which has now been superseded. I'd do it myself but I've got to go to work!! The Singing Badger 12:19, 28 Oct 2004 (UTC)

Done. Awolf002 14:26, 28 Oct 2004 (UTC)

"Significant atmosphere"
[no user login] - article refers to Titan as only N2 rich atmosphere. Believe Triton's atmosphere is almost pure N2


 * It is a question of reification  (¿when is a thing a thing?).   Some gas is around Triton.  ¿Is sufficiently thick to me an atmosphere?  ¿Is our moon airless or does it have an extremely thin atmosphere of sodium-vapor?  ¿Is Io airless or does it have an atmosphere of sulfur-vapor?  ¿Is Europa airless or does it have a thin atmosphere of oxygen?  ¿Is Mercury airless or does it have an atmosphere of helium?  ¿Is intergalactic space airless or does it have an Hydrogen/Helium-atmosphere with a density of one atom per cubic centimeter?  Most planetologists ask themselves, "¿Whether the world has weather?"  Triton is a bordercase:

If the Nitrogen of Triton would just lie around, it would make support clouds. Triton has geysers. The nitrogen significantly slows the fall of particles from the geysers. One could argue it either way. Personally, I would say that Triton has an insignificant atmosphere. Titan, on the other hand has a very significant atmosphere '' (both in mass and density, the atmosphere of Titan is greater than that of Earth). ''

--

&#364;alabio 02:10, 2005 Jan 15 (UTC)

I know this might seem a silly question, but would Titan's whole atmosphere burst into flames if someone lit it with a match? Impaciente 19:31, 21 September 2005 (UTC)


 * Not a silly question, but easy to answer. First of all, unstable situations like you're imagining don't stick around for millions of years. If a spark could set off Titan's atmosphere, it would have happened long ago. Or, more likely, an atmosphere of methane never would have been stable enough to form in the first place. The fact that it could develop shows it's stable.


 * As for why it's stable, methane (like anything else) needs a reactive combining fluid in order to burn. On Earth that fluid is oxygen gas. I suppose it could also be chlorine or fluorine gas. But none of these exist on Titan, at least not in sufficient quantities for things to burn. Also, even if there were oxygen, Titan's atmosphere might be too cold to support combustion, like trying to ignite cold wet wood on Earth. kwami 21:57, 21 September 2005 (UTC)


 * Thank you. That was a very enlightening answer. Impaciente 07:08, 22 September 2005 (UTC)


 * Yes, that was a good answer. One thing though: Temperature may not be such an issue after all. I work at a science museum and while playing with some liquid nitrogen, I got curious. I lit a sparkler and tossed it in the flask. To my astonishment, the sparkler kept burning. This is negative 320 degrees Farenheit! So, maybe you could actually get a fire going on Titan--if you could find the right reactants. Aelffin 10:40, 16 August 2006 (UTC)

Would it not be pertinent to include discussion to explain how Titan at only 40% of the earth's diameter can have an atmosphere ten times the density as the earth's atmosphere?


 * The atmosphere is only about 4 times times as dense (1½ times the pressure at (⅓ the temperature). It is 15 times more massive.  The reason a body with such a low escapevelocity can hold a significant atmosphere is its low temperature.

—

— Ŭalabio‽ 03:47, 30 October 2005 (UTC)

Interior
I couldn't find anything in the article about the interior of Titan- did I miss it, or have we missed it out? This BBC report suggests that the interior is a rather exciting place: ''"However, models of Titan's interior show there should be an ocean about 100km deep at around 300km below the surface." If the models are correct, this ocean would be composed mostly of liquid water with about 15% ammonia at a temperature of about -80C''. Mark1 06:16, 26 Jan 2005 (UTC)


 * I don't think ESA and NASA has information about Titan's interior...yet.--puk 01:08, 21 January 2006 (UTC)

Methane Oceans
There have been headlines in the science press about the discovery of methane lakes at both of Titan's poles, thus we should have a major revision here.

I know ESA talks a lot about methane oceans and lakes, but the fact is methane partial pressure in titan is insufficient for condensation, so methane is only stable as a gas and as a solid.

Ethane lakes can exist, and there is a lot of ethane around. Ethane can dissolve methane, so those lakes can be a mix of ethane+methane.

So, should this be mentioned in the article?

--Rnbc 18:52, 2005 Jan 28 (UTC)


 * If those are true facts (not saying they aren't just that I don't personally know whether they are) then by all means they should be in the article. This is exactly the sort of information encyclopedia articles are for. :) Bryan 00:44, 29 Jan 2005 (UTC)


 * Ideally, you'd also give a citation for your information. --Doradus 04:10, Jan 29, 2005 (UTC)


 * Well, you can just grab your calculator and do some math yourself :-) Methane triple point pressure (taken from wikipedia) is 11700 Pa, so that's the absolute bare minimum partial pressure for condensation. Titan's average temperature seems just above methane's triple point (-182C), at -180C, so we are ok from a temperature POV. Now the problems start: The atmosphere has only 6% methane and the pressure at the surface is about 160000 Pa, witch means methane partial pressure is only ~9600 Pa, below the bare minimum 11700Pa required for condensation. On Earth the atmospheric water content is much below 6%, but the triple point condensation pressure is only 611 Pa, so this is not a problem. For water condensation to occur on Earth only 0.6% of atmospheric water content is required since the normal pressure is about 101000 Pa. By comparison Ethane's triple point is at 1.1 Pa and -182C, so Ethane certainly condenses, despite being relatively rare. Methane is converted into Ethane by solar radiation. Now, I'm not a specialist, so I would like someone with better knowledge to review what I wrote here. --Rnbc 22:58, 2005 Feb 2 (UTC)


 * I think you underestimate your own level of knowledge. Verifying what you have just said requires more than just math; it requires a level of chemistry and physics knowledge that the typical reader (such as myself) would be unable to verify.  So I'd still feel more comfortable with an authoratative reference for this, especially if we're going to contradict NASA experts.  However, if others find your reasoning convincing, then that's fine by me.  --Doradus 17:30, Mar 24, 2005 (UTC)


 * Just out of curiousity, where did you get the amount of methane in Titan's atmosphere from? In particular, is it pre-Huygens, and is it based on the upper atmosphere?  According to this ESA website [], the concentration of methane increases nearer to the surface.  This page also claims that the main liquid on Titan's surface would be methane.  If the methane abundances are higher at the surface, it may be possible that the total of amount of methane in Titan's atmosphere has been underestimated.  In that case, near the surface, the amount of methane may be enough to rise above the tripple point.  I've been looking for an actual numerical result from Huygens, though no success so far. (There is also the question of how sensitive the triple point is to impurities.  By adding some salt to water, for example, the freezing point can be lowered; could some minor impurities lower the amount of partial pressure needed enough for methane to condense on Titan's surface?) The Reflection 00:42, 25 Mar 2005 (UTC)


 * I got the methane concentration in the atmosphere from this article itself I think. It's 5% now... well, that 6% figure came from somewhere. The triple point itself is not sensitive to impurities, AFAIK, althought impurities greatly accelarate condensation below the triple point, of course. The other figures came from wikipedia also. Yes, it all smells a bit fishy to me... Still, no one has spotted any ocean there... --Rnbc June 30, 2005 01:06 (UTC)

Here's a link to a better picture of the titan "shoreline." I'm not sure if it's in the public domain:

http://www.donaldedavis.com/2005%20new/TITNAIR.jpg
 * the guy of that site puts an (c) for copyright but the images he uses cant be copyright and arent his... --Pedro 10:40, 14 August 2005 (UTC)

Regarding methane liquid on Titan. There are a few other points to note. 1st dynamics, in Titan's colder upper atmosphere liquid methane is stable so clouds and/or raindrops can form. They would then begin to fall and as they reach the warmer lower atmosphere they would begin to evaporate, however, it takes a finite time for the raindrop to evaporate and the raindrop may hit the ground before it fully evaporates. 2nd a liquid evaporates when the atmosphere around it is not saturated (the saturation point is defined as the point where rate of condensation=rate of evaporation). On Titan's surface saturation occurs at around 9% so pure methane would evaporate (given enough time) however if there are some impurities(such as ethane or other hydrocarbons present on Titan) dissolved in the methane then they can reduce the saturation value by making it harder to evaporate methane from the mixture and easier to condense it. This is smilar to syrup on Earth. The water will never evaporate from the syrup (or at least take a very long time) because the sugar makes it easier for water vapour to condense and harder for it to evaporate, reducing the saturation point. Phil Rosenberg

Magnitude
Is the magnitude mentioned Apparent or Absolute? Just wondering...

The magnitude is apparent. For the absolute magnitude (using the definition for planets, not stars), I get something around 3. The Reflection 04:15, 22 Mar 2005 (UTC)

WikiProject Fact and Reference Check
Some useful sources for this article:
 * http://www.nasa.gov/mission_pages/cassini/media/cassini-0703.html
 * http://saturn.jpl.nasa.gov/science/titan.cfm
 * http://saturn.jpl.nasa.gov/science/titan-atmosphere.cfm
 * http://saturn.jpl.nasa.gov/science/titan-surface.cfm
 * http://www.solarviews.com/eng/titan.htm (Is this a usable source?????)
 * http://www.esa.int/SPECIALS/Cassini-Huygens/

Some more sources: JesseW 22:08, 29 Mar 2005 (UTC)
 * http://huygensgcms.gsfc.nasa.gov/Titan.htm - physical data, mainly.

Another is http://nssdc.gsfc.nasa.gov/planetary/factsheet/galileanfact_table.html. Which is also mainly physical and orbital data. The data there is slightly different (Looks like entirely due to significant digits or rounding) from what is in the article. Does anyone know where the data in the article's table is from? It seems we can add footnotes to every physical fact in the table to this NASA site. I also don't know how to format that as a reference. Any ideas? - Taxman 17:46, Mar 30, 2005 (UTC)


 * Just put it as a footnote from the table section headings. Mozzerati 20:21, 2005 Apr 1 (UTC)

This article is no longer the biweekly special article for WikiProject Fact and Reference Check. In the two weeks that it was, this article got 22 references! -Frazzydee|&#9997; 18:10, 13 Apr 2005 (UTC)

I love the work done on this article! Look at all the facts that were referenced. Wikipedia might become the most verified and authenticated source of information ever created. It is very exciting, and even if someone can only do one fact reference it is an effort well worth the trouble :)). --ShaunMacPherson 21:37, 16 Apr 2005 (UTC)

Errors
A positive consequence of referencing facts in an article is that it is easy to spot errors. Below is a list of errors found by the Fact and Reference Check team.


 * Saturni Luna: I believe that Titan was called Luna Saturni, and not Saturni Luna when first discovered. There's a NASA site and a book reference on the article page.  There was one PDF file (titled 'mythology of titan') that claimed it was 'saturni luna', but a google search seems to show more for luna saturni.  Also, another NASA page writes it as Luna Saturni, and a published book also has it as Luna Saturni. I think it's fairly safe to say that Wikipedia was wrong, but please correct me if you disagree, because the answer is not completely clear. -Frazzydee|&#9997; 05:23, 31 Mar 2005 (UTC)


 * Without disagreeing, it's worth noting that in Latin it doesn't matter which way round the words go, so astronomers could have used either name without being 'wrong'. The Singing Badger 17:13, 1 Apr 2005 (UTC)

Featured article?
I think with a few minor changes this is a good featured article candidate. Just a suggestion&mdash;something to consider for the people who have been editing this article (and editing it so well). Hydriotaphia 13:24, May 11, 2005 (UTC)

Discovery of the atmosphere
Some sources say that Titan's atmosphere was "discovered by [Josep] Comas i Sola in the early 20th century", namely at 1908. Has somebody more info about this? --surueña 14:44, July 12, 2005 (UTC)


 * I just worked on this article today for the Portuguese language pt:Titã (satélite),and I used the English, Spanish and French wikipedias, and other sources: paper and internet. And the Spanish wikipedia was the only with that info - so I didn't include it. And I've investigated history, because there's not a lot (relevant). The English language article exaggerates on the Kuiper findings, although he appears a lot, but not with this importance. He discovered an atmosphere of Methane. Voyager discovered a dense atmosphere of nitrogen, it's different. This last reasoning is the one I used. BTW in the English article, there are many facts contradicting facts (lakes namely)... the Spanish and the French language are the most developed. Although the Portuguese language one is now the best. IMO :P -Pedro 19:28, 13 August 2005 (UTC)


 * We have an article on him at Josep Comas Solá, and he is sometimes referred to in the literature as "José Comas Solá". Those variations of his name will probably get you more Google hits. -- Curps 21:19, 13 August 2005 (UTC)


 * As far as I'm aware Comas Sola observed Titan and noted in his sketches that Titan was dark around its edge. This is an effect called limb darkening and is caused by the atmosphere beeing deeper (with respect to the observer) at the edge compared to the centre. Other astronomers could not, however, confirm his findings and they were not widely accepted. In 1944 Kuiper took a spectra of Titan and found the signature of gaseous methane, confirming an atmosphere existed and in the years prior to the Voyager I encounter it was argued that the dominant gas could be as yet undetected nitrogen with the methane as a lesser constituent. Voyager 1 proved this to be correct and also raised the possibility that another component with a molecular mass larger than nitrogen may be present. The favoured candidate for this component was argon because it is fairly common in the solar system and not easily detected. The Gas Chromatograph Mass Spectrometer on Huygens in 2005 measured the abundance of methane at 1.6% of the total with the rest nitrogen and only trace amunts of argon and other gases.

Is Titan still Saturn VI
Is Titan still Saturn VI? even with the discovery of new "moons" (a.k.a. debris) around Saturn? Where I can get a full listing with all this kind of numbering moons... ---Pedro 05:08, 13 August 2005 (UTC)


 * It's here: Saturn's natural satellites


 * thx. -Pedro 14:10, 13 August 2005 (UTC)

Rover mission
I'm using this article to expand the Portuguese language one, and I was thinking... is there any plan by NASA or ESA to send a rover to Titan like those on Mars? I'm just reading doubts and more doubts... It is a very interesting planet. My fav. :) Those rovers on Mars are so successful...--Pedro 14:10, 13 August 2005 (UTC)
 * I'm sure someone is thinking about it but as far as I know there's nothing planned yet or even on the drawing boards. Would be cool, though. --  Etacar11   14:17, 13 August 2005 (UTC)
 * There have been talks of using an "aerobot" to explore Titan. It's dense atmosphere and low gravity would make a helicopter like robot possible or possibly a blimp or balloon robot

--
 * That's nice. It is like in that documentary Alien Planet! That's a good idea, they should send at least two... -Pedro 14:56, 9 November 2005 (UTC)


 * Two problems with a rover I can see: How do you power it (I doubt solar would work, even without the clouds), and how do you prevent it from freezing solid? Do we put half a kilo of plutonium in it? kwami 20:48, 9 November 2005 (UTC)


 * The fact that only a few square meters of titan's surface have been imaged in detail, and that those pebbles of ice would severly impede any hypothetical rover's wheels, means that at the very least, detailed reconaissance of the surface from a balloon or blimp in the atmosphere would be required. After we find out what the majority of the surface is like, only then would it be a good idea to start actually building a surface rover.--Planetary 07:37, 10 July 2006 (UTC)

Picture.
Whats with the crapy picture you chose for the main picture? there are better pictures now that Cassini is there. I order (kidding) someone to change that picture....maybe I'll find one myself.Nick Warren 16:09, 16 December 2005 (UTC)
 * Go for it! But read the discussion about false color images, at the top! Awolf002 16:47, 16 December 2005 (UTC)

Geology
This article could use revamping based on results from RADAR, VIMS, Huygens, and ISS WRT to the geology of Titan. Much of the information on the surface dates from the early encounters or early news articles on the Huygens landing. I propose revamping the "Overall Topography section and turning it into a geology section, much like the way the Enceladus article is organized. I leave to others to work on the atmosphere section.

This new Geology section would follow the atmosphere section. It would consist of the following sub-headings:


 * General Geology
 * Bright-dark terrain
 * Latitudinal variations
 * Impact craters
 * Liquids on the surface
 * Possiblity of liquids
 * Fluvial erosion (channels, shoreline, from RADAR)
 * Cryovolcanism (based on the current hotbeds section)
 * Aeolian landforms
 * Tectonic landforms

The section not addressed in all this is "Features at the Huygens landing site". I propose that a seperate article be written on the landing site itself and the general area as seen from Huygens.

Volcanopele 20:30, 11 January 2006 (UTC)
 * After not dealing with this article too much, I have now begun to transform the Physical Characteristics section to something resembling the above outline. I'm not going to follow this exactly, but it should look similar. For now, I have rearranged some text, but haven't really added too much, yet.  But you can kinda see what I have in mind. --Volcanopele 18:36, 20 July 2006 (UTC)
 * Barring any unforeseen happenings tomorrow, I'm going to try to clean-up this article. After reading through it this evening, it definitely needs it. --Volcanopele 05:06, 13 October 2006 (UTC)

3.5MB animation
Please someone remove the 3.5MB animation, as it delays loading of the rest of the page. It would be OK to have it as a linked resource, or as a still image.
 * Done. Sign you comments with ~ . --JamesHoadley 19:27, 2 March 2006 (UTC)

Source for atmospheric methane
The source of methane in Titan's atmosphere may have been found. See this link. Interesting read, could be implemented in the article.--Jyril 17:56, 2 March 2006 (UTC)
 * great, thanks a lot! the pic would be nice in wikipedia :[ very illustrative --Pedro 20:07, 2 March 2006 (UTC)

Images
What I don't understand is why the images taken of the surface so low-resolution and in black and white?

This page claims that it is taken in Titan's atmosphere, but why is it in color and in great detail? http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1512

--vex5 05:48, 10 March 2006 (UTC)


 * If you are referring to the Huygens images, the probe's camera having no filters could not take color images. Additionally, Huygens' bandwith was so limited that the images had to be compressed considerably. In the case of Cassini, Titan's atmosphere is opaque to visible light. The surface is visible only in infrared light. So no realistic color images can be taken of the surface. Although some surface features can be seen through the atmosphere, smaller details are lost due to haze even in the wavelengths Cassini camera uses. Cassini's VIMS can see clearly through the atmosphere in longer wavelengths, but it has very limited resolution. Cassini's radar has the best resolution, but radar images have nothing to do with visual or infrared light images (that is, the radar brigth or dark areas doesn't have to be bright or dark in visible light).--Jyril 16:33, 10 March 2006 (UTC)


 * I'm no expert on space probes, but I don't understand why it would be so difficult to implement a hefty flash memory device that would take high-resolution pictures, if not full scale color videos and simply transmit them to the satellite, just as the satellite transmits them back to Earth? --vex5 23:44, 10 March 2006 (UTC)


 * Earth-orbiting satellites are a bit closer than Cassini. It requires a lot more energy to send data from the distance of Saturn. Still, although the probe could probably send a lot more data, but nobody can listen it. The Deep Space Network which receives Cassini's data must also share its time with other probes. For example, in the case of Magellan Venus probe, lots of collected data was lost because it was not possible to receive it all.--Jyril 09:41, 11 March 2006 (UTC)


 * Don't know, if you ask me, I just think that a lot of time and effort is not properly assigned. I mean, how much more difficult could it be to produce images that are a little better than washed out 200 pixel black and whites? Billions of dollars at work and we get photographs of some pebbles that we can't make out. --vex5 01:26, 12 March 2006 (UTC)


 * It should be noted that the fact that Huygens had any camera at all is because 1: It had to be made very small, 2: It had the survive the firce conditions, which at the time of design were completly unknown, and 3: The public wouldn't care if all they saw was squiggly-line graphs and spectra, which are only intresting for scientists. Look at why the Jupiter probe carried by the Galileo spacecraft had no camera, it wouldn't have seen anything but random pretty pictures of clouds, and no one hears anything about it's scientific discoveries (Except the scientists). Photographs of Jupiter's "surface" i.e. cloud tops, weren't thought to have as much scientific output as the spectrometers, interferometers, and other such things, and thus a camera wasn't included. Don't forget as well, that Huygens carried 5 other instruments then just the camera.--Planetary 07:51, 10 July 2006 (UTC)
 * I read that the dense atmosphere prevents light from passing through to the surface, so could someone tell me where the shadow in the pebble picture comes from since it's obviously not from a "flash" from the probe since the lightsource is seemingly from the top left of the photo?--Bas 05:05, 12 September 2006 (UTC) —Preceding unsigned comment added by 66.36.135.116 (talk • contribs)
 * On a clouded day if you look up and try to find the sun you will not find it because the direct light is scattered in the optically dense clouds. The same on Titan. An all other planets and moons except Venus and the gas giants you see the sun!--Stone 15:49, 12 September 2006 (UTC)

Sand Dunes
Someone needs to rewrite the sand dunes part. It does not look like an encyclopaedia article.--DIGIwarez 03:25, 5 May 2006 (UTC)


 * It also needs a cite to who had made the analysis. Ashmoo 06:52, 17 May 2006 (UTC)


 * I worked at it a bit, it is basically right from what I remember, but didn't do a detailed check on the referenced articles in the Science or space.com. It did say that scientists had previously thought dark regions were Ethane seas filled with sand, but I think they just thought the dark areas were Ethane seas period/full-stop, so I removed that bit.
 * I also moved the section up to below Titan (moon), just because it seems a better layout. --JamesHoadley 10:58, 17 May 2006 (UTC)


 * Could someone who knows please indicate which image shows terrestrial dunes and which Titanian? Pinkville 13:47, 14 June 2006 (UTC)
 * The top image in that figure shows dunes in Namibia while the bottom image shows dunes on Titan. I've changed the caption to indicate this. --Volcanopele 15:42, 14 June 2006 (UTC)
 * That's great. Much better. Pinkville 16:11, 14 June 2006 (UTC)

What is meant by "bulk properties" ?
The term "bulk properties" appears at the beginning of the second paragraph in the Physical characteristics section. What does it mean? -- Run! 14:02, 2 June 2006 (UTC)


 * It just means the percentage of elements and basic molecules/minerals in the body. Two bodies could have the same bulk properties but be very different, because the elements are arranged differenly within the body, or the temperatures are different. -- JamesHoadley 10:04, 3 June 2006 (UTC)
 * Hmm. The reason is ask is that the first sentence says, roughly:
 * Titan is similar in bulk properties to Ganymede, Callisto, Triton, and (probably) the planet Pluto.
 * And the last sentence says:
 * Though similar in composition to Rhea and the rest of Saturn's moons...
 * And this seemed to imply that something different than composition was meant in the first sentence. I think this needs clearing up. -- Run!  16:37, 3 June 2006 (UTC)

Astronomy Collaboration of the Week
Nominated for Collaboration of the week --Volcanopele 21:55, 5 June 2006 (UTC)

Lakes!
Wow! http://photojournal.jpl.nasa.gov/catalog/PIA08630 I think that seriously improves prospects of liquid on Titan? I'll add it now.--Planetary 22:04, 24 July 2006 (UTC)

I did it, but can somone please add the images in question? I'll just screw things up with the layout. --Planetary 22:30, 24 July 2006 (UTC)


 * Sweet, I added a little note in the Dark Areas section too, because before Cassini they were thought to be oceans, then Cassini found they were dunes, so that kind of completes the cycle of discover. I'll add the image as Image:Titan_North_Pole_Lakes_PIA08630.jpg. --JamesHoadley 22:43, 24 July 2006 (UTC)


 * Looks good.--Planetary 04:56, 25 July 2006 (UTC)


 * I see I'm late. :)

In case further references are needed, this article may be of use. --Xanthine 09:48, 26 July 2006 (UTC)


 * And this. --Planetary 19:51, 1 August 2006 (UTC)

Axial tilt: zero?
Can anyone provide a reference for this? It seems unlikely. Do we know this for sure or do we just not have enough data to say? DenisMoskowitz 17:06, 28 July 2006 (UTC)
 * Never mind, I now see that many (all?) of the major moons have axial tilt of zero, synchronous orbits, and <1&deg; orbital inclination from the parent equator. DenisMoskowitz 17:15, 28 July 2006 (UTC)

Contradiction?
What does this mean? "It is also larger by diameter than the planet Mercury, though Mercury is more than twice as massive." It seems like a contradiction to me


 * A basketball is larger in diameter than a bowling ball, but the bowling ball is more massive, because it has a higher density. Mercury is made of heavy elements, Titan largely of water ice, which is much less dense.--Curtis Clark 13:21, 5 September 2006 (UTC)

Surface area
Why the surface area is greather than that of Ganymede while the diameter is smaller?--Nixer 10:56, 17 September 2006 (UTC)

Well it depends on if you count the atmosphere or not. If you include Titan's atmosphere, it's larger then Ganymede.--Planetary 06:32, 9 October 2006 (UTC)


 * Titan's atmosphere doesn't exactly count as the surface. If you included Titan's atmosphere it would be the largest moon in the solar system. You can't have it half and half. I.e. you can't say Ganymede is the largest moon in the solar system but Titan has the largest surface area of any moon in the solar system. It's a contradiction in terms. That figure needs to be changed.--Just James 20:50, 9 October 2006 (GMT+10:00)


 * It appears to be correct. The Ganymede page lists its own surface area as 87 million km2 (i.e. 8.7 x 107 km2) whilst the Titan page lists its own surface area as 8.3 x 107 km2.--Just James 20:57, 9 October 2006 (GMT+10:00)