Pluto's not a planet, or is it?

[Denny Crane]

It's not exactly news, but Pluto is no longer considered a planet.

The term "planet" comes from the greek (ancient) word for "wanderer." From when the greeks named them planets to present day, there never really was a definition of what a planet actually is.

So scientists took a vote and the word is now defined in such a way that Pluto doesn't qualify.

Pluto is ridiculously far away from the sun, and it's very small. If it crashed into the USA, it'd fit between california and kansas. It's very close to, or part of, the kuiper belt and many scientists argue that it is actually a kuiper belt object or basically a really big asteroid or comet. The kuiper belt is a very massive region of space populated with the leftover debris from the formation of the solar system...

Recently, an object larger than Pluto and further out has been found. It's discovery actually led to the scientists getting together to discuss the definition of a planet. The definition they came up with was ultimately that the celestial body had to clear or accrete all of the material in its orbit. This is true of the first 8 planets, but not for Pluto.

There is no consensus among scientists about what a planet is. It may be something that can't be well defined - like pornography, you know it when you see it. Or like if you see a great dane next to a chiuaua, you recognize them both as dogs.

One of the more common sense arguments that Pluto is a planet is that it's round, has 3 moons, orbits the sun (though not circular like the other 8), and if you flew the starship enterprise to it and went into orbit, you'd see what you'd call a planet on the big screen.

I've followed this controversy with interest for a few years now. I tend to think that Pluto is indeed a planet and that being round (unlike the potato shaped objects in the kuiper belt) and orbiting the sun in its own right (vs. orbiting another body that orbits the sun), that it has moons and an atmosphere, justifies it being called one.

The ramifications of Pluto being a planet are profound. It's a point in scientific history where the flat earthers will have to accept a new reality. What are considered the 8 planets now would become the oddballs, and the most common kind of planet would be these tiny round objects very very far from the sun.

It also brings into question any and all of the so-called planets that have been "discovered" around distant stars. For them to be classified as actual planets, we'd have to prove they have cleared the objects from their orbits, their orbits are circular, that they orbit the plane of the ecliptic, etc.

With progress comes inconvenient truths.

So be it.

 

[speeds]

You're just a contrarian, aren't you Denny?

 

[barfo]

The ramifications of Pluto being a planet are profound.

Profoundly semantic.

It's a point in scientific history where the flat earthers will have to accept a new reality.

No they won't. That's the whole point of being a flat earther, not having to accept new realities.

barfo

 

[jlprk]

Many objects have been discovered farther out than Pluto, but still orbiting the Sun. About 20 have a diameter of at least 400 miles (the minimum to coalesce from a potato shape into a sphere). I made a spreadsheet of them a few years ago, including approximate diameters. I'm looking at it now. The biggest are Quaoar (783 miles), 2003EL61 (1000), Orcus (994), Sedna (1000), Makemake (1118), Pluto (1413), and Eris (1491). Some have known moons. The rest probably have undiscovered moons.

Recently, an object larger than Pluto and further out has been found.

That was Eris in 2005. It was the first object found beyond Pluto that is also bigger than Pluto.

I tend to think that Pluto is indeed a planet and that being round (unlike the potato shaped objects in the kuiper belt) and orbiting the sun in its own right (vs. orbiting another body that orbits the sun), that it has moons and an atmosphere, justifies it being called one.

Many have pushed for that definition of planet, as anything spherical not orbiting a planet. That definition would include the 20 spheres beyond Pluto, plus the 9 usual planets. The 20 number will grow, but not the 9.

What are considered the 8 planets now would become the oddballs, and the most common kind of planet would be these tiny round objects very very far from the sun.

Many have written that, too. It follows logically if you use the definition of planet as anything spherical not orbiting a planet. The 20 out of 29 would be the majority, growing as more are discovered. We inner 9 planets would be in the minority.

 

[Eastoff]

Many have written that, too. It follows logically if you use the definition of planet as anything spherical not orbiting a planet. The 20 out of 29 would be the majority, growing as more are discovered. We inner 9 planets would be in the minority.

I got mine, so I don't want any of those other planets getting theirs! Keep the solar system pure!

 

[Denny Crane]

Many objects have been discovered farther out than Pluto, but still orbiting the Sun. About 20 have a diameter of at least 400 miles (the minimum to coalesce from a potato shape into a sphere). I made a spreadsheet of them a few years ago, including approximate diameters. I'm looking at it now. The biggest are Quaoar (783 miles), 2003EL61 (1000), Orcus (994), Sedna (1000), Makemake (1118), Pluto (1413), and Eris (1491). Some have known moons. The rest probably have undiscovered moons.



That was Eris in 2005. It was the first object found beyond Pluto that is also bigger than Pluto.



Many have pushed for that definition of planet, as anything spherical not orbiting a planet. That definition would include the 20 spheres beyond Pluto, plus the 9 usual planets. The 20 number will grow, but not the 9.



Many have written that, too. It follows logically if you use the definition of planet as anything spherical not orbiting a planet. The 20 out of 29 would be the majority, growing as more are discovered. We inner 9 planets would be in the minority.

I agree with all of this. Eris is the goddess of strife and discord, an appropriate name for this newly found planet.

Pluto has been defined as a planet since it was found until recently. Nothing changed about Pluto but the definition of what a planet supposedly is.

Pluto was discovered by Clyde Tombaugh in 1930. He took photographs of the same point in space at different times and visually compared the two images. The stars remained in the same position and something that looked like a star that moved from one image to the other was pluto. It was painstaking physical work that paid off and opened up a huge part of the solar system to discovery.

These days, we have high resolution digital cameras that can take the two images of the same space and computers can compare the digital images. Hence we found Quaoar, Eris, et al. We'll surely find many more.

Speeds, this isn't about being a contrarian, it just flies in the face of common sense to define a planet as the scientists voted. For one, voting isn't a scientific process (we've been through that). For another, there are simply obvious things like the distance from the sun, temperature, time to orbit the sun, the gravitation of heavier materials toward the sun (or cores of the inner planets) that explain why a pluto wouldn't accrete all the material within its orbit.

Like, it takes pluto 250 earth years to orbit the sun so it makes sense it would be 1/250th the size of earth. It's actually bigger than 1/250th.

The kuiper belt is an enormous sphere of debris around the sun. Much of the material is not on the plane of the ecliptic like the inner planets are. In spite of there being billions and billions of pieces of debris out there, each bit of it is extremely far from the next. It's not hard to fathom why Pluto couldn't accrete all the material out there within its orbit.

 

[Entity]

The word planet kind of got grandfathered into the current system. They could call the consensus eight a new word and Pluto something else, but we're still going to call them planets. The thing is, though, Pluto is an oddball in many different ways. Its orbit is so far off the plane the rest of the planets are on it looks like it was thrown into it's orbit:

Hell, Ceres is inside the eight planets, orbiting on the same plane as they are, and it's pretty sizable, but almost nobody cares about it's status. It's only "flaw" is the same thing keeping it out of planetary-status with Pluto. If Pluto's a planet, then this planetary system has a lot of planets. Classifying is all about putting things in rows and columns anyway. It's not going to prevent it from being any less useful than it might potentially be to us.

It's like, do I live in a city or a town? A metropolis? Different places have different definitions of those things, but there's really no consensus except in what order they appear from largest to smallest. It's all about prestige, and Pluto has no residents to defend its name. Just enthusiasts.

 

[Eastoff]

The word planet kind of got grandfathered into the current system. They could call the consensus eight a new word and Pluto something else, but we're still going to call them planets.

They adopted the term "planetoid" I thought to describe pluto and others in the keiper belt.

 

[Eastoff]

For one, voting isn't a scientific process (we've been through that).

Well they are voting on definitions, which isn't that much about science as it is about common terminology for science.

Like, it takes pluto 250 earth years to orbit the sun so it makes sense it would be 1/250th the size of earth. It's actually bigger than 1/250th.

Maybe I'm forgetting something, but the orbit around the sun shouldn't be exactly dependent on mass as it should velocity. Are the rest of the planets' frequency of a full revolution extremely mass dependent?

 

[Minstrel]

For another, there are simply obvious things like the distance from the sun, temperature, time to orbit the sun, the gravitation of heavier materials toward the sun (or cores of the inner planets) that explain why a pluto wouldn't accrete all the material within its orbit.

Yes, and for those reasons, it's not a "planet."

This is kind of a strange tone you're striking. It's almost like you view this as a value judgment...like Pluto is being "blamed" for not clearing out its orbit and thus is being "penalized." There's nothing inherently good or bad about being a planet...scientists decided to standardize what objects should be termed a planet and decided on one reasonable choice. There are other reasonable choices, but one has to be used if you want a standard term.

Why does it matter if Pluto is a "planet" or a "planetoid?" It's not a knock on Pluto and Pluto doesn't really care either way.

 

[PtldPlatypus]

Yes, and for those reasons, it's not a "planet."

This is kind of a strange tone you're striking. It's almost like you view this as a value judgment...like Pluto is being "blamed" for not clearing out its orbit and thus is being "penalized." There's nothing inherently good or bad about being a planet...scientists decided to standardize what objects should be termed a planet and decided on one reasonable choice. There are other reasonable choices, but one has to be used if you want a standard term.

Why does it matter if Pluto is a "planet" or a "planetoid?" It's not a knock on Pluto and Pluto doesn't really care either way.

How do you know whether or not Pluto cares? Have you ever spoken with Pluto? Isn't it possible that Pluto's self-esteem is more fragile than you realize?

You know, Pluto performed just fine when it had a nice, defined role as the ninth (and occasionally eighth) planet. It knew what was expected, and it met those expectations admirably. But now, you and your ilk decide that we need to cut down to an 8-planet rotation, and suddenly Pluto is on the outs.

Is Pluto less valuable now than it was five years ago? Have Pluto's contributions to the solar system been deemed no longer necessary? What's next, are you going to try to trade Pluto to another star for a pair of asteroids and a comet to be named later? Where's the loyalty? Where's the honor?

You make me sick.

 

[jlprk]

it just flies in the face of common sense to define a planet as the scientists voted.

Changing the definition does make sense because--
The options were to use the old definition and have about 29 planets, with the number growing and growing over future decades, or to keep the number manageable by having a new definition. They expect to discover at least another 29, in fact--Many astronomers say there are hundreds way out there that are over the minimum spherical diameter of about 400 miles. (Hundreds of smaller ones have already been discovered.) They figured a new term can be invented for the small ones, like planetoid, and wanted to save the term planet for something meaningful to most people. If they hadn't changed the definition of planet, they would have had to invent a new word for the inner 8 or 9. Then you would have heard the new word in place of whenever you currently hear "planet" and you'd hardly ever hear "planet." It meant less change to the language to do it the way they did. New discoveries forced it.

The part about sweeping out other objects in the same orbit simply means that it's not a planet if there are other objects about the same size there (which eliminates the spherical Ceres in the asteroid belt). So the new definition requires the planet to have enough gravity to merge with other objects in its orbit, but not necessarily enough gravity to shape into a sphere.

 

[Denny Crane]

Changing the definition does make sense because--
The options were to use the old definition and have about 29 planets, with the number growing and growing over future decades, or to keep the number manageable by having a new definition. They expect to discover at least another 29, in fact--Many astronomers say there are hundreds way out there that are over the minimum spherical diameter of about 400 miles. (Hundreds of smaller ones have already been discovered.) They figured a new term can be invented for the small ones, like planetoid, and wanted to save the term planet for something meaningful to most people. If they hadn't changed the definition of planet, they would have had to invent a new word for the inner 8 or 9. Then you would have heard the new word in place of whenever you currently hear "planet" and you'd hardly ever hear "planet." It meant less change to the language to do it the way they did. New discoveries forced it.

The part about sweeping out other objects in the same orbit simply means that it's not a planet if there are other objects about the same size there (which eliminates the spherical Ceres in the asteroid belt). So the new definition requires the planet to have enough gravity to merge with other objects in its orbit, but not necessarily enough gravity to shape into a sphere.

This isn't for your benefit: they're using the term "Dwarf Planet" for objects like Pluto, not "planetoids" - at least as I've seen and read about it.

I'm at a loss as to why there being 29 planets is a big deal.

Heck, Jupiter has 63 moons (that we've discovered). Maybe we should change the definition of moon so there are fewer?

Saturn, Jupiter, and Neptune have rings, so they haven't cleared all the objects from their orbit. They must not be planets. Earth didn't clear the moon from its orbit...

On the other hand, if it's merging with one other object, I don't see how anyone can prove (at this time) one way or the other if Pluto has merged with at least one other.

Though especially so far from the sun, being round is a pretty good indication that it has merged with a number of other objects. Or subject to great tidal forces (if it were ejected from the inner solar system, say). Or composed of a lot of radioactive material. Those are guesses, of course, since we can't see it in detail (see this deep space hubble photo of it here: http://zuserver2.star.ucl.ac.uk/~idh/apod/ap051103.html).

 

[Denny Crane]

FYI:

http://www.plutotoday.com/news/viewpr.html?pid=20725

 

[barfo]

It's amazing that people can come up with ways to spend time even less productively than posting on basketball message boards.

I say toe-may-toe (roughly spherical, no moons).

barfo

 

[jlprk]

I go light on everyone on the board. No need to show people up. But I'm talking to the big guy now. You hear me, Boss Man? You're not big, just tall.

Listen up, Crane. You wouldn't know the difference between a planet and a moon if it slapped you in the face. A real wiseguy. I'll just highlight where you went wrong, no need to write a book to make the whole list.

This isn't for your benefit:

First of all, from now on everything on this board will be for my benefit. That's right, I'm muscling in. I want 10% off the top, not after you take out your piece. Have both sets of books ready for me to eye when I come around to collect. Just a peek will do. They better be all finished for the month, with all your Ps and Qs in the dollar and cents column. My nephew Alphonse wants to work for you. He likes you. So I'll bring him to meet you. He wants to learn the financial side of the business.

Saturn, Jupiter, and Neptune have rings, so they haven't cleared all the objects from their orbit. They must not be planets. Earth didn't clear the moon from its orbit.

When you see old Shady Luigi loitering on the corner, is that the same as when my man Giovanni drives me around the neighborhood to make sure all is copacetti? Show some respect. The new definition requires the planet to sweep its orbit around the Sun so it has no rivals on the lam, not to clear all the little soldiers orbiting around the planet itself. Even big black holes can't pinch all the garbage unions circling them, not even the sewer holes in Newark, so how could a planet? Wise up.

I don't see how anyone can prove (at this time) one way or the other if Pluto has merged with at least one other.

Don't have to. Just prove that there's nothing there now to merge with, like there is in the asteroid belt. If the street has a code of silence, then the planet has swept its orbit clean. Why don't you sweep this floor so I can make some money here. My customers are complaining about you. You think you own this deli now? Are you lying with the fishes or do I smell a rat?

Though especially so far from the sun, being round is a pretty good indication that it has merged with a number of other objects. Or subject to great tidal forces (if it were ejected from the inner solar system, say). Or composed of a lot of radioactive material. Those are guesses, of course,

You're just stalling. You know the combination. Crack the safe and pull out the hot potato or I'll merge you and this piece of hot lead. When two things crash they look like a potato with lots of red sauce. There's no shake down into a ball unless heat and friction come from the gravity of the situation, you know what I mean?

 

[Denny Crane]

You're just stalling. You know the combination. Crack the safe and pull out the hot potato or I'll merge you and this piece of hot lead. When two things crash they look like a potato with lots of red sauce. There's no shake down into a ball unless heat and friction come from the gravity of the situation, you know what I mean?

The things I mentioned, collisions (friction), tidal forces, and radioactive elements are all sources of heat.

Seems like we're in agreement on this point.

The definition requiring an object to sweep all of the material in its orbit seems arbitrary to me. If we're looking for something to differentiate a planet from asteroids and comets, being round (may also be arbitrary) is what planets have in common.

 

[maxiep]

The science is settled.

 

[Minstrel]

How do you know whether or not Pluto cares? Have you ever spoken with Pluto? Isn't it possible that Pluto's self-esteem is more fragile than you realize?

You know, Pluto performed just fine when it had a nice, defined role as the ninth (and occasionally eighth) planet. It knew what was expected, and it met those expectations admirably. But now, you and your ilk decide that we need to cut down to an 8-planet rotation, and suddenly Pluto is on the outs.

Is Pluto less valuable now than it was five years ago? Have Pluto's contributions to the solar system been deemed no longer necessary? What's next, are you going to try to trade Pluto to another star for a pair of asteroids and a comet to be named later? Where's the loyalty? Where's the honor?

You make me sick.

Pluto has a well-known reputation as the most apathetic of the planet-like objects.

This is demonstrated by the fact that it didn't even care enough to clear out its own orbit. It plays by its own rules, and you think it cares what people call it?

That's just not how Pluto rolls. Or orbits.

 

[andalusian]

I think that the most important part of this thread is the fact that

1. Pluto has it's own newspaper (Pluto Today)
2. Pluto Today is available on the web

and

3. I can't find the sport section there

I blame Comcast.