Jump to content

Talk:Definition of planet

Page contents not supported in other languages.
From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by 203.206.53.123 (talk) at 09:48, 20 August 2006. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Template:Featured article is only for Wikipedia:Featured articles.

Template:V0.5

archive 1

archive 2

archive 3

archive 4

Orbital period of the moon and the planet

The current article contains a paragraph that describes how any moon-planet system may be considered a double-planet. The paragraph goes on to say that "The required distance from the planet to the moon depends on the mass of the planet, and the distance from the planet to the Sun, but not the mass of the moon. If the distance from the Sun to the planet increases, or the planet's mass decreases, then the required distance between the planet and moon increases."

I disagree with the statement that the mass of the moon does not change the required distance. I also disagree with the statement that as the planet's mass decreases, the required distance to the moon increases.

The period of orbit of one body about another depends upon the mass of both bodies, as this is what determines the gravitational force between the two bodies. However, as a first approximation, the mass of the smaller body is usually considered to be small when compared to the mass of the larger, and hence the orbital period calculation, in this instance, can be said to depend only on the mass of the larger body. This is usually the case in Earth's solar system, although since the article is attempting to be general and apply to any system of orbiting bodies, the approximation may not hold true in all circumstances.

On the second point, even if we assume that the mass of the moon is small, then as the mass of the planet decreases, the gravitational force between it and the moon will also decrease. Hence, the period of the moon at that orbital distance will lengthen. Therefore, the moon could orbit at a closer orbital distance and still have an orbital speed slower than the planet's speed around the star. Therefore, the required distance between the moon and planet decreases (the article as it is written says "increases").

There is no reference for the statement in the article but the article has apparently been peer reviewed so I assume someone has checked this out, and I am interested is reading what that person(s) has to write, as I am open to a complete discussion of the dyanamics of orbiting bodies and may learn something on my part. I did not make any changes to the main article for the same reason.

D. Clippinger

I'd be interested to see this issue resolved. I've been meaning to source that paragraph for a long time (for the record: I didn't write it) but lack the knowledge of Newtonian dynamics to do so. Serendipodous 19:08, 16 August 2006 (UTC)[reply]
Drat, this means that I have to break out my physics book and figure it out. Could someone get me a reference of who added that particular change while I'm doing the math? McKay 20:31, 16 August 2006 (UTC)[reply]
His name was Tompw. Serendipodous 08:38, 17 August 2006 (UTC)[reply]

Since we already have a (featured) article on the Definition of planet, I do not see why the 2006 redefinition needs its own article. As soon as the media frenzy is over, I suggest that the latter be merged into the existing article. Nick Mks 10:25, 17 August 2006 (UTC)[reply]

  • Good idea. I've already had to revert a tag removal though, after someone found himself important enough to decide by himself that this needs a seperate article. Nick Mks 14:38, 17 August 2006 (UTC)[reply]
  • Wow, we don't have an article on the discovery of Pluto? That's a travesty. It should be created as a sub-article of Pluto and fully fleshed out. There's more than enough verifiable information on the discovery of Pluto to create a featured article. --Cyde Weys 17:08, 17 August 2006 (UTC)[reply]
  • What about Herschel's discovery of Uranus? That was a far more revelatory moment; no one even suspected that there could be a new planet in our system when he found it. And what about the kerfuffle over Neptune? 17:23, 17 August 2006 (UTC) — Preceding unsigned comment added by Serendipodous (talkcontribs)
  • Exactly the point. No one suspected new planets, so the discovery events don't have as much information / hype. They were searching for Pluto for years, and there's lots of people who tried (including PL). There's a bunch of content available on the discovery of pluto. McKay 18:37, 17 August 2006 (UTC)[reply]
  • I am familiar with WP:Point I really do think that pluto has enough information to have an article on it's discovery. The pluto article is currently too large, and look at these stats -- Google hits:
  • "discovery of pluto" OR "discovering pluto" OR "discovered pluto" 70,100
  • neptune 38,200
  • uranus 34,400
the discovery of pluto is more notable if you ask me. McKay 20:40, 17 August 2006 (UTC)[reply]
  • Of course we're serious. You don't think the discovery of a fucking planet is notable enough for its own article? Christ! That AFD would be closed in record time. And please don't go throwing around WP:POINT accusations; that doesn't even make any sense in this instance. --Cyde Weys 21:02, 17 August 2006 (UTC)[reply]
Hey hey hey hey. Don't do that.  -- Run!  07:20, 18 August 2006 (UTC)[reply]
  • Merge now. This is the page for tracking the goings-on with the IAU. The new article will be hard to find unless it is prominently link to through this page. --EMS | Talk 16:16, 17 August 2006 (UTC)[reply]
  • Merge now. The two different pages are saying the same thing in different ways - it's annoying. The Singing Badger 17:35, 17 August 2006 (UTC)[reply]
  • Merge after. It isn't August 24, so I don't see how we know if the proposed defintion actually will be the ultimate one. If the decision is different from the current article, and it's merged now, then the information will not have just been incorrent then, but for almost 2 whole weeks. Radagast83 18:48, 17 August 2006 (UTC)[reply]

Merge after the decision is made. If it is succesful, then the other artichle should be changed. If it is not succesful, it should be made into a footnote.