Is Pluto a planet? (Pluto discussion thread, if there isn't already one)

[RCgothic]

On 7/16/2021 at 6:31 AM, sevenperforce said:

 

• Comet. Any object in orbit around a stellar object or stellar binary, other than a satellite, which crosses the orbit of the planet nearest the stellar object or stellar binary.

I take biggest issue with this definition.

Halley's comet (Perihelion 0.59AU) would therefore not be a comet because it doesn't cross the orbit of Mercury (Aphelion 0.47AU)?

[sevenperforce]

9 minutes ago, RCgothic said:

I take biggest issue with this definition.

Halley's comet (Perihelion 0.59AU) would therefore not be a comet because it doesn't cross the orbit of Mercury (Aphelion 0.47AU)?

Oh, yep, you are absolutely right. For some reason I had it in my head that all comets had to have a perihelion closer than Mercury to experience coma cycles but that's definitely untrue, lol.

The shortest-period comets, like Encke, don't even cross Jupiter's orbit. And PANSTARRS doesn't cross the orbit of ANY planet. 

Maybe it's better to just designate comets as a subset of asteroids and say that a comet is an asteroid with an orbit eccentric enough to undergo periodic outgassing near perihelion? 

[RCgothic]

16 minutes ago, sevenperforce said:

Oh, yep, you are absolutely right. For some reason I had it in my head that all comets had to have a perihelion closer than Mercury to experience coma cycles but that's definitely untrue, lol.

The shortest-period comets, like Encke, don't even cross Jupiter's orbit. And PANSTARRS doesn't cross the orbit of ANY planet. 

Maybe it's better to just designate comets as a subset of asteroids and say that a comet is an asteroid with an orbit eccentric enough to undergo periodic outgassing near perihelion? 

Yes, that much better. I thought up that point after realising comet 2014 UN271 doesn't come inside the orbit of Saturn.

Also your original definition would define anything that even *slightly* crosses Mercury's orbit as a comet. Most things that close to the sun would be perpetually baked and barely outgas at all.

The key feature of comets is the outgassing I feel.

[kerbiloid]

We should put the comet in LPO. A shelter of miserables.

[Liz420]

 

I just watched a video that made me think... I say yes and no... Yes because people from 2005 and past learned that pluto was the smallest planet we had in our solar system. And the people from 2006 to present are not. Now to us gen Y and prior pluto will always be our wierdo planet. But lets pretend our solar system are highschool students instead of planets.. Pluto would be the little dorky kid that is picked on by everyone but also protected by everyone. Kinda like we can pick on him but no one else can. He's a wierdo but hes our wierdo. Now put yourself in Plutos position. Going from the dorky kid struggling to fit in. To becoming a slightly higher status in a smaller community. Pluto is finally fitting in.. Pluto has many friends now.. Pluto is happy. We older generation should not be upsett pluto is downsized to a dwarf planet we should be happy  because pluto is where he belongs. So i end this saying goodbye Pluto my dorky little 9th planet. Its time to fly away be your own little dwarf planet. 

[JoeSchmuckatelli]

I'm not sure Pluto has put much thought into it 

[Second Hand Rocket Science]

Quote

Maybe give it a billion years, and it will grow a bit?

@kerbiloid Unless something happened like the formation of our Earth where another planet just went "hey, I don't like you!" and hit Pluto, I don't think Pluto will grow any time soon. It's gravitational pull is tiny and it would have to be assisted somehow to become bigger. Probably. Don't ask me, ask a scientist!

Edited December 29, 2021 by Second Hand Rocket Science

[Admiral Fluffy]

Dwarf planets are planets too.

-Brad Wistsnce

[NFUN]

15 hours ago, Liz420 said:

But lets pretend our solar system are highschool students instead of planets

let's not

[kerbiloid]

In my schoolhood I was reading in books that Pluto is a planet several times more massive than Earth.

It has gotten degraded so much since then...

[Ben J. Kerman]

In my opinion, a dwarf planet is still a planet, just a dwarf one. I guess.

[kerbiloid]

Until the dwarves get too deep. Then it becomes Balrog's.

[sevenperforce]

On 12/30/2021 at 12:15 AM, kerbiloid said:

In my schoolhood I was reading in books that Pluto is a planet several times more massive than Earth.

It has gotten degraded so much since then...

Yes, we originally believed that there must be a super-earth outside the orbit of Neptune due to wobbles in the orbits of Neptune and Uranus. So we were looking for a super-earth out there when we found Pluto in 1930, and assumed it must be the super-earth causing Neptune and Uranus to wobble.

We didn't figure out we were wrong until 1976, when we calculated the albedo of Pluto and realized its surface was covered in super-reflective methane ice, meaning it had to be much smaller than it looked. But we soon realized that our initial estimates of Neptune's mass had been off; once the mass of Neptune was corrected, the wobbles finally matched the interactions expected between Uranus and Neptune, and so we realized there never had been a planet in the spot where we were looking.

Even if we did find a dwarf planet there by mistake.

[kerbiloid]

Then Pluto is a "mistaken planet".

[JoeSchmuckatelli]

11 hours ago, sevenperforce said:

We didn't figure out we were wrong until 1976, when we calculated the albedo of Pluto and realized its surface was covered in super-reflective methane ice, meaning it had to be much smaller than it looked. But we soon realized that our initial estimates of Neptune's mass had been off; once the mass of Neptune was corrected, the wobbles finally matched the interactions expected between Uranus and Neptune, and so we realized there never had been a planet in the spot where we were looking.

I never knew that part of the story - thanks for sharing!

 

(Starts gooling, ignoring the work that's much more boring)

[Minmus Taster]

Pluto is Pluto.

But what the heck yeah I say it is.

https://www.extremetech.com/extreme/330150-astronomers-make-the-case-for-calling-pluto-a-planet-again

[kerbiloid]

Pluton le Bâtard

 

A new class for the "less than planet, greaterthan asteroid" celestial bodies:  "b-ard planet".

Nobody wants to recognize them as his one.

Edited January 23, 2022 by kerbiloid

[NFUN]

On 1/22/2022 at 9:39 AM, Minmus Taster said:

Pluto is Pluto.

But what the heck yeah I say it is.

https://www.extremetech.com/extreme/330150-astronomers-make-the-case-for-calling-pluto-a-planet-again

That article is so terrible. "The IAU is using folk etymology to determine what counts as a planet, but Pluto looks like what people popularly imagine planets look like, so it should be a planet!"

[Minmus Taster]

52 minutes ago, NFUN said:

That article is so terrible. "The IAU is using folk etymology to determine what counts as a planet, but Pluto looks like what people popularly imagine planets look like, so it should be a planet!"

Agreed, but I wasn't adding it because it was good, but just because it was in the general feed for that topic.

[NFUN]

33 minutes ago, Minmus Taster said:

Agreed, but I wasn't adding it because it was good, but just because it was in the general feed for that topic.

was just commenting on the article

[Nuke]

i still consider ceres to be the fifth planet, this makes pluto planet x. 

according to the iau definition, if pluto isnt a planet, then neither is neptune. 

i never really cared, the only thing this debate has made clear is that our naming conventions really suck, whether you use the new system or the old one where pluto is a planet. 

we need something like this:

world - any round non-stellar object
planet - any world in a solar orbit
moon - any world in a planetary orbit
lump - things that would be called worlds if they were round
asteroid - a lump in a solar orbit
moonoid - a lump in a planetary orbit
sub-moon - a moon of a moon (probibly does not exist or for very long)
sub-moonoid - a lump orbiting a moon
astreroon - a lump orbiting an asteroid
tesloid - a tesla roadster orbiting the sun
tesloon - a tesla roadster orbiting a planet
teslet- a tesla roadster orbiting an asteroid
dontpanicite - a copy of hitchikers guide of the galaxy orbiting a tesla roadster. 
voidoid - anything orbiting a lagrange point
flyoid, anything orbiting the jwst. 

Edited January 26, 2022 by Nuke

[NFUN]

35 minutes ago, Nuke said:

according to the iau definition, if pluto isnt a planet, then neither is neptune.

 

no, that's false, you have definitely been told exactly how and why this is false before, people please stop saying this

[Nuke]

19 minutes ago, NFUN said:

no, that's false, you have definitely been told exactly how and why this is false before, people please stop saying this

im aware, my post was kind of a joke. 

did the iau ever pick an equation for determining what "clearing the neighborhood" means? last i read there were still a couple candidates.

Edited January 26, 2022 by Nuke

[kerbiloid]

There is the only planet in the Solar System, the Jupiter.

It contains 2/3 of the non-Solar mass, ~85% (from memory) of angular momentum, and it has cleared the neighborhood from random trash like the neptunes and earthes.

Saturn is a dwarf Jupiter, a Jupiteroid, or a Jupiterino.

[DunaManiac]

I personally think there should be a difference between planet and dwarf planet. If we make pluto a planet, then we'll have to add Eris too because they're the same size. Then we'll have to add Ceres, makemake, quaoar, etc. So I think that there should be a definition simply to keep things less cluttered. And I'm sorry but Pluto is a large mass of rock and ice several billion miles away that doesn't care what the people on the third one classify it as.

Spoiler

Also, how come everyone argues for Pluto, but no-one cares about Eris?