Pluto demoted

[Lord Zentei]

Pluto gets the boot

Pluto no longer a planet, say astronomers

Thursday, August 24, 2006; Posted: 9:32 a.m. EDT (13:32 GMT)

PRAGUE, Czech Republic (AP) -- Leading astronomers declared Thursday that Pluto is no longer a planet under historic new guidelines that downsize the solar system from nine planets to eight.

After a tumultuous week of clashing over the essence of the cosmos, the International Astronomical Union stripped Pluto of the planetary status it has held since its discovery in 1930.

The new definition of what is -- and isn't -- a planet fills a centuries-old black hole for scientists who have labored since Copernicus without one.

Pluto is no stranger to controversy. In fact, it's been dogged by disputes ever since its discovery. (Watch why some think planet size doesn't matter -- 3:39)

Discovered by Clyde Tombaugh of Arizona's Lowell Observatory, Pluto was classified as a planet because scientists initially believed it was the same size as Earth. It remained one because for years, it was the only known object in the Kuiper Belt, an enigmatic zone beyond Neptune that's teeming with comets and other planetary objects.

Pluto got an ego boost in 1978 when it was found to have a moon that was later named Charon. The Hubble turned up two more, which this past June were christened Nix and Hydra.

But in the 1990s, more powerful telescopes revealed numerous bodies similar to Pluto in the neighborhood. New observations also showed that Pluto's orbit was oblong, sending it soaring well above and beyond the main plane of the solar system where Earth and the other seven planets circle the sun.

That prompted some galactic grumbling from astronomers who began openly attacking Pluto's planethood.

At one point, things looked so bad for Pluto, the international union said publicly in 1999 that rumors of Pluto's imminent demise were greatly exaggerated and there were no plans to kick it out of the cosmic club.

A year later, the Hayden Planetarium at New York's American Museum of Natural History was accused of snubbing Pluto by excluding it from a solar system exhibition.

Pluto took another hit after Michael Brown of the California Institute of Technology discovered 2003 UB313, a slightly larger Kuiper Belt object. What's the point, some astronomers wondered, in keeping Pluto as a planet?

Its future brightened earlier this year, when NASA sent the New Horizons spacecraft to Pluto to get a closer look at the ball of rock and ice. The Hubble has managed to glimpse only its most prominent surface features; New Horizons, if all goes well, will arrive in 2015.

[VT-16]

So. Will Pluto, Ceres, Charon, "Xena" and all the other candidates become these new "dwarf planets" then? What was the criteria used for the final verdict?

[Zed Snardbody]

Who needs a death star when you have committees.

[GrandMasterTerwynn]

So. Will Pluto, Ceres, Charon, "Xena" and all the other candidates become these new "dwarf planets" then? What was the criteria used for the final verdict? :?

Nope. Here are the final guidelines. Quoted below:

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

* Planets: The eight worlds from Mercury to 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.

Under this definition, Pluto gets punted from "Planet" status to "Dwarf Planet" status, Charon goes back to being a satellite, Ceres, 'Xena' and the hundreds of round bodies in the Kuiper Belt and beyond get promoted to "Dwarf Planets" and it's business as usual for everything else.

[Lord Zentei]

So. Will Pluto, Ceres, Charon, "Xena" and all the other candidates become these new "dwarf planets" then? What was the criteria used for the final verdict?

Nope. Here are the final guidelines. Quoted below:

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

* Planets: The eight worlds from Mercury to 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.

Under this definition, Pluto gets punted from "Planet" status to "Dwarf Planet" status, Charon goes back to being a satellite, Ceres, 'Xena' and the hundreds of round bodies in the Kuiper Belt and beyond get promoted to "Dwarf Planets" and it's business as usual for everything else.

How "round" does it have to be? Did they lay down any guidelines on that?

[Rye]

Awesome, Pluto wasn't just tiny , it had a fucked up orbit totally out of line with the other planets and generally didn't compare to the other planets as much as it did to compacted KBO debris.

[VT-16]

Charon goes back to being a satellite

Why exactly? It and Pluto circle around a point inbetween them, it doesn't circle Pluto.

[Simplicius]

This is probably an ignorant question - the reason the definition is solar system-centric is because anything we can currently detect orbiting other stars is plainly large enough to be classified as a planet, right?

[The Guid]

Shouldn't it be renamed to Sneezy?

[RedImperator]

This is probably an ignorant question - the reason the definition is solar system-centric is because anything we can currently detect orbiting other stars is plainly large enough to be classified as a planet, right?

Yes. We might have to shitcan this whole scheme if we send a probe to Alpha Centauri and it discovers something totally different. But for now, it works. The extrasolar planets we've discovered are at least ten times the size of Earth. The only doubt about their status is if some of the biggest ones actually qualify as brown dwarf stars instead of planets.

[LadyTevar]

NO NO NO No NO NO NO!!!
Dammit, this is why you never have Declarations by Committee! you get Playapi instead of ducks!

This is just stupid, I can't believe they dropped Pluto. What about Tradition, History?

[Stark]

Bout bloody time too. Stupid Pluto. And Tev, it's called 'correcting our mistakes'. The tradition defence only works for the Roman Catholic Church.

[GrandMasterTerwynn]

NO NO NO No NO NO NO!!!
Dammit, this is why you never have Declarations by Committee! you get Playapi instead of ducks!

This is just stupid, I can't believe they dropped Pluto. What about Tradition, History?

Tradition, in this case, is entirely meaningless. When Pluto was first discovered, it was originally thought the world was Earth-sized and all by its lonesome, orbiting in a reasonably circular orbit. Then further observations forced a steady downward revision of Pluto's mass, until they realized that Pluto was much, much too small to account for the anomalies in the orbits of Uranus and Neptune. (In fact, it is no more than a spectacular coincidence that Clyde Tombaugh spotted Pluto where Percival Lowell and other astronomers had postulated that a planet would be. For that matter the so-called anomalies in the orbits of Uranus and Neptune were easily explained by the fact that the estimates of Neptune's mass at the time were on the low side.) They also realized that Pluto was in this freakish orbit. And in the late 1990s, we discovered that Pluto wasn't quite alone in its region of space. There were other bodies sharing Pluto's basic composition. In the 2000s, we discovered that an object of its size is not unusual for an object orbiting in the Kuiper Belt, rendering Pluto an entirely pedestrian KBO that happened to be in the right place at the right time.

And for that matter, it can be easily shown that there is traditional precedent for dealing with upstart would-be planets . . . The exact same thing happened to Ceres nearly two centuries ago. It was discovered where scientists of the time thought a planet should be. It was initially hailed to be a planet as well. It quickly turned out to be rather small for a planet, and then they discovered several other bodies of roughly similar size in the same region of space. So scientists and astronomers of the day demoted Ceres to one of what would turn out to be tens of thousands of asteroids. (Though Ceres, by itself, comprises a full third of the mass of the entire asteroid belt. It's a bit more important relative to the bodies sharing its territory than Pluto is relative to the rest of the Kuiper Belt. So it fully deserves its elevation from mere asteroid to dwarf planet. Just as Pluto's demotion has been a long time coming.)

[Vehrec]

The Death of Pluto Yes, the blood is coming from where you think it is. Yes, this is WHO you think it is.

[VT-16]

Well, shit, dwarf planet is still a planet. That's good enough for now. 8)

[Spookster]

I think another reason ceres was demoted was because of it's odd shape. And of course they are only planets when they are round. Lord knows Earth isn't a little egg-shapped itself. Either way, here is a pretty good paper written about 2003 UB313 and 2003 EL61. From Cal tech

[Alyeska]

From what I can tell the difference between dwarf planet and planet is arbitrary.

Pluto is still a planet.

Anyway it seems the committe decided to avoid taking the most logical proposal. Fucking stupid.

[CaptainChewbacca]

The difference between a dwarf planet and a planet isn't arbitrary, its a function of size and gravity and its ability to clear its own orbit of debris.

[DesertFly]

It's about time. Pluto didn't deserve it.

[Admiral Valdemar]

From what I can tell the difference between dwarf planet and planet is arbitrary.

Pluto is still a planet.

Anyway it seems the committe decided to avoid taking the most logical proposal. Fucking stupid.

With respect, this decision makes perfect sense. And I'm willing to bet the hundreds of experts - the ones with doctorates in astrophysics - that helped bring about this change know more than anyone on this board with regards to celestial classification.

[VT-16]

I just think this last "extra" criteria sounds like it was slapped on at the final moment. What exactly is "ability to clear its own orbit of debris"?

How distant must the debris be to the planet? How concentrated must the debris be to be counted?

[CmdrWilkens]

I just think this last "extra" criteria sounds like it was slapped on at the final moment. What exactly is "ability to clear its own orbit of debris"?

How distant must the debris be to the planet? How concentrated must the debris be to be counted?

I would guess that either:

A) It was left deliberately vauge so that unforseen circumstances in distant solar systems will not neccessarily upset the system.

or

B) The actual definition of clearing debris from its orbit has a great deal of additional technical specification which really is never going to be printed in a newspaper or news magazine article.

Remember we don't have the exact wording of the final system nor will we unless someone happens to subscribe to any of the technical journals which wil innevitably carry this information.

[Admiral Valdemar]

Well, some contest that final part, stating that Earth, Mars and Jupiter all have asteroids in their paths or around Trojan or other Lagrange points. Time will tell whether this will be further elucidated or amended.

[Ender]

so would earth be a dwarf planet now? Or would the fact that all those satellites and such were put there by us make them free from the "clearing its orbit" distinction?

[VT-16]

Also thought of another fun scenario after my last post:

What if we found a planet that might have had a moon be destroyed and now littering it? Would this planet not be a planet until it cleared its surroundings? Hey, to take examples from our system, what about Jupiter, Saturn, Uranus and Neptun? Doesn't their rings count as debris? They're not going to be cleared for a while. :P