Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: ariel on 24/08/2006 01:04:29
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While waiting in the airport earlier today, I looked over at someone's newspaper to see a headline stating "Pluto Is Not a Planet"...well something of the sort.
And from what I could read...it said Xena should be considered a planet, but according to scientists' definition of a planet...either pluto is not a planet...or if it does qualify as a planet...then there is also a moon that should be considered a planet as well.
ok.
im sure you can all tell...I'm quite confused and i probably have this whole story wrong. can someone inform me?
google does not seem to be helping me much...im only finding outdated information...scientists arguing if pluto was a planet in 1998...(hmm thats 8 years ago) and the article i saw...was from a recent paper!
what is the criteria scientist's use to determine whether it's a planet or not?... is there a set definition scientist's have for "planet" ?
and what about poor pluto? [:(] what is it?
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa196%2Fbariel%2Ffsm.jpg&hash=27b1c6663feeeee1f95650d42cca0927) ariel
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Mam, if you could care to click here http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=957&whichpage=8 and then scroll down from the top of the page, you will see recent article (with piccys ) all about it.
If you then scroll down even further you will come across another article (with piccys)all about further possible planets in the solar system...and then....if you scroll right to the bottom you will find some really nice pictures posted by Robert..(they have nothing to do with Pluto but are really great piccys)
Furthermore , Wikipedia discusses it also here http://en.wikipedia.org/wiki/Pluto
Men are the same as women, just inside out !
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thats exactly what i was looking for!
thanks a lot :]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa196%2Fbariel%2Ffsm.jpg&hash=27b1c6663feeeee1f95650d42cca0927) ariel
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*blushes* ..you're welcome .
Men are the same as women, just inside out !
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And from today after much deliberation Pluto has finally been declassified as a planet, there are now officially only eight planets ,tear up them school books kids.
PS dont let the teacher see.
Michael
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Mam, if you could care to click here http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=957&whichpage=8 and then scroll down from the top of the page, you will see recent article (with piccys ) all about it.
If you then scroll down even further you will come across another article (with piccys)all about further possible planets in the solar system...and then....if you scroll right to the bottom you will find some really nice pictures posted by Robert..(they have nothing to do with Pluto but are really great piccys)
Furthermore , Wikipedia discusses it also here http://en.wikipedia.org/wiki/Pluto
Men are the same as women, just inside out !
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thats exactly what i was looking for!
thanks a lot :]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa196%2Fbariel%2Ffsm.jpg&hash=27b1c6663feeeee1f95650d42cca0927) ariel
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*blushes* ..you're welcome .
Men are the same as women, just inside out !
-
And from today after much deliberation Pluto has finally been declassified as a planet, there are now officially only eight planets ,tear up them school books kids.
PS dont let the teacher see.
Michael
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oh no! now...
my very educated mother just served us nine _____.....
NINE WHATTT??
wah :[
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa196%2Fbariel%2Ffsm.jpg&hash=27b1c6663feeeee1f95650d42cca0927) ariel
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The new definition of a planet is "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."
Pluto is called a dwarf planet now.
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I just heard about this today and was in shock...thanks for the additonal info Neil...Pluto is really an orphan planet is no longer has a family....
"Lo" Loretta
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This is unbeleivable.
Love you lots
Helena xxx
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Mam, if you could care to click here http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=957&whichpage=8 and then scroll down from the top of the page, you will see recent article (with piccys ) all about it.
If you then scroll down even further you will come across another article (with piccys)all about further possible planets in the solar system...and then....if you scroll right to the bottom you will find some really nice pictures posted by Robert..(they have nothing to do with Pluto but are really great piccys)
Furthermore , Wikipedia discusses it also here http://en.wikipedia.org/wiki/Pluto
Men are the same as women, just inside out !
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thats exactly what i was looking for!
thanks a lot :]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa196%2Fbariel%2Ffsm.jpg&hash=27b1c6663feeeee1f95650d42cca0927) ariel
-
*blushes* ..you're welcome .
Men are the same as women, just inside out !
-
And from today after much deliberation Pluto has finally been declassified as a planet, there are now officially only eight planets ,tear up them school books kids.
PS dont let the teacher see.
Michael
-
oh no! now...
my very educated mother just served us nine _____.....
NINE WHATTT??
wah :[
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa196%2Fbariel%2Ffsm.jpg&hash=27b1c6663feeeee1f95650d42cca0927) ariel
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The new definition of a planet is "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."
Pluto is called a dwarf planet now.
-
I just heard about this today and was in shock...thanks for the additonal info Neil...Pluto is really an orphan planet is no longer has a family....
"Lo" Loretta
-
This is unbeleivable.
Love you lots
Helena xxx
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http://news.bbc.co.uk/1/hi/sci/tech/5283956.stm
quote:
A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet.
On Thursday, experts approved a definition of a planet that demoted Pluto to a lesser category of object.
But the lead scientist on Nasa's robotic mission to Pluto has lambasted the ruling, calling it "embarrassing".
And the chair of the committee set up to oversee agreement on a definition implied that the vote had effectively been "hijacked".
The vote took place at the International Astronomical Union's (IAU) 10-day General Assembly in Prague. The IAU has been the official naming body for astronomy since 1919.
Only 424 astronomers who remained in Prague for the last day of the meeting took part.
An initial proposal by the IAU to add three new planets to the Solar System - the asteroid Ceres, Pluto's moon Charon and the distant world known as 2003 UB313 - met with considerable opposition at the meeting. Days of heated debate followed during which four separate proposals were tabled.
Eventually, the scientists adopted historic guidelines that see Pluto relegated to a secondary category of "dwarf planets".
Drawing the line
Dr Alan Stern, who leads the US space agency's New Horizons mission to Pluto and did not vote in Prague, told BBC News: "It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons.
"Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups'.
"Secondly, the actual definition is even worse, because it's inconsistent."
One of the three criteria for planethood states that a planet must have "cleared the neighbourhood around its orbit". The largest objects in the Solar System will either aggregate material in their path or fling it out of the way with a gravitational swipe.
Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune.
But Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path.
These rocks are all essentially chunks of rubble left over from the formation of the Solar System more than four billion years ago.
"If Neptune had cleared its zone, Pluto wouldn't be there," he added.
Stern said like-minded astronomers had begun a petition to get Pluto reinstated. Car bumper stickers compelling motorists to "Honk if Pluto is still a planet" have gone on sale over the internet and e-mails circulating about the decision have been describing the IAU as the "Irrelevant Astronomical Union".
'Inconvenient arrangements'
Owen Gingerich chaired the IAU's planet definition committee and helped draft an initial proposal raising the number of planets from nine to 12.
The Harvard professor emeritus blamed the outcome in large part on a "revolt" by dynamicists - astronomers who study the motion and gravitational effects of celestial objects.
"In our initial proposal we took the definition of a planet that the planetary geologists would like. The dynamicists felt terribly insulted that we had not consulted with them to get their views. Somehow, there were enough of them to raise a big hue and cry," Professor Gingerich said.
"Their revolt raised enough of a fuss to destroy the scientific integrity and subtlety of the [earlier] resolution."
He added: "There were 2,700 astronomers in Prague during that 10-day period. But only 10% of them voted this afternoon. Those who disagreed and were determined to block the other resolution showed up in larger numbers than those who felt 'oh well, this is just one of those things the IAU is working on'."
E-voting
Professor Gingerich, who had to return home to the US and therefore could not vote himself, said he would like to see electronic ballots introduced in future.
Alan Stern agreed: "I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room - you can't even claim consensus.
"If everyone had to travel to Washington DC every time we wanted to vote for President, we would have very different results because no one would vote. In today's world that is idiotic. I have nothing but ridicule for this decision."
He added that he could not see the resolution standing for very long and did not plan to change any of the astronomy textbook he was currently writing.
But other astronomers were happy to see Pluto cast from the official roster of planets. Professor Iwan Williams, the IAU's president of planetary systems science, commented: "Pluto has lots and lots of friends; we're not so keen to have Pluto and all his friends in the club because it gets crowded.
"By the end of the decade, we would have had 100 planets, and I think people would have said 'my goodness, what a mess they made back in 2006'."
Shaking hands
Robin Catchpole, of the Institute of Astronomy in Cambridge, UK, said: "My own personal opinion was to leave things as they were. I met Clyde Tombaugh, who discovered Pluto, and thought, it's nice to shake hands with someone who discovered a planet.
"But since the IAU brought out the first draft resolution, I was rather against that because I thought it was going to be very confusing. So the best of the alternatives was to keep the eight planets as they are, and then demote Pluto. I think this is a far superior solution."
The need for a strict definition was deemed necessary after new telescope technologies began to reveal far-off objects that rivalled Pluto in size.
The critical blow for Pluto came with the discovery three years ago of an object currently designated 2003 UB313. Discovered by Mike Brown and colleagues at the California Institute of Technology, 2003 UB313 has been lauded by some as the "10th Planet".
Measurements by the Hubble Space Telescope show it to have a diameter of 3,000km (1,864 miles), a few hundred km more than Pluto. 2003 UB313 will now join Pluto in the dwarf planet category.
Mike Brown seemed happy with Pluto's demotion. "Eight is enough," he told the Associated Press, jokingly adding: "I may go down in history as the guy who killed Pluto."
George
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what was wrong with the old definition? why does anyone care about the enumeration of the "number of planets?" back in my day, asteroids and comets and whatnot were also considered planets, because they fit the clear definition of planet. changing the definition to include/exclude certain bodies arbitrarily is juvenile. by all clear reasoning, if you must draw the line between major and minor planets, the best way to do it is to consider jupiter, saturn, uranus and neptune as "major planets" and everything else as "minor planets."
am i the only person thinking this "number of planets" thing is bunk?
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quote:
Originally posted by bostjan
what was wrong with the old definition? why does anyone care about the enumeration of the "number of planets?" back in my day, asteroids and comets and whatnot were also considered planets, because they fit the clear definition of planet. changing the definition to include/exclude certain bodies arbitrarily is juvenile. by all clear reasoning, if you must draw the line between major and minor planets, the best way to do it is to consider jupiter, saturn, uranus and neptune as "major planets" and everything else as "minor planets."
am i the only person thinking this "number of planets" thing is bunk?
Comets are clearly functionally distinct from planets (although it may be argued that one can envision and entity that has characteristics somewhere between a comet and a planet, but as yet, I have not heard of such a thing).
In a way, the number of planets is arbitrary, and what is a planet is arbitrary. What is significant (in a psychological sense, not in a physical one) is the number of uniquely named solar satellites (if one tried to give every rock and asteroid its own name, you would quickly run out of names).
Beyond that, one might also suggest that some planets have a historic significance in that the ancients knew about them, and could see them with the naked eye. This ofcourse has to take into account not only the size of the satellite, but also its closeness to Earth, and the amount of light it reflects.
George
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yeah, but just pick up an old (early 1990's or before) astronomy book and look up "planet," and you'll see what i mean. a planet used to be any solid object revolving around the sun. this definition was fine with me. planets were further divided into major planets and minor planets. this was rather pointless, since the older books defined the major planets by naming and listing them and saying that anything else was a minor planet. perhaps all of my textbooks came from the same messed-up source, though. who knows, but the argument is semantic.
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I and I believe most astronomers agree that a planet is a body orbiting a star that is big enough to clear all smaller debris from its orbital area. The planets from Mercury to Neptune have done this. The minor planets between Mars and Jupiter are not big enough to do this although it is likely that they were a few larger bodies at one time that eventually collided and broke into bits.
Pluto is just a member of a whole group of similar minor planets mostly outside the orbit of neptune but is rather special in that it is strongly associated with Neptune and in an orbit in resonance with it and so could be considered as a possible "lost moon" of neptune
Learn, create, test and tell
evolution rules in all things
God says so!
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What about debris that orbits in the Lagrange points of the "planet?" Is there a special case to exclude them? Otherwise, nothing would be a planet, as Alan Stern pointed out.
This is a very valid point that needs to be addressed.
I am unhappy with any definition that deals with the existance of debris or not, since it cannot be determined that there is no debris.
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You are being pedantic. Obviously there are smaller objects orbiting in similar and crossing orbits to a planet by debris I mean major objects of similar size to the "planet" orbiting in a very similar orbit.
It is quite possible to have many minor planet sized objects orbiting together in similar orbits and have them stable for many thousands of millions of years but one object the size of the earth would have a strong enough gravitiational field either to crash into them or eject them from the area quite quickly so a planet is a lump that is big enough to have some control over its local environment.
Learn, create, test and tell
evolution rules in all things
God says so!
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so is the definition of a plent to be, from now on, a body orbiting a star with a mass small enough not to be able to fuse hydrogen, yet big enough to be rounded by it's own gravity and that it must be the largest object in it's orbital path? from what i've read in the news, and online, they never mentioned that objects cleared had too be of similar size.
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yeah, but just pick up an old (early 1990's or before) astronomy book and look up "planet," and you'll see what i mean. a planet used to be any solid object revolving around the sun. this definition was fine with me. planets were further divided into major planets and minor planets. this was rather pointless, since the older books defined the major planets by naming and listing them and saying that anything else was a minor planet. perhaps all of my textbooks came from the same messed-up source, though. who knows, but the argument is semantic.
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I and I believe most astronomers agree that a planet is a body orbiting a star that is big enough to clear all smaller debris from its orbital area. The planets from Mercury to Neptune have done this. The minor planets between Mars and Jupiter are not big enough to do this although it is likely that they were a few larger bodies at one time that eventually collided and broke into bits.
Pluto is just a member of a whole group of similar minor planets mostly outside the orbit of neptune but is rather special in that it is strongly associated with Neptune and in an orbit in resonance with it and so could be considered as a possible "lost moon" of neptune
Learn, create, test and tell
evolution rules in all things
God says so!
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What about debris that orbits in the Lagrange points of the "planet?" Is there a special case to exclude them? Otherwise, nothing would be a planet, as Alan Stern pointed out.
This is a very valid point that needs to be addressed.
I am unhappy with any definition that deals with the existance of debris or not, since it cannot be determined that there is no debris.
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You are being pedantic. Obviously there are smaller objects orbiting in similar and crossing orbits to a planet by debris I mean major objects of similar size to the "planet" orbiting in a very similar orbit.
It is quite possible to have many minor planet sized objects orbiting together in similar orbits and have them stable for many thousands of millions of years but one object the size of the earth would have a strong enough gravitiational field either to crash into them or eject them from the area quite quickly so a planet is a lump that is big enough to have some control over its local environment.
Learn, create, test and tell
evolution rules in all things
God says so!
-
so is the definition of a plent to be, from now on, a body orbiting a star with a mass small enough not to be able to fuse hydrogen, yet big enough to be rounded by it's own gravity and that it must be the largest object in it's orbital path? from what i've read in the news, and online, they never mentioned that objects cleared had too be of similar size.
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I really think they should send Pluto a certificate or something and make it an honorary planet...after all..it's been generally accepted as one for a long time.
...akin to an honorary degree !
I'll deliver it..I'm good at holding my breath !!
Men are the same as women, just inside out !