Starship Asterisk*

From what I've been reading on the BBC website and various sources, it seems that the IAU has made a rather large foul-up in their definition of a planet. If this is actually the wording of their declaration

(from the washington post
http://www.washingtonpost.com/wp-dyn/co ... 00109.html)

A celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a . . . nearly round shape, and has cleared the neighborhood around its orbit.

The article and the BBC one state :

It's the last part of the definition that doomed Pluto. Its oblong orbit overlaps with Neptune's.

Does anyone else see the major problem with this definition? If this is what was passed at the IAU they have also managed to downgrade Neptune and Jupiter, because if Pluto is not an planet for that reason then neither is Neptune (it hasnt cleared Pluto from its orbit), and Jupiter has not cleared its orbit, the Trojan asteroids share Jupiters orbit, but are located far enough in front and behind Jupiter that it can never clear them. It would have been simpler to just add a size or mass limit.

It may be just faulty reporting but I cant check on the IAU website a the minute because of all the traffic.

I guess this means that planetary status stops at Uranus and that big ball of gas after Uranus is just a fart.

Since Pluto;Charon; Ceres;etc. are now dwarf planets than maybe Jupiter; Saturn; Uranus;and Neptune should be reclassified as jumbo planets; leaving only four planets. Mercury; Venus; Earth; and Mars.
Orin

What about the stipulation that the planetary body needs to be able to maintain an atmosphere? Mercury has none and can't maintain an atmosphere due to it's close proximity to the Solar influence and Mars is slowly loosing its atmosphere to space so It's atmosphere isn't being "Maintained" either. They could be reclassified as large minor planets leaving just 2 actual planets that meet "All" criteria. Saturn could also be removed from the planetary list as the majority of its moons are really asteroids and comets that haven't been cleared from its neighborhood. The same would apply for the many asteroid/cometary moons of the Jupiter/Trojan orbital ring. And lets not forget the orbital decay of the Martian asteroid/moons Phobos & Diemos. Mars is still in the process of clearing its neighborhood.

Capping years of intense debate, astronomers resolved today to demote Pluto in a wholesale redefinition of planethood that is a victory of scientific reasoning over historic and cultural influences.

Pluto is no longer a planet.

"Pluto is dead," said Caltech researcher Mike Brown, who spoke with reporters via a teleconference while monitoring the vote. The decision also means a Pluto-sized object that Brown discovered will not be called a planet. "Pluto is not a planet. There are finally, officially, eight planets in the solar system."

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.

Pluto and its moon Charon, which would both have been planets under the initial definition proposed Aug. 16, now get demoted because they are part of a sea of other objects that occupy the same region of space. Earth and the other eight large planets have, on the other hand, cleared broad swaths of space of any other large objects.

"Pluto is a dwarf planet by the ... definition and is recognized as the prototype of a new category of trans-Neptunian objects," states the approved resolution.

Dwarf planets are not planets under the definition, however.
"There will be hundreds of dwarf planets," Brown predicted. He has already found dozens that fit the category.

Contentious logic

The vote by members of the International Astronomical Union (IAU) came after eight days of contentious debate that involved four separate proposals at the group's meeting in Prague.

The initial proposal, hammered out by a group of seven astronomers, historians and authors, attempted to preserve Pluto as a planet but was widely criticized for diluting the meaning of the word.

The category of "dwarf planet" is expected to include dozens of round objects already discovered beyond Neptune. Ultimately, hundreds will probably be found, astronomers say.

The word "planet" originally described wanderers of the sky that moved against the relatively fixed background of star. Pluto, discovered in 1930, was at first thought to be larger than it is. It has an eccentric orbit that crosses the path of Neptune and also takes it well above and below the main plane of the solar system.

Recent discoveries of other round, icy object in Pluto's realm have led most astronomers to agree that the diminutive world should never have been termed a planet.

Astronomers have argued since the late 1990s, however, on whether to demote Pluto. Public support for Pluto has weighed heavily on the debate. Today's vote comes after a two-year effort by the IAU to develop a definition. An initial committee of astronomers failed for a year to do so, leading to the formation of the second committee whose proposed definition was then redefined for today's vote.

Astronomers at the IAU meeting debated the proposals right up to the moment of the vote. Brown called the result scientifically a good decision.

"The public is not going to be excited by the fact that Pluto has been kicked out," Brown said. "But it's the right thing to do."

Rock!

I guess Earth isn't a planet, now, either, since we've got Cruithne and a few other asteroids sharing our orbit...

That leaves Venus
Orin

The definition of a planet is totally arbitrary set by arbitrary qualifiers. To satisfy as many as possible, why not set a minimum mass that includes Pluto and the need to reside within the orbits of the gas giants. In the unlikely hood a unqualified object is found at a later date that needs inclusion, make the adjustment then.

Hello All

Pluto needs to be a planet. What am I going to tell the kids.

Have to change the books now.

It appears someone else has noted the same thing that I did:

http://news.bbc.co.uk/1/hi/sci/tech/5283956.stm

And just because there may be one day a 100 objects that would have become known as planets and create a little confusion; doesn't remove them from being there. A 100 years from now when space travel is more prominent; I think astronomers will have to reclassify these objects as indeed being planets. If not sooner.
Orin

I guess this website will need to be renamed and updated

http://www.nineplanets.org/pluto.html

BMAONE23 wrote:What about the stipulation that the planetary body needs to be able to maintain an atmosphere?

Here is the Resoloution from the IAU. These is nothing about requiring an atmosphere.


RESOLUTION 5A

The IAU therefore resolves that planets and other bodies in our Solar System be defined into three distinct categories in the following way:



(1) A planet1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.



(2) A dwarf planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.



(3) All other objects3 orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".



--------------------------------------------------------------------------------



1The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

2An IAU process will be established to assign borderline objects into either dwarf planet and other categories.

3These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.



--------------------------------------------------------------------------------



RESOLUTION 5B

Insert the word "classical" before the word "planet" in Resolution 5A, Section (1), and footnote 1. Thus reading:



(1) A classical planet1 is a celestial body . . .

I have to thank ME for that reply. I hadn't seen the formal definition. So thanks to ME.

and welcome to the food chain

by the definitions though,

Saturn has millions of particles of debris within its orbital plane, although most are in orbit around it are cometary corpses and captured asteroids, they would fall into the area of it's "Local neighborhood" and by the literal definition would nulify Saturns planetary status.

Jupiter also has many captured asteroid sattalites. The local neighborhood around ite solar orbit is full of "Trojan asteroids" numbering in the 100,000's. By the definition, Jupiter is no lnoger a planet.

Mars has 2 asteroids that are doing a death spiral right now. It may be thousands of years before Diemos and Phobos are gone but they represent an unclear neighborhood as well as the asteroids from the main belt that still stray into the martian solar orbit. So Mars no longer qualifies as a planet.

Earth has many (as many as 10,000 identified) near earth objects that stray into our direct solar orbit. So I guess our "Neighborhood" isn't really cleared yet. So Earth os no longer a planet either.

By the new planet definition supplied by the IAU, Earth, Mars, Jupiter and Saturn would not qualify for planetary status as their "Neighborhoods" aren"t clear yet.

In the attached image you can see all the known debris that is still affecting the Local Neighborhoods of Earth, Mars, and Jupiter.

http://cfa-www.harvard.edu/iau/lists/InnerPlot.html

So Pluto, Ceres, and 2003 UB313 are dwarf planets. What about Charon. It was under consideration as being a binary planet with Pluto. Is it no longer even a dwarf planet? It can't be a moon, it doesn't orbit Pluto, they both orbit each other. The center of mass is somewhere between the two bodies, not inside the boundaries of Pluto.

The IAU definition says a planet must be, “nearly round.” Don’t they mean spherical? Frisbees and lampshades are round.
I see that the IAU “official domicile” is Paris, France. And that its statutes “... are published in French and English versions. In case of doubt, the French version is the only authority.” (quoting the IAU website)
I’m assuming there’s a French version of the resolution that got it right.
Can anybody read French? Who translated the resolution into English?
Oh, the mysteries of science!

The decision if you can call it that had nothing to do with science, it was all to do with the politics of a small group of astronomers.

As far as I am concerned the "IAU" is not the final authority on this subject -we the people of Earth are. I say Pluto and its MOON Charon are still on the planet list.

IAU Proposal “rejected”!!!! (pass it on )

My vote is with Large enough to be spherical shaped and orbiting a star.
Orin

I'm in favor of the new designation. I always thought that Pluto was in such an aberrant orbit, that it probably didn't form when the rest of the planets did. The orbit is highly elliptical and severely inclined to the ecliptic. In addition, although it's aprocryphal, the PL for Percival Lowell has always nagged at me. The idea of Clyde Tombaugh buttering up the boss seems likely. In addition, the upgrading of Ceres makes sense, given it's substantial size. Thanks for the opportunity to add these comments to the discussion.

Pete K

Remember now that we have entered into the era of planet hunters we must consider this carefully. We have found other LARGE planets around other stars and not all of them are on an elliptical plane -so I guess those giant Jupiter sized worlds aren't "planets" either. This is going to get ridiculous.

We will see a wide variety of types in the years to come and one must ask..... Is it large, round and does it orbit a star?

Pete K wrote:I'm in favor of the new designation. I always thought that Pluto was in such an aberrant orbit, that it probably didn't form when the rest of the planets did. The orbit is highly elliptical and severely inclined to the ecliptic. In addition, although it's aprocryphal, the PL for Percival Lowell has always nagged at me. The idea of Clyde Tombaugh buttering up the boss seems likely. In addition, the upgrading of Ceres makes sense, given it's substantial size. Thanks for the opportunity to add these comments to the discussion.

Pete K

When you stop and think about it none of the planets orbits are really circular. After all the sun is in orbit around the galaxy and therefore the planets are for half of its year going against the grain; so to speak; therefore all their orbits are more likely shaped like an e or u including Pluto and all the other objects that you don't believe were formed when the other planets were.
Did you see the Hubble photo of the star with the disc that was probably in planet formation. There were 2 discs if I recall right; one was at an angle to the other. Could be that Sol had 2 planetary discs also.
Orin

Sorry Pete I thought it was Hubble but now I cant find it. I was going to show the picture; but I cant remember where I saw it.
Orin