Talk:List of periodic comets

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Why is the comet Hale-Bopp not on either list? Not the numbered list, or the unnumbered list. KellyCoinGuy

See List of non-periodic comets. -- Curps 06:45, 27 Jan 2005 (UTC)

Contents 1 Why? 2 Non-numbered periodic comets 3 List with red-links 4 Proposal to rename page

[edit] Why?

Why the Comet C/1861 J1 is include in the List of unnumbered periodic comets?. I mean The Comet C/1861 J1 have a revolution period of a least 400 years and only one perihelion passage and a periodic comet is defined to have a revolution period of less than 200 years or confirmed observations at more than one perihelion passage —The preceding unsigned comment was added by 200.8.148.31 (talk • contribs) 06:20, 6 June 2007 (UTC).

http://en.wikipedia.org/wiki/List_of_periodic_comets#_note-multiple

It have been observed during two perihelion passages. Comet C/1861 J1 = Comet C/1500 H1. (This was proved by I. Hasegawa and S. Nakano [1], but the comet did not recieve an official number.) --Chesnok 11:01, 6 June 2007 (UTC)

[edit] Non-numbered periodic comets

This list should be renamed to either List of numbered comets or List of numbered periodic comets, or alternatively non-numbered periodic comets should be included this list. Now the title/content is somewhat misleading as the majority of periodic comets is missing.--Jyril 22:48, 21 December 2005 (UTC)

Can you provide an example for a missing comet? This list is taken from the official page at the IAU (See "External links"). AFAIK, there are no other officially recognised periodic comets. Awolf002 22:58, 21 December 2005 (UTC)

That list include only numbered periodic comets, which have been observed longer than over one orbit. Here's a list of comet discoveries made in 2005: [2]. As you can see, there are several periodic comets.--Jyril 10:10, 22 December 2005 (UTC)

I agree that there seems to be some ambiguity in the definition of periodic. Here is a part of the IAU resolution text [3]:

3. The nature of an object can further be indicated by an initial prefix. In particular, such prefixes should be applied in cases where comets have possibly been misdesignated as minor planets, or vice versa. If necessary, the prefix A/ would precede a comet designation that actually refers to a minor planet (or asteroid). For comets the acceptable prefixes are P/ for a periodic comet (defined to have a revolution period of less than 200 years or confirmed observations at more than one perihelion passage) and C/ for a comet that is not periodic (in this sense), with the addition of X/ for a comet for which a meaningful orbit can not be computed and D/ for a periodic comet that no longer exists or is deemed to have disappeared.

4. If a comet is observed to return (or have its periodicity established by observation through aphelion or from identifications), the P/ (or D/) shall be preceded by an official sequential number (e.g., 1P/1682 Q1 = Halley), the list to be maintained by the Minor Planet Center and published in the Minor Planet Circulars. Subsequent recoveries shall be acknowledged with further designations only when the predictions are particularly uncertain.

I read this as: Use P if the orbit is found to be elliptic with a period of less than 200 years, but only put it into the number periodic list if confirmed by second perihelion, or identifications of previous apparitions, or if the observations span the current aphelion. So, this article represents the numbered periodic comet list, I guess. Comments? Awolf002 19:26, 22 December 2005 (UTC)

[edit] List with red-links

I see that the unnumbered periodic comets are now part of this page. That may be fine (as discussed above), however I feel nervous about all those red-links set for all those comets. I do not believe that each and everyone of them is notable enough to warrant an article! Can we agree to remove the red-links, and only add article links, when there is something to write about and an article exists? Awolf002 12:36, 1 February 2007 (UTC)

[edit] Proposal to rename page

I've made a few comments on various comet-related pages about this issue. IMO defining "periodic comets" as comets with a period of less than 200 years is extremely confusing. Comets with periods of > 200 years are just as "periodic". I understand that some authorities use this terminology, but others seem to use the more sensible term "short-period comets". I think in Wikipedia we should lead with the term "short-period comets", and mention parenthetically that some use the term "periodic comet" instead. To this end I suggest that this article is renamed "List of short-period comets". Any objections? Matt 22:02, 25 December 2007 (UTC).

Object: As you correctly write, a periodic comet is only called periodic when the period is lower than 200 years, as defined by official agency assigning the title periodic (prefix P). This list represents those comets and as such should be called in way that does not conflict with that definition. (If you want to quibble with the reasoning why these are called periodic, that would be another type of discussion.) Just my 2 cents. Awolf002 (talk) 00:56, 26 December 2007 (UTC)

Hi again. No, I don't want to quibble with any official definitions. If the astronomical community calls them "periodic comets" rather than "short-period comets" then we should clearly use that term. But per my comment at Talk:Comet#Confusion/contradiction I think that if we must stick with calling them "periodic comets" then an explanatory note for the non-specialist is necessary to allay the reader's fears that a mistake has been made. I first looked at these two articles -- List of periodic comets and List of non-periodic comets -- ages ago, and just assumed that there was just some Wikipedia-specific muddle and confusion about terminology, or the article started out as one thing and then morphed into another, or something like that. It's only recently that I've spent a bit of time looking into it that I've finally figured out what's going on. Matt 03:17, 27 December 2007 (UTC). —Preceding unsigned comment added by 86.136.194.71 (talk)

For now I have just put some more explanatory text into the opening paragraph. Matt 20:33, 28 December 2007 (UTC). —Preceding unsigned comment added by 86.142.111.76 (talk)

Looks pretty good to me. Hopefully, this will point readers the "right way" and remove the confusion. Thanks! Awolf002 (talk) 21:05, 28 December 2007 (UTC)