DescentBB

Well, it looks like we only have 8 planets now.
Linky

So Pluto is 'dead', eh?


What will Mickey Mouse do now?

It's amazing they removed it's \"planet\" status.

This decision actually makes good scientific sense. Pluto really never was nothing more than a very large example of a Kuiper belt object. Of course, at the time of its discovery, the Kuiper belt wasn't really known, so it was given the designation of \"planet\" instead. (Even that wasn't without controversy, though.) In terms of the model of solar system formation, which explains why the inner planets are small and rocky and the outer are large gas giants, Pluto never really fit in. At least this definition makes a hell of a lot more sense than the whole \"12 planets now, possibly thousands in the future\" idea that was tossed around at the conference a week or so ago.

And it's certainly not \"goodbye\" to Pluto; it's not like it's going anywhere. It's actually taken on an important new role, as the prototype of a whole new classification known as \"dwarf planets.\" This decision certainly doesn't affect the status of the New Horizons mission, which should hopefully get us our first close-up pictures of Pluto and Charon around 2015 or so.

(All of that being said, the sentimental side of me does feel a little bit sad for it...)

I hope they don't try to take away the last few levels of Descent 1...

Top Gun wrote:In terms of the model of solar system formation, which explains why the inner planets are small and rocky and the outer are large gas giants, Pluto never really fit in.

Sorry, Not so!

The "model" you describe doesn't exist. Currently there is no known model which adequately explains creation of the small-rocky-inner / asteroid belt / gas-giant-outer solar system we inhabit. In order to arrive at out present system, all existing models need to be massaged artifically.

It was hoped that discovering extra-solar planets would show similar systems to our own, but so date, not a single "normal" solar system has been discovered. In fact the exact reverse is true: we now know that most solar systems with gas giants (The only size of planet we can detect at the moment) look very odd indeed: the gas giants are in close proximity to the sun, and some have orbital periods of only days, instead of years.

What we *DO* know from computer models is that solar systems which have Gas Giants of 11 or more Jupiter-masses are unlikely to have any other planets in them, as the gravity of the situation tends to toss small planets out of the solar system - or at least into wayward and eccentric KBO-type orbits.

The decision to remove Pluto as a planet is dumb: Pluto has always been a planet, and it should remain so! Kids spent hours learning about the planets, and to leave Pluto off this list is to almost miss the point about learning about the solar system: there are funny planets out there, and pluto is one of them!

I'd be more inclined to divide planets into three categories: Majors, Minors and oddities. Majors are anything Earth-size or larger, Minors are smaller than Earth and "Odd" planets are ones which don't entirely fit the mold, like Pluto and Charon - which should also be a planet in my view.

Yes, "Earth Size" is arbitrary - but so is the "AU" entirely arbitrary, so I can't see why it'd be a problem.

It's good that Pluto is no longer a planet, because Holst didn't write a movement for Pluto. For the same reason, Earth should be demoted.

This is a tough call for me. I'm sentimental so I wish Pluto to remain a planet but because of its characteristics that apply to others like it, it would open the door to many objects being reclassified as planets. Some say as much as 22.

Pluto and Charon act almost like a binary pair instead of planet and orbiting moon. In a binary pair, the rules are that the center of gravity must reside in one of them and the one that has it is the Planet and the other would be its moon. This applys to Jupiter, Saturn, etc, etc.

So, between our Earth and moon, the center of gravity is in Earth which makes it a planet with an orbiting moon. However, with Pluto and Charon, the center of gravity is between them.... that makes neither a true planet.

Anyway, I'll be buying my \"Save Pluto\" shirt soon.

Bee

Your idea seems pretty simialr to theirs Mobius, see:

The resolution
The decision establishes three main categories of objects in our solar system.

* Planets: The eight worlds starting with Mercury and moving out to Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
* Dwarf planets: Pluto and any other round object that \"has not cleared the neighborhood around its orbit, and is not a satellite.\"
* Small solar system bodies: All other objects orbiting the sun.

this seems to mean that 2003 UB313 (what the newspapers were calling PLANET X a few years back) will not be called a planet either. There was a bit of a kerfuffel when they discovered it because it was bigger than Pluto yet they didn't want to call it a planet. I guess this solves that problem.

I wonder how this will effect astrological (ie: spiritual) circles

Pluto was considered for astrology? Well, shouldn't matter, 'cause it's still a planet in a sense. Not like it matters anyway, it IS astrology, after all.

ya. Well as the planets get further out they seem to have more and more abstact meanings, as they were all discovered later and later they were kinda 'tacked-on' to astrology.

Astrology even tracks meteors and comets etc too, so i think the astoNOMICAL designation of whether these things are planets or not means little to Astrology - they are \"sky things\" .

I've got it! Someone should just go out there, grab some matter from Neptune or whatever, and add it onto Pluto until it's big enough to be a planet again. Problem solved.

Or, at least, this idea could be made into a movie. It would basically be a remake of The Englishman Who Went Up A Hill, etc., only sci-fi. With, you know, charmingly eccentric aliens and stuff.

I'm glad about the whole thing. I kinda like Pluto, but I like consistent definitions a lot more. It's Progress. To heck with tradition.

I'm also sorry, Mobius, but no. While the existence of Jovian-like planets at very close proximity to nearby stars remains somewhat of a mystery, astronomers have a pretty good picture of exactly how our solar system came to be, one that explains the inner planets, the asteroid belt, the outer planets, and Kuiper objects. Instead of summing things up, I'll just direct everyone to the Wiki article on the subject, which is a relatively easy read. (The more general article on our solar system is also useful.) There are a few complications in the model when compared with the actual solar system, but when you're talking about events that happened 4.6 billion years ago, that's something you'd expect. Just like any other field of science, the more data we gather, the more accurate model we are able to construct. (In fact, recent research has helped to piece together a more accurate model of how Uranus and Neptune came to be in their current orbits.) While there are competing models out there (there's one reference in the Wiki article to something called the Capture Theory, which I was only able to find a passing reference to via a Google search), the nebular model is what's backed up by our current data. Saying that we don't have any idea how our own solar system formed is flat-out wrong.

As for you saying that \"Pluto should be a planet because it has always been one,\" not only is it faulty reasoning, but it's also flat-out incorrect. Pluto was only discovered in 1930 and was labeled a planet at that time; now that we have a much clearer picture of the structure of our solar system, it's become apparent that Pluto is actually a very large example of a vast number of bodies known as Kuiper Belt objects. For another comparison, the large, round asteroid Ceres, which is considered a \"dwarf planet\" under the new system, was considered a planet throughout much of the 1800s; as we learned more about the solar system, however, we realized that it was a member of the asteroid belt, and its planetary status was removed. I'm as sentimental about Pluto as the next person, but sentimentality can't be used as a determining factor for the scientific method, now can it? As I said above, science is a dynamic field; as new data comes in, old definitions/theories may have to be tweaked, or entirely new definitions/theories might have to be created. What this whole debate showed was the scientific method in action. Honestly, you think someone like you would be able to understand this.

P.S. And what's so arbitrary about the astronomical unit? It's based on a concrete distance, that between the Earth and the Sun. Considering that we live on Earth, which just so happens to be in a solar system, using our own distance from the Sun as a benchmark to measure other intra-system distances against makes perfect sense. It's the same exact principle as the use of a light-year to measure interstellar/intergalactic distances.

Pluto has no atmosphere does it?

How can you be sentimental about a ball of rock/ice that you've (probably) never seen?

I'm glad they aren't going to stick with 'plutons' That was dumb. They're dwarves. I'm more excited that we have a double planet in our mostly boring solar system.

(Pluto is too small for an atmosphere, unless you can call a hazy fog on the surface an atmosphere)

Pluto was never as popular as Goofy, It's probably good they dropped him.

Does it matter?

We'll never get there. And I'd rather not if we could. It's cold up there.

Whatever. Hey, in a billion years or so, it'll be academic anyway.

Beowulf wrote:We'll never get there. And I'd rather not if we could. It's cold up there.

Why would that matter? Pluto is still there, it wasn't physically changed. The only difference is that we don't refer to it as a major planet anymore.

ya it's all just semantics, the universe doesn't care about our language and catagorys. Pluto hasn't changed

Bet51987 wrote:Pluto and Charon act almost like a binary pair instead of planet and orbiting moon. In a binary pair, the rules are that the center of gravity must reside in one of them and the one that has it is the Planet and the other would be its moon. This applys to Jupiter, Saturn, etc, etc.

Actually, in the new system, I believe they're calling Pluto a dwarf planet and they're still calling Charon its moon.

There was a proposal that Charon be promoted to a planet along with Ceres and Xena. Instead Pluto was demoted to dwarf planet, Ceres and Xena were promoted to dwarf planet, and Charon remains Pluto's moon.

But it's not really a moon. The gravitational point between the two objects lies outside both bodies. That is a double dwarf.

You'd think it should be. =)

At least Ceres got promoted.

Suncho wrote:

Bet51987 wrote:Pluto and Charon act almost like a binary pair instead of planet and orbiting moon. In a binary pair, the rules are that the center of gravity must reside in one of them and the one that has it is the Planet and the other would be its moon. This applys to Jupiter, Saturn, etc, etc.

Actually, in the new system, I believe they're calling Pluto a dwarf planet and they're still calling Charon its moon.

There was a proposal that Charon be promoted to a planet along with Ceres and Xena. Instead Pluto was demoted to dwarf planet, Ceres and Xena were promoted to dwarf planet, and Charon remains Pluto's moon.

Because of the latest rulings Charon (sounds like Karon) is no longer a moon but is now on equal footing with Pluto. A dwarf planet. Nix and Hydra are still moons of Pluto however.

Either way, if anyone is sentimental like me, just remember that Pluto is now the founder of dwarf planets. In dwarf books Pluto will be on every cover. A cool tribute to the king of dwarfs.

Bettina

Bettina, where can you find evidence that Charon has been promoted to a dwarf planet? All I can find is stuff like this:

Dwarf planets: Pluto and any other round object that \"has not cleared the neighborhood around its orbit, and is not a satellite.\"

Since Charon is classified as a satellite of Pluto, that makes it *NOT* a dwarf planet.

Suncho wrote:Since Charon is classified as a satellite of Pluto, that makes it *NOT* a dwarf planet.

To be classified as a satellite, the point of rotation between Pluto and Charon would have to be within Pluto. It's not. ergo, they are a binary dwarf planet pair instead of a dwarf planet and satellite.

Kilarin wrote:

Suncho wrote:Since Charon is classified as a satellite of Pluto, that makes it *NOT* a dwarf planet.

To be classified as a satellite, the point of rotation between Pluto and Charon would have to be within Pluto. It's not. ergo, they are a binary dwarf planet pair instead of a dwarf planet and satellite.

Suncho is right. My mistake. Pluto is now classified as a Dwarf Planet but Charon remains its moon. I have a "New Scientist" membership but read the article too fast... Sorry.

From the article....

"A few tricky issues in the first draft definition have been avoided. One contentious point was that Pluto and its companion Charon would have become a double planet. But that idea has been dropped. Charon remains a moon."

Bee

Bettina wrote:Charon remains a moon.

Really? Interesting. I stand corrected.

bah! why didn't they clasify charon/pluto as a doubledwarf? conservative pandering o rly

all the hype about pluto and nothing about our very own mooooooon? for shame!

http://www.cnn.com/2006/TECH/space/08/1 ... index.html

our moon will never diverge enough to be called a planet. Vapourisation due to huuuuuge-expanding-sun is scheduled before that.

roid wrote:our moon will never diverge enough to be called a planet. Vapourisation due to huuuuuge-expanding-sun is scheduled before that.

Really? Where's your evidence?

The Barycenter is 1060 miles from the surface of Earth, and the moon moves bout an inch a year from the planet, so..

67,161,600 years.

That's assuming the barycenter moves with the moon, which is doesn't. It would probably only move millimeters a year. That jumps that number to over 6 billion years, which is roughly longer than our sun has left before it changes to a red giant.

Where's your evidence?

in my pants.

But where are THEY? where indeed

roid wrote:

Where's your evidence?

in my pants.

If you can fit both the sun and the earth into your pants, then you must be very fat indeed.

TIGERassault wrote:

roid wrote:

Where's your evidence?

in my pants.

If you can fit both the sun and the earth into your pants, then you must be very fat indeed.

Naw... just "big boned".

Top Gun wrote:There are a few complications in the model when compared with the actual solar system

Actually there are more than a few complications.

The unexpected numbers of 'hot jupiters' found orbiting close to host stars is not easily dismissed; it is throwing some major wrenches in the whole theory of accretion.

If you read the details on this it only gets more puzzling.

Origins of the asteroid belt - this is another major point of contention. Origins of comets (Oort cloud is far from proven). Origins of major and minor moons of Jupiter and Saturn. The list goes on ..

I think science has become more concerned with keeping the status quo and scientists more concerned with holding onto research grants .. rather than genuinely gathering evaluating data and coming up with predictive theories

This is one of the main problems today and this is why we have whole fields of study (like planetary science and astrophysics) that are constantly shocked by a reality that doesnt fit the "models"

Not exactly OT for this thread, but it does figure in when devising classification schemes for solar objects we (honestly) are not positive of where they all came from, how many there are and what makes them fundamentally different from each other in the first place.

.

Testiculese wrote:The Barycenter is 1060 miles from the surface of Earth, and the moon moves bout an inch a year from the planet, so..

67,161,600 years.

That's assuming the barycenter moves with the moon, which is doesn't. It would probably only move millimeters a year. That jumps that number to over 6 billion years, which is roughly longer than our sun has left before it changes to a red giant.

Again, you need to show some evidence, you've provide quite a range in your answer.

It's not that I don't believe you, it's that I've heard from several TV space programs that the Earth would one day lose the moon. I would find it interesting that the people who determined that forgot to account for the sun expanding in 4.5 billion years or so.