New moon discovered at Pluto

[Saquist]

You've been lied to.

As far as I'm concerned that could be a confession.

Science usually is.

That's theory.

When it is large enough to pull itself into a sphere.

Not according to the definitino.

First of all, the planets weren't the ORIGINAL dominating stellar accretions, but the FINAL ones.

We don't know that.
And that's not the point.

Second of all, NONE of the planets have a zero inclination, all of them are slightly inclined above or below solar zero.

No one said they had zero inclinations.

Actually, it is based on MASS. That is to say, a dwarf planet is a planet that has NOT cleared its neighborhood of other massive objects. Again, Earth would be a dwarf planet if it shared an orbit with Venus and Mars.

Again Jupiter...

Because it isn't about size, it's about MASS. A ten ton object that shares its orbit with two dozen one-ton objects is NOT the dominant body in that orbit.

Firstly it is dominant.
Secondly then every planetary satellite system is a dwarf planet.

It doesn't matter if that object is the size of a house or the size of a mouse, if it's the size of a box or the size of a fox. If it doesn't have the majority mass, then it is a dwarf planet.

It makes absolutely no sense at all.

 

[Pavonis]

So, a planet should be an object of a particular size that orbits the Sun? That's it?

 

[YellowSubmarine]

I'd personally go with:

satellite - an object that orbits another object
planetoid - a satellite of a star that is not a star
planet - a planetoid that is gravitationally dominant in its neighbourhood, or one of binary planetoids that are gravitationally dominant in their neighbourhood
moon - a satellite of a planetoid or a moon
major planetoid/moon - a planetoid/moon that has achieved hydrostatic equilibrium
minor planetoid/moon - a planetoid/moon that has not achieved hydrostatic equilibrium

So:
- planets remain planets
- all planets are also major planets
- dwarf planets become major planetoids (but planets are also major planetoids)
- asteroids become minor planetoids (although you can imagine minor planets that probably don't exist)

Or something similar with other words. Maybe also replace “major” with “dwarf” and “giant” to separate between gas giants and the other planets, so that the Earth becomes a dwarf planet, and introduce another word for “minor”.

 

[Pavonis]

Why should Earth be classified as a dwarf planet?

 

[YellowSubmarine]

No particular reason other than consistency with dwarf/giant star. But the split into three categories (minor, dwarf/regular, giant) doesn't make that much sense now that I think about it, splitting it into major and minor is enough.

 

[Pavonis]

Still not clear why Earth should be a "minor" planet.

 

[YellowSubmarine]

Still not clear why Earth should be a "minor" planet.

No, no, no, it shouldn't be minor. I only propose that asteroids become minor planetoids, dwarf planets become major planetoids and planets become, well, planets (and major planets as well), and that moons follow the same minor/major classification. The “dwarf” thing was only an idea about how to fit gas giants in, and it felt consistent with the ways stars are classified.

 

[Pavonis]

... so that the Earth becomes a dwarf planet, and introduce another word for “minor”.

Huh?

 

[YellowSubmarine]

I meant:

replace “major” with “dwarf” and “giant” [...] and introduce another word for “minor”.

Like baby planetoid, dwarf planetoid and giant planetoid. Or something.

 

[Pavonis]

Calling Earth a dwarf planet would clarify things for you?

Are you sure you understand how and why stars and galaxies are called dwarf?

 

[YellowSubmarine]

The only reason I suggested this is because with the definitions I proposed above you'd have overly long names like “giant major planets” (well, not really), and you have no name for non-giant planets, so for a second I thought that you could simply split “major” into “dwarf” and “giant” and drop the “major” label, but as I already said that on a second thought this doesn't really make that much sense and doesn't lead to any improvement, so the “maybe” in my original post can now be read as “maybe not”.

Hey, when I say “maybe [something]”, I do not mean “most certainly [something]” or “[something] is the greatest idea ever”.

 

[Crazy Eddie]

Science usually is.

That's theory.

No, that's nomenclature.

Not according to the definitino.

Yes, according to the definition. That's what "hydrostatic equilibrium" means. For an object to be considered a planet OR a dwarf planet, it has to be massive enough to form itself into a sphere.

We don't know that.
And that's not the point.

Yes we do. And if it isn't the point, then you shouldn't have brought it up in the first place.

No one said they had zero inclinations.

You did.

Again Jupiter...

... is several thousand times more massive than all the other objects in its orbital neighborhood COMBINED. That is gravitational dominance to the extreme condition.

Because it isn't about size, it's about MASS. A ten ton object that shares its orbit with two dozen one-ton objects is NOT the dominant body in that orbit.

Firstly it is dominant.

No it isn't. Because the majority of the mass along that orbital neighborhood is distributed among the OTHER objects in that system, whose SUM influence on that singular object is greater than its influence on any one of them. This is not the case for any of the major planets.

Secondly then every planetary satellite system is a dwarf planet.

Not unless the satellite's mass is more than 50% of the mass of the primary, in which case it would classify as a "double planet" or "binary planet," NOT a dwarf planet. Pluto, if you recall, was almost classified as a double planet twenty five years ago until more accurate measurements could be taken of its mass and the mass of Charon.

It doesn't matter if that object is the size of a house or the size of a mouse, if it's the size of a box or the size of a fox. If it doesn't have the majority mass, then it is a dwarf planet.

It makes absolutely no sense at all.

It makes sense to astronomers. You're welcome to try and convince them that they are wrong and that it doesn't actually make sense to them after all.

 

[Crazy Eddie]

The only reason I suggested this is because with the definitions I proposed above you'd have overly long names like “giant major planets” (well, not really), and you have no name for non-giant planets, so for a second I thought that you could simply split “major” into “dwarf” and “giant” and drop the “major” label, but as I already said that on a second thought this doesn't really make that much sense and doesn't lead to any improvement, so the “maybe” in my original post can now be read as “maybe not”.

Hey, when I say “maybe [something]”, I do not mean “most certainly [something]” or “[something] is the greatest idea ever”.

So in order to avoid using "dwarf" sub-label you instead invent five other labels and resurrect an outmoded one?

I'm beginning to realize that despite all your passion and fury about the definition of "planet" you don't actually know anything about astronomy.

 

[YellowSubmarine]

Sorry, I almost forgot that astronomy forbids simplicity, consistency, non-confusing choice of words and other old-fashioned things.

 

[Crazy Eddie]

Sorry, I almost forgot that astronomy forbids simplicity, consistency, non-confusing choice of words and other old-fashioned things.

That's okay, lots of people forget that. Especially people like yourself who don't know much about astronomy and aren't familiar with the annoying fact that most objects in astronomy--including Pluto--fall into a SEVERAL different categories at any given time, of which "dwarf planet" is merely the least complicated to explain.

 

[Cmdr_Blop]

Always good to hear news from the 9th planet.

 

[Gepard]

Pluto has some strong feelings on the matter.

 

[Cmdr_Blop]

Goat had it coming.

Just saying...