It's official: IAU says Pluto is a "plutoid"

[JonathanN]

Good morning all,

Well, it's official. The International Astronomical Union has declared that objects like Pluto and Eris are henceforth to be known as "plutoids".

This'll put the cat amongst the pigeons . . . sorry, I meant plutinos amongst the asteroids.

Details at www.spaceinfo.com.au/iau20080612.html

Regards,

Jonathan


Jonathan Nally
Editor
SpaceInfo.com.au
www.spaceinfo.com.au

[renormalised (Carl)]

How imaginative can you get.....plutoid. Must've taken all of 100 days for them to figure that one out

They should've given the naming rights to a bunch of primary school kids. At least they would've come up with something a bit more interesting and imaginative!!!

[madtuna (Steve)]

Just thank your lucky stars Pluto wasn't originally named after some mythical god named Hemmer..else we'd be in a real pickle trying to rename the damn thing about now!

[renormalised (Carl)]

Originally Posted by madtuna

Just thank your lucky stars Pluto wasn't originally named after some mythical god named Hemmer..else we'd be in a real pickle trying to rename the damn thing about now!

There wouldn't be enough cream in every pharmacy on this planet to sooth that one!!!

[bojan]

:rofl :

Originally Posted by madtuna

Just thank your lucky stars Pluto wasn't originally named after some mythical god named Hemmer..else we'd be in a real pickle trying to rename the damn thing about now!

[Ian Robinson]

I don't care what that say it will be called , as far as I'm concerned it was and remains , a planet.

The guys in that committee need to get onto more important issues.

[Geoff45 (Geoff)]

Originally Posted by Ian Robinson

I don't care what that say it will be called , as far as I'm concerned it was and remains , a planet.

The guys in that committee need to get onto more important issues.

Well, once upon a time the sun and the moon were regarded as planets--the word means "wanderer". The earth, being thought of as the centre of the universe wasn't a planet. I'm sure after Galileo came along there were still people who remained true to the idea that the sun and the moon were planets, no matter what they were called.

Definitions may change in the light of new knowledge.

[[1ponders] (Paul)]

[stephend]

Usually when some group wants to change the language there's some obvious political ambition behind it. You see it all the time. It can be annoying coz it's transparent manipulation but people fall for it.

In this case I can't see any covert motive, can you? Except of course that people on committees like to make sensational decisions. It's called attention seeking and even kids do it.

Pluto is about 5% as massive as Venus but it is fully half as big in terms of diameter. It's kind of spherical and it goes 'round the sun and even has its own moons - sounds like a planet to me.

IAU's definition is that a planet must clear the space around its orbit. I don't think this is a very clever definition coz how do you define "clear"?

[renormalised (Carl)]

Originally Posted by stephend

...IAU's definition is that a planet must clear the space around its orbit. I don't think this is a very clever definition coz how do you define "clear"?

Precisely. By their definition, Jupiter isn't a planet. It most certainly hasn't cleared its orbit of debris.....how, then, do they explain the trojan asteroids in its orbit??. Nor has Mars, or Earth. So, where do we start??

This was originally a rushed decision, made by a small number of astronomers at the IAU conference after most of the delegates went home.

It should be changed.

[Ric]

I really think that the IAU boffins need to get their Tascos out and get into some visual observing, I really think that they have lost touch with everything.

Cheers

[okiscopey (Mike)]

Extracts from: http://news.bbc.co.uk/2/hi/science/nature/7449735.stm

"Plutoid" is the word of the moment for astronomers.

It is the new classification that has been sanctioned for the object that was formerly known as the "ninth planet".

It is nearly two years since the International Astronomical Union (IAU) stripped Pluto of its former status as a "proper" planet.

Now an IAU committee, meeting in Oslo, has suggested that small, nearly spherical objects orbiting beyond Neptune should carry the "plutoid" tag.

As astronomy's official nomenclature organisation, the IAU must approve all new names and classifications.

Its decision at the 2006 General Assembly to demote Pluto from "planet" to "dwarf planet" caused an international furore.

(etc)

Ceres will not be considered a plutoid because of its position in the asteroid belt between Mars and Jupiter.

The classification will not placate those incensed by Pluto's demotion.

Alan Stern, a former Nasa space sciences chief and principal investigator on a mission to Pluto, was scathing in his condemnation of the IAU.

"It's just some people in a smoke-filled room who dreamed it up," he told the Associated Press. "Plutoids or haemorrhoids, whatever they call it. This is irrelevant."

[stephend]

I think you are suggesting the whole thing needs to be renormalised?!

One perspective that might help is to imagine that Pluto's orbit was between Venus's and Earth's. If that were so, is it conceivable that someone would say "Venus is a planet and so is Earth but Pluto is not"?

Another: Compare and contrast Jupiter and Earth. Are they similar in size? No. Are they similar in make-up? No. Then what do they have in common that puts them in the same "planet" category?
1) They both formed from material in sol's original accretionary disk
2) They are both egregiously big

Point (1) applies to just about everything, from long-orbit comets to asteroids. So it comes down to size.

So how do you decide whether a planet-like object is big enough to warrant calling it a planet? If there are no objective criteria, I suggest a specialist committe is not qualified to say. It becomes a "common sense" thing and you need to cast a very wide net to get a feeling of what the common sense of a thing is.

[madtuna (Steve)]

So will Ceres remain a dwarf planet or will they reclassify it too?

[Dog Star (Phil)]

I grew up being taught that Pluto was a planet. The decision to re classify it as a dwarf planet was not personally welcomed by me but after seeing diagrams of its orbit around the Sun as compared to the other planets, i felt compelled to admit that there was indeed something "different" about Pluto. I have in fact been trying to get used to the idea of referring to it as a dwarf planet. What I will NOT do, by God, is call it a "plutoid"!

[JonathanN]

Like others, I have a sentimental attachment to historical ideas about Pluto.

But I'm not upset by the new 'plutoid' description. It is no different to referring to Mercury, Venus, Earth and Mars as 'terrestrial planets', or Jupiter, Saturn, Uranus and Neptune as 'gas giants'. (And yes, I know there are finer distinctions regarding the gas giants, eg. 'ice giants'.)

It's just a description. :-)

Cheers,

Jonathan


Jonathan Nally
Editor
SpaceInfo.com.au
www.spaceinfo.com.au

[renormalised (Carl)]

It might be a description, Jonathan, bit it's an awfully lame one!!!. Would you call the giant planets "Jovoids" or "Giantoids" or the terrestrial planets "Earthoids" or "Rockoids".....I don't think so

I think the guys who suggested this name for Pluto type objects were "dumboids"

[Trido (Justin)]

Listen to the Astronomy 161 podcast if you're so confused/unwilling to acknowledge the fact that Pluto is not a planet. It speaks at length on the differences.

Also, Astronomy is a science. Science is about challenging what you believe in and not being dogmatic. That is why Religion and Science can never peacefully coexist.

EDIT: Although Plutoid? Really dodgy IMO. I thought Dwarf Planet was fine.

[stephend]

If it isn't a planet, then obviously we can't call it a "dwarf planet".

I don't think anyone in this debate is being "dogmatic". Rather, some are challenging the criteria promoted by a certain subset of scientists.

Rather than invoking the great god "Astronomy 161 podcast", how about some actual dialectic?

By the way, science and religion very often co-exist peacefully, most notably, perhaps, in the intellect of Isaac Newton.

[Dog Star (Phil)]

What a wonderfully succinct reply, Stephend.
Seems to me that this debate (Status of Pluto) has a slight bias toward nomenclature as opposed to actual science, but I'll cheerfully admit that I'm a gob****e.