Talk:Minor planet

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Contents 1 asteroids 2 asteroid group 3 Asteroid? 4 Separate Asteroid Family article 5 Main belt subgroups 6 Encycolpedia or Dictionary 7 Resonance values need checking? 8 Minor planet is not the same as planetoid ? 9 Small solar system bodies 10 Planetary symbols for asteroids

[edit] asteroids

It should be made clear that when the article says the asteroids have a semi-major axis of so and so many AUs that this refers to the orbit of the asteroids and not the size of the actual asteroid. 134.173.94.191 09:26, 22 September 2005 (UTC)

"Minor planets (or planetoids) are objects in the solar system that orbit the Sun like planets, but which are smaller than planets and not counted among them. The most common types are asteroids, comets, and trans-Neptunian objects."

Actually this is not correct. Minor planet is the official term for an asteroid.

Jyril - 15 July, 2004

As Minor planets and asteroids are exactly the same, why not merge them into one document (asteroid) and just redirect from minor planet to asteroid???? Greetings, Jeffrey 129.125.6.1 10:59, 22 November 2006 (UTC)

Duh, see all the other discussions below. Also Asteroid should re-direct to Minor Planet (still the official term), not the other way. Tom Peters 16:32, 22 November 2006 (UTC)

[edit] asteroid group

I think this article should be renamed to "asteroid group" or something and "minor planet" to redirect to asteroids. Jyril 10:01, 6 Jul 2004 (UTC)

But this article covers all the groups of sub-planetary objects right out to the Oort cloud, not just asteroids. If not minor planet, then just what is the generic term for "not-planet Sun-orbiting object"? I think Wikipedia needs a summary article like this that covers all of them. Bryan 15:17, 6 Jul 2004 (UTC)

Indeed. Small body is good (see for example The Nine Planets). It would cover meteoroids and dust too. Jyril 15:24, 6 Jul 2004 (UTC)

Hang on, though. The definition you added to this article (whose "official definition", BTW? IAU?) says that minor planets include asteroids and trans-neptunian objects, which is exactly what this article covers anyway. I really don't see the need to rename or move anything. Bryan 15:31, 6 Jul 2004 (UTC)

Official in the sense that IAU uses the term minor planet instead of asteroid. Only thing I don't accept that comets are also included in minor planets here. Drawing the line between comets and asteroids is historical and far-fetched, but we should use the defined terms if possible and not invent own. Jyril 18:10, 6 Jul 2004 (UTC)

The only place comets are described as being minor planets is the line "If a minor body produces coma it is called a comet," in the intro paragraph. This does not say that all comets are minor planets, however, just that some minor planets are also comets. This seems to be supported by List of noteworthy asteroids#Numbered asteroids that are also comets, where there is a list of bodies that are considered both asteroids and comets. In Chiron's case in particular the key characteristic that resulted in its dual citizenship seems to have been the discovery of a coma. I'll add a clarifying note. Bryan 23:18, 6 Jul 2004 (UTC)

"Small body" is a poor name for an article, because it is ambiguous: it could refer to a human body of short stature. I'm also not yet convinced that we need to move the article. -- hike395 16:02, 6 Jul 2004 (UTC)

Doesn't the Minor Planet Center also track moons. Should those be part of the definition? Rmhermen 16:08, Jul 6, 2004 (UTC)

In a sense they are small bodies too, but that would make it too complicated. Jyril 18:10, 6 Jul 2004 (UTC)

Oh, as a side note, if the IAU doesn't consider comets (as a class) to be minor planets then Category:Comets should probably be recategorized (it's currently a subcategory of minor planets). Bryan 23:26, 6 Jul 2004 (UTC)

[edit] Asteroid?

What is the difference between asteroids and planetoids / minor planets? -Hello World! 04:32, 2 August 2005 (UTC)

In my opinion, nothing. Here Wikipedia however asteroids seem to exclude Kuiper Belt objects and Centaurs, which is in a way justified since if one such object wanders to inner Solar system it would be called a comet (and that's what often happen). Planetoid is a somewhat outdated synonym for an asteroid. Some astronomers have proposed that the definition of planetoid should be reassigned to refer only to the largest asteroids and Kuiper belt objects. It's a pity that term asteroid became prevalent, because planetoid ("planet-like", refers to their physical properties) is more describing term than asteroid ("star-like", because they look like stars in telescopes).--Jyril 08:49, August 2, 2005 (UTC)

If "asteroids seem to exclude Kuiper Belt objects", Does it mean that comet is a kind of planetoid? Since in Chinese language, both asteroids and planetoids are translated as "小行星" (小 means small and 行星 means planets) --Hello World! 04:46, 3 August 2005 (UTC)

• Planetoid used to be a synonym for asteroid. But with the discovery of very big TNOs, the name planetoid is incresiling used by scientists, writers, media, etc to these new objects. We know that these bigger "asteroids" are different from common asteroids. So Ceres, Sedna, Quaoar, Orcus.. are planetoids. I think we should not redirect planetoid to asteroid... other wikipedias dont do it. -Pedro 23:14, 16 August 2005 (UTC)

[edit] Separate Asteroid Family article

I'm seriously considering moving the entire part which concerns Asteroid Families to a separate article. (Including the list of families), and putting in its place a link with maybe a sentence or two. There are two reasons:

1. Quite a number of links to this article that I have encountered are just there because of the asteroid families. They are there largely because there isn't a separate article which explains the issues common to all the families.
2. A longer piece of text about the families like what I have put in today doesn't really sit well here, because this article is mostly a list of groups with only enough detail to identify what they contain.

So, i'm interested what your opinion is on this suggestion. If there is no major protest against this, I'll try to implement the move in a week or so. Deuar 22:23, 22 December 2005 (UTC)

Since there was no protest, I have carried this out. Deuar 22:06, 1 January 2006 (UTC)

[edit] Main belt subgroups

Does anyone know where the main belt subgroups with names like Main Belt IIb asteroids come from. I've never come across them anywhere else. Is there some sub-field that they are used in? Perhaps they were introduced in a paper or two, but never caught on? (they're kind-of dull...) Does anyone have a reference for them? They look like they're never going to get an article, so if no-one stands up do defend them I would certainly suggest removing the broken wiki links, and probably deleting them outright.

While i'm on this, is there a group inwards of 2.3 AU? e.g. Main Belt O asteroids? There's a heap of asteroids around there. Why did they get the short straw? Deuar 22:37, 22 December 2005 (UTC)

I haven't heard of those groups before, but it seems that the source of the article is [1] and that page cites Clifford Cunningham's book and the MPCs. - hike395 04:19, 23 December 2005 (UTC)

[edit] Encycolpedia or Dictionary

Hello. Wow, that's a lot of pages. But is it really encyclopedic? Or perhaps better suited to dictionary? e.g. List_of_asteroids, List_of_asteroids_(29001-30000), List_of_trans-Neptunian_objects, List_of_periodic_comets, List_of_non-periodic_comets. Is there a top-level page that discusses this project? Ewlyahoocom 13:54, 10 February 2006 (UTC)

[edit] Resonance values need checking?

My Solar System Dynamics book says that the Hilda family is in a 3:2 resonance with Jupiter, not a 2:3 resonance as the article claims. 3:2 makes more sense since they should be completing three orbits for every two orbits of Jupiter (for comparison, Jupiter's moon Io is described as being in a 2:1 resonance with Europa and it completes two orbits for every one that Europa completes - so the inner body should have the higher number in the x:y description, surely?).

Can someone doublecheck the resonances shown here to make sure they're shown the right way round?

Thanks! Should be ok now Deuar 22:37, 23 May 2006 (UTC)

[edit] Minor planet is not the same as planetoid ?

Minor planet is asteroid. The bodies called planetoids - the transitional bodies between planets and asteroids, which have planet-like shape and considerabl;e dimentiions, such as Sedna, Orcus, Quaoar, Xena etc. Sometimes Ceres considered planetoid.--Nixer 20:36, 5 August 2006 (UTC)

Planetoid is somewhat outdated (although more accurate) synonym for asteroid, an object officially known as minor planet. Since the discovery of large trans-Neptunian objects, Mike Brown (and perhaps others) have suggested that the name could be recoined for those almost-planet sized objects. Currently, however, the terms can be considered synonyms and no one should claim that false. Personally, I like Mike Brown's suggestion (if it's his).--JyriL ^talk 20:50, 5 August 2006 (UTC)

So why are there two articles on Asteroids and Minor planets? The articles claim that asteroids are a subclass of minor planets, but I do not believe that such a distinction is consistently made in old or current astronomical literature; besides, there is much overlap between the two articles. I propose to merge these, possibly under Small solar system body. Tom Peters 19:50, 25 August 2006 (UTC)

Asteroid is already 32 KB in size, and minor planet about half that. Merging them would result in an article that'd probably be large enough to warrant splitting again anyway. I don't believe there's much overlap in content, minor planet is mostly a big list of the various subgroupings by orbit and the asteroid article has only a single paragraph on that topic. Bryan 00:07, 26 August 2006 (UTC)

Minor Planet is under consideration for merging with Small solar system body in accordance with IAU recognition of that term encompassing everything that isn't a planet or dwarf planet. Asteroid might work as a sub-page to Small solar system body. As well as others, once the merge is done this should be revisted. --Exodio 02:25, 26 August 2006 (UTC)

[edit] Small solar system bodies

If the draft definition of a planet will be adopted, the term minor planet will be no longer used. Instead, all objects orbiting a star smaller than planets are to be called small solar system bodies. That term covers objects such as asteroids, TNOs, and comets.--JyriL ^talk 14:21, 16 August 2006 (UTC)

Is there a difference in definition of asteroids and TNO's? I don't think so. The Centaurs for example are most likely very similar to SSSBs beyond Neptune, but by definition they are not TNO's; OTOH they are unlike the rocky major-belt asteroids. Tom Peters 15:11, 26 August 2006 (UTC)

Using planetoid would've made life so much easier... I wonder why they didn't? 132.205.93.195 21:17, 16 August 2006 (UTC)

The term seems to have been adopted happily by the IAU. I've created a stub; probably worth bulking it out quickly. Shimgray | talk | 16:43, 24 August 2006 (UTC)

Why a stub? The term used here includes asteroids and comets, exactly the same objects. Just a page move should have been enough.--JyriL ^talk 17:53, 24 August 2006 (UTC)

There's a total lack of evidence that the IAU intended the term SSSB to replace "minor planet". The status of the term "minor planet" isn't addressed in the IAU's resolution. IIUC "minor planet" is anything that the Minor Planet Center assigns numbers to: asteroids, centaurs, trojans, TNOs. SSSB includes most of these (per resolution) + comets and meteors.RandomCritic 08:31, 28 August 2006 (UTC)

The problem is this: If minor planets are considered as asteroids (like the IAU unofficially does), this page is redundant, but if the term "minor planet" include asteroids + comets + TNOs (like has been done here) this page is again redundant (because SSSB ~ minor planet).--JyriL ^talk 20:50, 28 August 2006 (UTC)

The IAU officially uses the term "minor planet" as you yourself pointed out, and according to Brian Marsden that is synonymous with "asteroid". That does include TNO's (moving specks of light without a coma that happen to orbit beyond Neptune) but excludes comets (moving specks of light with a coma that they usually develop within the orbit of Jupiter). So actual and current terminology among astronomers is that "Minor planets" are not synonymous with "SSSBs" but are synonymous with "Asteroids", so we should not merge "Minor planets" with "SSSBs" but with "Asteroids". Tom Peters 23:27, 28 August 2006 (UTC)

That's how it should be. Nobody has provided any evidence that comets are classified as minor planets. The contents of the minor planet article should be moved here, and redirect should be pointing to the asteroid article.--JyriL ^talk 16:22, 31 August 2006 (UTC)

There's a practical problem with this currently, in that when discussing physical characteristics, the asteroid article talks almost exclusively about rocky bodies that lie within the orbit of Jupiter. Deuar 10:50, 1 September 2006 (UTC)

[edit] Planetary symbols for asteroids

According to [2] there are other minor planet planetary symbols around, we should probably add it into the text (but not infobox) of the various asteroids concerned. 132.205.93.19 03:01, 25 August 2006 (UTC)