Challenge Thread: Were you wrong about Pluto?

[AV1611VET]

I guess that means Jupiter is a quintuple planet system then, since Jupiter and it's four largest moons would be classified as planets by that reasoning. @AV1611VET does that sound good to you?

 

[Yttrium]

I guess that means Jupiter is a quintuple planet system then, since Jupiter and it's four largest moons would be classified as planets by that reasoning. @AV1611VET does that sound good to you?

I was only swapping out the new rule. The previous rules would still apply. So no moons.

(Not that I personally have anything against calling the larger moons planets, mind you. I mean, Ganymede and Titan are bigger than Mercury!)

 

[Hans Blaster]

I was only swapping out the new rule. The previous rules would still apply. So no moons.

(Not that I personally have anything against calling the larger moons planets, mind you. I mean, Ganymede and Titan are bigger than Mercury!)

What about moon-sized space stations?

 

[Yttrium]

What about moon-sized space stations?

Are they in hydrostatic equilibrium? If so, then sure, why not.

 

[chad kincham]

In another thread, someone made this comment:
If this is your sentiment as well, were you wrong about Pluto being our ninth planet?

I always preferred Goofy over Pluto in Disney cartoons...

 

[Kylie]

Well, if that doesn't suit you, how about you actually answer the questions I asked you in post 296?

1. How many things in our solar system do you think SHOULD be counted as planets?
2. Please give me a definition of "planet" we can use.

 

[Kylie]

I was only swapping out the new rule. The previous rules would still apply. So no moons.

(Not that I personally have anything against calling the larger moons planets, mind you. I mean, Ganymede and Titan are bigger than Mercury!)

How do you define "moon"?

As "something that orbits another object"?

 

[Yttrium]

How do you define "moon"?

As "something that orbits another object"?

A natural satellite. No reason something can't be a moon and a planet at the same time, if we allow certain natural satellites to be planets. The terms don't have to be mutually exclusive.

 

[Kylie]

A natural satellite. No reason something can't be a moon and a planet at the same time, if we allow certain natural satellites to be planets. The terms don't have to be mutually exclusive.

Well, how do you define "satellite"?

 

[Yttrium]

Well, how do you define "satellite"?

Why are you asking me to define everything? Have I made an astronomical faux pas somewhere along the line?

 

[Kylie]

Why are you asking me to define everything? Have I made an astronomical faux pas somewhere along the line?

No, sorry if it comes across that way.

I'm just saying that since Jupiter and the sun orbit their barycenter, one could argue that the sun is a moon of Jupiter.

I personally wouldn't, but there could be the argument put forth, and it would not be entirely without merit.

 

[Yttrium]

I'm just saying that since Jupiter and the sun orbit their barycenter, one could argue that the sun is a moon of Jupiter.

I personally wouldn't, but there could be the argument put forth, and it would not be entirely without merit.

Um... I can't really see how one could make that argument. Technically, both objects orbit the barycenter. But we consider the object of lesser mass to be the moon of the object with the greater mass.

 

[Opdrey]

I always preferred Goofy over Pluto in Disney cartoons...

There's a whole mess of "classifications". Goofy nominally appears to be a "dog" like Pluto but clearly Pluto is actually a "dog" while Goofy is another "anthropomorphized talking being" on a level with Mickey and Mini.

And when you add in the unnatural relations with his girlfriend who was a cow it only gets more confusing.

Clearly Neil DeGrasse Tyson needs to be called in to settle this ASAP.

 

[Kylie]

Um... I can't really see how one could make that argument. Technically, both objects orbit the barycenter. But we consider the object of lesser mass to be the moon of the object with the greater mass.

If we say that two objects, A and B, orbit the center of mass which is between them, any reasoning that says that B orbits A can be used to reason that A also orbits B.

Yes, you can say that if one object has more mass than the other, then the more massive object is considered the planet and the least massive object is the moon, but where do you draw the boundary? If A has a mass of 1 Earth Mass and B has a mass of 1.001 Earth masses, we'd still just say it's a double planet system, wouldn't we?

And what about binary stars? Very often there is a fairly significant difference in mass there. Can a star also be a moon?

 

[Yttrium]

Yes, you can say that if one object has more mass than the other, then the more massive object is considered the planet and the least massive object is the moon, but where do you draw the boundary? If A has a mass of 1 Earth Mass and B has a mass of 1.001 Earth masses, we'd still just say it's a double planet system, wouldn't we?

Ha ha, not according to the IAU. Under the current IAU definition, they wouldn't be planets, because they haven't cleared their orbit of each other. This is yet another reason that the clearing orbit bit is bogus. You could have binary objects the size of Jupiter and they wouldn't count as planets. But there is no such pair in our solar system, so the IAU doesn't care.

Yeah, the slightly less massive one would be the moon of the slightly more massive one.

And what about binary stars? Very often there is a fairly significant difference in mass there. Can a star also be a moon?

Y'know, I don't see why not. But good luck finding somebody who calls Alpha Centauri B a moon.

 

[Kylie]

Yeah, the slightly less massive one would be the moon of the slightly more massive one.

I don't think ANYONE would say the 1 Earth Mass object is the moon of the 1.001 Earth Mass object. We'd say it's a dual planet thing.

Y'know, I don't see why not. But good luck finding somebody who calls Alpha Centauri B a moon.

My point exactly!

 

[FrumiousBandersnatch]

If we say that two objects, A and B, orbit the center of mass which is between them, any reasoning that says that B orbits A can be used to reason that A also orbits B.

Yes, you can say that if one object has more mass than the other, then the more massive object is considered the planet and the least massive object is the moon, but where do you draw the boundary? If A has a mass of 1 Earth Mass and B has a mass of 1.001 Earth masses, we'd still just say it's a double planet system, wouldn't we?

And what about binary stars? Very often there is a fairly significant difference in mass there. Can a star also be a moon?

I thought one of two mutually orbiting bodies is considered to be a satellite of the other when the barycentre is within the circumference of the other. But I may have misunderstood - it doesn't work for Jupiter and the sun...

 

[Yttrium]

I thought one of two mutually orbiting bodies is considered to be a satellite of the other when the barycentre is within the circumference of the other. But I may have misunderstood - it doesn't work for Jupiter and the sun...

It also doesn't work for Pluto and its moon Charon.

 

[essentialsaltes]

 

[RDKirk]

What are the stakes of the debate such that laypeople should be so concerned about a change in taxonomy?