Talk:Chthonian planet

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Does anyone know anything about the source of the name "Cthonian"?

Or furthermore, the difference between "Cthonian" and "Chthonian"? Laguna72 17:47, 27 Nov 2004 (UTC)

Google got me: greek kthon or xthonos which literally means 'dweller under the earth'., which sounds about right given the definition of the gas giant being stripped away to leave the core. Can someone confirm? -- Tarquin 13:17, 9 Jan 2005 (UTC)
Are there any confirmed cases of the use of "Cthonian", which is essentially a mistake?
Urhixidur 02:51, 2005 Feb 11 (UTC)

Mercury a former Gas Giant?[edit]

The article currently states that "Some scientists suggest that Mercury is a Chthonian planet due to its high density and metal-rich core", this seems like quite a bizarre view and I've certainly never heard of this theory of Solar System formation before. It needs to be stated who these some scientists are, so I've added a Citation needed tag to the sentence. --Hibernian 18:54, 9 March 2007 (UTC)

Bizarre, yes. As much as I know, the scientists believe that Neptune have an earth sized core of rock and other heavy stuff. If it is really believed, then the believers must believe that a lot of rock must have evaporated from the Jovian Mercury after the atmosphere was removed. The Sun must have been hot indeed! Or Mercury a very puny tiny little Jovian, if such can be imagined... Said: Rursus 21:23, 27 June 2007 (UTC)
I cannot find support for it on the Internet. It's probably some kind of confusion. Time to remove. Said: Rursus 21:57, 27 June 2007 (UTC)
Also keep in mind the scientists suspect that Mercury may have suffered a large impact that removed most of the outer layers... -- Kheider (talk) 13:37, 13 June 2009 (UTC)

Mars, Not Mercury - How does this differ from Mars? Most of its atmosphere has been depleted by the sun. I realize this is a stretch, as Mars is definitely a terrestrial planet. Just a though. (talk) 23:19, 16 November 2016 (UTC)


Please add a spelling (sound) link to the name.--Mazarin07 19:47, 7 May 2007 (UTC)

I too am curious to the pronunciation of this word. I would assume /ˌkθon iən/ or perhaps /ˌxθon iən/, but both of these are difficult for English speakers. Maybe just /ˌθon iən/?
Well, I found Chthonic, which seems to say that /ˌkθon iən/ is proper, but some Americans use /ˌθon iən/. Thus both kuh-THOH-ne-an and THOH-ne-an seem to be correct.
-- trlkly 08:59, 8 June 2007 (UTC)
Should be in the article. I'll put it there. Said: Rursus 21:33, 27 June 2007 (UTC)
Cool, but I think the alternative pronunciation should also be represented. See the above mentioned chthonic article
-- trlkly 11:54, 28 June 2007 (UTC)

HD 149026 b[edit]

How about super-Neptune / eroded-Saturn HD 149026 b. Or is this article meant for Jupiter-class coreless planets? --Zimriel (talk) 23:00, 26 August 2008 (UTC)

HD 149026b does not really fit into the "chthonian planet" class - it still retains a large amount of hydrogen, which means it is not a "chthonian planet". Also is evaporation of HD 149026b confirmed observationally or just predicted theoretically? (talk) 12:26, 27 August 2008 (UTC)


How about this planet: COROT-7b? This planet seems to be the first Chthonian planet discovered. Should we add it to this article? Maaf (talk) 02:44, 13 June 2009 (UTC)

Should the line "COROT-7 b may be the first chthonian planet discovered.[2][3] Kepler-10b is also the second chthonian planet found" read "COROT-7 b may be the first chthonian planet discovered,[2][3], followed by Kepler-10b" ? The way it is written now is a bit confusing. --Richardson mcphillips (talk) 04:32, 27 November 2011 (UTC)

internal conflict[edit]

the article states that the planet is a hypothetical class, which means not proven in term of existence. Yet at the same time claim that there have been some such planets discovered. While the term "may be" infers uncertainty, from the way the sentence is styled it appears to be an uncertainty in terms of whether it is the first one discovered(as in other planets might be discovered earlier but not realized as such a planet) as opposed to whether it is actually such a planet. If it is indeed debatable whether the listed planets are Chthonian planets, the sentence needs to be worded better. If the planets are confirmed as Chthonian planet, then the hypothetical class statement needs to be removed. (talk) 22:05, 11 July 2013 (UTC)


Is it really a chthonian planet? Due to the presence of Kepler-10c, a 42-day period planet, I think it's not possible that Kepler-10b used to be a hot Jupiter as the shortest periods of an outer companion of a hot Jupiter are about 200 days. The shortest period hot Neptunes are also above the orbital periods of 1 day, especially among those orbiting Sun-like stars. The process for outer planets migrating inward (such as the case of planets around Kepler-70 also do not apply to this system. --Artman40 (talk) 13:22, 30 January 2014 (UTC)