Approaching asteroid? Is this THE one?
Helio, "The Earth–Moon system is the unique exception " - for a start.
Well, songs do pretty well.Helio, as you may know, I am a Korzybski fan. Names are not realities - they are vibrations in the air or marks on paper. They are useful if we remember that.
Agreed, the rule is to wait a while before breaking them.What is the point of making a rule, if the first thing you do is break it.
Well, Percival Lowell was the closest person this side of the pond in comparing to your Herschel. So part of the naming is due to honoring his name.Pluto was named a planet in error, because it happened to be the first rock they found beyond Neptune. I sometimes wonder what they would have called it, had it been inside Neptune's orbit at the time?
No. Think of a see-saw. No matter how thin the heavier person is on one side, the fulcrum will always be closer to that person.Are there, as a matter of interest, any binary planets where one is 'infinitely'' ( ) massive but very small, such that the cog or barycentre (is it?) is between them but closer to the smaller body?
Well, if their barycenter is in space between them, then one should be able to call them a binary system if it somehow serves a pedagogical purpose in using that term. I think most don't bother doing so since a "dwarf binary system" starts to be a mouthful -- more "vibrations", as you may say, and normally not that substantive.My point was, do you still call them binary planets. You can call them binary see-saw participants if you like. I don't see the relevance.
I think moons do clear their orbits, if I understand your direction here. Are there any moons that have the same orbit? I know there are some moons that come close, one pair even swap orbits when the inner orbiting moon catches the outer one.You can see where the nomenclature trips over itself. You can have a binary dwarf planet system with 5 (or 4) moons. Why should moons not be cleared? or even binary (dwarf) planets. What does need to be cleared. Obviously not satellites or trojans (small t).
Agreed. We even give names to hypothetical planes (e.g. Vulcan) since every headline needs to add such things to gain prominence. Numbers for an object have little to no sizzle.All I am suggesting is, that you can name things what you like on the basis of convenience, but you can change categories (labels) as circumstances change.
Initially, the Earth’s orbit had millions of fellow orbiting bodies, primarily planetismals. The mass of Earth is such that it’s impossible for smaller bodies to not be tossed. The laws of gravity are reliable enough to establish what mass is great enough for any given orbital distance. Even Trojans are temporary.Planet definition is rather silly IMO.
No planet in our solar system really clears out it's orbital path.
Earth gets bigger many tons a day still clearing it's.
Well, the guesses suggest something might be there, else why bother?When it comes to objects which aren't there, I suppose guesses can get a little fragile.
A better definition of planet i think is needed.Initially, the Earth’s orbit had millions of fellow orbiting bodies, primarily planetismals. The mass of Earth is such that it’s impossible for smaller bodies to not be tossed. The laws of gravity are reliable enough to establish what mass is great enough for any given orbital distance. Even Trojans are temporary.
The use of clearing an orbit does appear as an ad hoc measure just to force a limit on the no. of planets. Many agree with you, but I prefer to not see hundreds of new and unnamed planets slowly accumulate on a long list, all small objects but massive enough to be round.Helio, I just think that this 'clearing orbit' condition is non-sensical.
Ah, that makes sense. Thanks. It’s amazing that Jupiter hosts over 8,000 Trojans (L4 & L5).You can't demote Jupiter because it has Trojans (capital - because they were originally so named). Thus Jupiter has trojans specifically called Trojans. No other planet can have Trojans, only trojans.
Agreed. It is worth the tiny effort to present a rough size by using a simple label, or labels. ”Moonlets” (unround ) might be a fair synonym for satellite, avoiding the artificial connotation, when applicable.Perhaps Mars' Deimos and Phobos should be called satellites instead of moons, since they were possibly just captured bits of junk. Maybe there should be a lower limit to the term moon, perhaps sphericity. I think this is often implied anyway.
Totally agree. Needs a bullet proof definition.VPE, "Clearing an orbital path never really happens for any planet."
Generally, I agree with you completely. All sorts of other sub-conditions have to be attached to cover eventualities including moons, trojans etcetera. Then do you apply the same rules to dwarf planes?
If so, what happens when a planet or dwarf planet acquires satellites like Charon, Moon, across to Deimos and Phobos.
Incidentally the remnants we know as Mercury and Venus are the result of orbit clearance. Impacts caused proto-Mercury to loose a lot of its mantle, and caused proto-Venus to rotate (just) in the opposite direction.
The point I am making is that any rules should be made foolproof so that a status is not changed if, for example Mercury or Venus were to acquire Mars's sized (D and P) satellites. If you robbed Mars of planetary status because it did not get rid of D and P, then Venus would lose planetary status if it acquired a 'comet' (or post-comet remnant) or an asteroid as a satellite. So, you have to allow satellites (so the rule does not change), but what about trojans (small 't')?
Maybe a moon should also be a sphere or be called a moonlet if it's not.Helio, "Maybe there should be a lower limit to the term moon, perhaps sphericity."
I was referring to moons, not planets. My views about planets are as I believe to be current nomenclature. I am not a Pluto worshipper. There are 8 planets. Below that there are dwarf planets.
When it comes to moons (which I was talking about) sphericity may be a criterion? I am talking about sphericity of moons. I have no objection to moonlets and then 'junk'.
You also posted: "Many agree with you, but I prefer to not see hundreds of new and unnamed planets slowly accumulate on a long list, all small objects but massive enough to be round."
In fact you implied that I differed from your opinion, whereas I did not, since my 'sphericity' applied in context to moons. The second para was only about moons/satellites.