The definition of a planet is that gravity has made it round, and it orbits the sun rather than another planet.

I wonder what will happen if we ever discover a pair of objects the same size that would otherwise fit the definition of planet but are orbiting each other.

Though I'm not sure, I assume they've decided to adopt the arbitrary size guideline when defining a planet. If so, I wish I could be around 100 years from now when they finally make contact with the inhabitants of some distant planet... except it's not a planet because it's smaller than the size limit selected as a qualification for being classified as a planet. Oh, the diplomatic fun that will be...

"No, Ambassador. We're not insulting your home. Our astronomical guidelines dictate that an object must be over a designated size to be classified as a planet."

"So, according to your guidelines we live on an ASTEROID? How DARE you insult us in this manner!"

And thus the annihialation of humanity begins.

---

Nothing travels faster than the speed of light with the possible exception of bad news, which obeys its own special laws.
Douglas Adams (1952 - 2001)

The definition of a planet is that gravity has made it round, and it orbits the sun rather than another planet.

I wonder what will happen if we ever discover a pair of objects the same size that would otherwise fit the definition of planet but are orbiting each other.

Though I'm not sure, I assume they've decided to adopt the arbitrary size guideline when defining a planet. If so, I wish I could be around 100 years from now when they finally make contact with the inhabitants of some distant planet... except it's not a planet because it's smaller than the size limit selected as a qualification for being classified as a planet. Oh, the diplomatic fun that will be...

"No, Ambassador. We're not insulting your home. Our astronomical guidelines dictate that an object must be over a designated size to be classified as a planet."

"So, according to your guidelines we live on an ASTEROID? How DARE you insult us in this manner!"

And thus the annihialation of humanity begins.

...but, I thought that the annihilation of humanity has already begun in the Middle East... Isn't this the predicted beginning of WWIII; and thus, the "End of the World" as we know it???

D'Oh - I brought Earth politics into this Thread... <Awaiting Flogging...>

8-(

---

TimeLord04
Have TARDIS, will travel...
Come along K-9!
Join Calm Chaos

The definition of a planet is that gravity has made it round, and it orbits the sun rather than another planet.

I wonder what will happen if we ever discover a pair of objects the same size that would otherwise fit the definition of planet but are orbiting each other.

Though I'm not sure, I assume they've decided to adopt the arbitrary size guideline when defining a planet. If so, I wish I could be around 100 years from now when they finally make contact with the inhabitants of some distant planet... except it's not a planet because it's smaller than the size limit selected as a qualification for being classified as a planet. Oh, the diplomatic fun that will be...

"No, Ambassador. We're not insulting your home. Our astronomical guidelines dictate that an object must be over a designated size to be classified as a planet."

"So, according to your guidelines we live on an ASTEROID? How DARE you insult us in this manner!"

And thus the annihialation of humanity begins.

The earth isn't round - it's an oblate spheroid!

---

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

---

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

GOOD QUESTION, Mulder... ... Submit it to these "Scientists" who are making these rules and definitions and see:

1.) If they answer you...

2.) How long it takes them to answer you...

If/when they answer, let us all know so that we are all brought up to speed...

(hhhmmmm... Me-thinks that we will be waiting A LOOOOONG time for those "Scientists" to get back to him...)

LOL

;-D

---

TimeLord04
Have TARDIS, will travel...
Come along K-9!
Join Calm Chaos

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

---

Red Bull Air Racing

Gas price by zip at Seti

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

Pluto is in a different orbital plane than the eight "official" planets.

---

PROUD TO BE TFFE!

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

Pluto is in a different orbital plane than the eight "official" planets.

Good point Burr. However it's orbital plane is not in question according to 5A.

---

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

Pluto is in a different orbital plane than the eight "official" planets.

Good point Burr. However it's orbital plane is not in question according to 5A.

You are correct Mulder.

---

PROUD TO BE TFFE!

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

Pluto is in a different orbital plane than the eight "official" planets.

Good point Burr. However it's orbital plane is not in question according to 5A.

IMO 1(c) "has cleared the neighbourhood around its orbit" is exceptionally wide open and vague. Definitely an enormous number of caveats there.(Not a sentence =0)

I realize the implication is in the density of the objects in the neighborhood (Kuiper Belt objects). It's just not clearly stated. This is certain to spring more debate that in all actuality revolve around definitions that are strictly Sol centric.

Pun intended.

---

Following on from the inestimable wisdom of Mr Koenig, then The Moon should also be classed as a Planet.
I am CERTAIN that the definition of a Planet was not changed "arbitrarily". It was done by a body of people, who, with the greatest of respect ... probably (at least, on the 'balance of probability') have better qualifications to so determine.

What has happened here is that nothing has changed about Pluto, but the definition of "planet" ...

so, in fact nothing "in reality" has changed, and Mr Koenig agrees ...
Might I point out that since Pluto was discovered to be an orbiting presence, science has improved somewhat at a gallop - somewhat due to Hubble. I am certain therefore that astroscience is perfectly capable of re-aligning its thought to coincide with the best possible data availabe without input from the less well informed. Maybe you, Mr Koenig are better equipped to make the decision? Maybe therefore, you ought to apply for a job ...
Unless, that is, that in your spare time you are an astrologer! ... in which case, why did you not see this event coming?

IMO 1(c) "has cleared the neighbourhood around its orbit" is exceptionally wide open and vague. Definitely an enormous number of caveats there.(Not a sentence =0)

I realize the implication is in the density of the objects in the neighborhood (Kuiper Belt objects). It's just not clearly stated. This is certain to spring more debate that in all actuality revolve around definitions that are strictly Sol centric.

Pun intended.

You missed my point. Pluto hasn't cleared its neighborhood path, because of Charon. Sorry I spelled it wrong before.
Pluto cannot make Charon a satellite because Charon is too big.

---

Red Bull Air Racing

Gas price by zip at Seti

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

As will the earth and moon be under some hypothetical models eventually. And then no longer a planet. Along with so many celestial objects in orbit all over the universe not in orbit around the sun.

---

Ok Planetary Rules:

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 "planet"1 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 except satellites 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.


IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1


Now the debate is the following:

according to 1c if Pluto is not a planet because it has not cleared the neighborhood around it's orbit, which overlaps Neptunes orbit,

how is Neptune a planet with Pluto in it's orbit.

Neptune has clear is neighborhood. Pluto isn't in its neighborhood if it just crosses the plane of Neptune. I don't believe Pluto actually goes throught the path of Neptune where they could collide.

The problem is the binary dwarf planet of pluto ( Cheron ). It can't be a satellite because the rotational center of Pluto and Cheron is outside of the surface of Pluto.
Therefore they are a binary system.

As will the earth and moon be under some hypothetical models eventually. And then no longer a planet. Along with so many celestial objects in orbit all over the universe not in orbit around the sun.

So, here we all live on the 3Rd Rock from the Sun which by new and current definition IS NOT a planet! I love it... LOL

8-D

---

TimeLord04
Have TARDIS, will travel...
Come along K-9!
Join Calm Chaos

[quote

As will the earth and moon be under some hypothetical models eventually. And then no longer a planet. Along with so many celestial objects in orbit all over the universe not in orbit around the sun.[/quote]

The moon will always be a satellite of earth even if the spacing changes. The center of rotation of earth and moon will always stay inside the earth's surface making the earth the planet and the moon the satellite.

---

Red Bull Air Racing

Gas price by zip at Seti

[quote

As will the earth and moon be under some hypothetical models eventually. And then no longer a planet. Along with so many celestial objects in orbit all over the universe not in orbit around the sun.

The moon will always be a satellite of earth even if the spacing changes. The center of rotation of earth and moon will always stay inside the earth's surface making the earth the planet and the moon the satellite.[/quote]

I must have read my source wrong. I stand corrected on this point and would ask if you would review my research and determine what planet, or Plutonian object, this whacko I quoted is from.

---

Pluto: Down But Maybe Not Out
By Robert Roy Britt
LiveScience Managing Editor
31 August 2006



If you did not like Pluto's demotion, don't give up hope.

Arguments over the newly approved definition for "planet" are likely to continue at least until 2009, and astronomers say there is much that remains to be clarified and refined.

While it is entirely unclear if the definition could ever be altered enough to reinstate Pluto as a planet, astronomers clearly expect some changes.

In a statement today, the largest group of planetary scientists in the world offered lukewarm support for the definition, which was adopted last week by a vote of just a few hundred astronomers at the International Astronomical Union (IAU) General Assembly meeting in Prague.

Lukewarm support

The definition basically states that the eight worlds from Mercury to Neptune are planets, and that Pluto and other small round objects in the outer solar system are not planets but will be referred to as dwarf planets.

The wording has been heavily criticized as being vague and arbitrary and failing to include planets around other stars. One highly controversial aspect is the idea that a planet must control a zone of space by clearing it of other objects. In fact, Earth and some of the giant planets have not cleared their paths—asteroids cross the planetary orbits frequently and in some cases orbit in lockstep with the planets.

Nonetheless, the Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) "recognizes the authority of the IAU to render a decision," today's statement reads. "All definitions have a degree of fuzziness that requires intelligent application: what does 'round' really mean? What does it mean to 'control a zone'?"

The statement suggests there are at least three years of wrangling ahead:

"These are technical issues to be addressed by Division III of the IAU, currently chaired by Ted Bowell, a fellow DPS member. There is still work to be done, too, in constructing a definition that is generally applicable to extra-solar planetary systems. These and other changes, radical or moderate, presumably will be addressed at the next IAU General Assembly in Rio de Janeiro in 2009, and the DPS community will continue to be involved in all stages of this process.

[UPDATE 9:10 p.m. ET: A separate group of more than 300 astronomers announced today they will not use the new definition.]

Lack of authority?

Other astronomers have said or indicated that the IAU decision might not carry much weight.

David Morrison, an astronomer at NASA's Ames Research Center, was in Prague for the debates and the vote. He called the resulting definition "reasonable" but termed the IAU process "highly convoluted."

"The definition of a planet is not primarily a science issue. Scientists can (and often do) use all sorts of jargon," Morrison told SPACE.com. "This issue is of interest because non-scientists, including writers of science textbooks, want a definition. Now they have one. But it is not obvious to me that planetary scientists will adjust their terminology because of the IAU votes."

The IAU's final proposal was lambasted by many astronomers for having been slapped together at the last minute and for not adhering to recommendations from two separate committees. Morrison was on an IAU committee of astronomers that debated for months on a definition proposal. The one they adopted, Morrison said, was approved by the committee in a vote of 11-8. But it never saw the light of day. Ultimately, another committee of seven, including historians, was formed by the IAU, and the second committee's proposed definition was scrapped too, in the last moments in Prague.

"Is Pluto, then, still a planet? Yes and no," Morrison said. "The answer is semantic, based on whether dwarf planets are planets, just as dwarf pines are pines. I would say that Pluto is a planet, but it is a dwarf planet, and the first example of the class of trans-Neptunian dwarf planets."

Lack of science

The whole debate, many astronomers say, has little if anything to do with science.

Geoff Marcy, a researcher at the University of California, Berkeley, has led the discovery of dozens of planets outside our solar system. "The astrophysics of planetary bodies is so rich and complex that defining 'planet' has never been an issue under discussion among professionals," Marcy said in an email interview earlier this week.

Pressed on whether the definition made any sense, Marcy said: "It makes no scientific sense to have a definition that pertains only to our solar system and not to other planetary systems."

The DPS represents 1,300 astronomers, about a third of them from outside the United States. Today's statement included a phrase that hints at the discontent felt among many members and the likelihood that all is not said and done:

"Ultimately, the definition of a planet will come through common usage and scientific utility. There is no need to throw away current school texts; Pluto has not gone away."

---

Air Cold, the blade stops;
from silent stone,
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Calm Chaos Forums : Everyone Welcome

I still have a problem with the way these scientists went about this. Nothing changed about Pluto, only the definition was changed. It's one thing if something happened to the planet and it no longer met the definition, but the planet has not changed. Definitions are often attempts to describe what is observed to exist; once a definition is settled, changing the status of a defined object should not be dependent on a moving definition, but only on an actual change in the object. It looks like quite a few astronomers agree.

I still have a problem with the way these scientists went about this. Nothing changed about Pluto, only the definition was changed. It's one thing if something happened to the planet and it no longer met the definition, but the planet has not changed. Definitions are often attempts to describe what is observed to exist; once a definition is settled, changing the status of a defined object should not be dependent on a moving definition, but only on an actual change in the object. It looks like quite a few astronomers agree.

I disagree. Look at the history of definitions in mathematics, such as "continuous function," or even "function" itself! These things took quite some time to hash out.

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Capitalize on this good fortune, one word can bring you round ... changes.

I disagree. Look at the history of definitions in mathematics, such as "continuous function," or even "function" itself! These things took quite some time to hash out.

As long as they don't downgrade Uranus.


Regards Hans


P.S: SCNR :o)

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