Pluto is NOT a Planet
Comments(20)
However, it is a dwarf planet as is Ceres, but they don’t count.
Resolution 5a passes and we now have 8 planets (again).
The resolution:
1) A planet is a celestial body that (a) is by far the largest object in its local population [1], (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) does not produce energy by any nuclear fusion mechanism [3]. (2) According to point (1) the eight classical planets discovered before 1900, which move in nearly circular orbits close to the ecliptic plane are the only planets of our Solar System. All the other objects in orbit around the Sun are smaller than Mercury. We recognize that there are objects that fulfill the criteria (b) and (c) but not criterion (a). Those objects are defined as “dwarf” planets. Ceres as well as Pluto and several other large Trans-Neptunian objects belong to this category. In contrast to the planets, these objects typically have highly inclined orbits and/or large eccentricities. (3) All the other natural objects orbiting the Sun that do not fulfill any of the previous criteria shall be referred to collectively as “Small Solar System Bodies”.[4]
[1] The local population is the collection of objects that cross or close approach the orbit of the body in consideration.
[2] This generally applies to objects with sizes above several hundreds km, depending on the material strength.
[3] This criterion allows the distinction between gas giant planets and brown dwarfs or stars.
[4] This class currently includes most of the Solar System asteroids, near-Earth objects (NEOs), Mars-, Jupiter- and Neptune-Trojan asteroids, most Centaurs, most Trans-Neptunian Objects (TNOs), and comets.
Update: You can listen to some of the discussion and voting on the Jodcast link below.
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IAU MEETING LINKS
The Jodcast — podcasting from the meeting! Catch the good interviews they’ve done already. BY THE WAY — The Jodcast is more than just a podcast, you will find links to the meeting I didn’t include. Go in and explore (especially the first link on the main page) you will see how much is really going on. Be sure to check these out!
Thomas Marquarts IAU Blog — Blogging the event, this site reportedly won’t be up long so have a look.
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Clyde Tombough must be turning in his grave right now!I think they drop the ball on this one.
This is a sad day in astronomy land.
LONG LIVE PLUTO!!!!!
for 53 years this has been a planet to me and will allways be.
Dropped the ball? Explain.
This is the essence of “good science.” Sure, at the time of Pluto’s discovery it was logical that it was a planet. Now with better technologies and many new discoveries it is obvious that Pluto is NOT a planet and the scientific community must be able to acknowledge that.
This goes along with the theories of Evolution and Strings. If scientists are just supporting evidence that a hypothosis is true (or false) instead of observing all data, then “scientific fact” becomes no different than a faith or a philosophy.
I totally agree Jarad…did we keep the notion that the world was flat just EVERYONE believed that for eons?? Did we keep the notion that the universe revolved around the earth just because EVERYONE learned that in cave school??
Science progresses what we “know”. Sure, long live Pluto, but live as a “Dwarf” planet it must!!
After a lot of work this afternoon, we have edited down the IAU session voting on the four proposals (5a, 5b, 6a, 6b) to a more compact and manageable 22 minutes. We have still kept in many of the questions that were asked by astronomers in the hall. The results are now on the Jodcast for you to listen to.
It’s sort of sad but I’m satisfied that justice has been done. If nothing else comes from this announcement at least we’ll all know the name of the largest asteroid (Ceres) and that there are other dwarf planets in the outer solar system. Ought to make for a good “Jeopardy” question (?answer?)
Oh very good Stuart! Taking out the vote counts alone must have sped things up a lot
It sure did! It is now less than a quarter the length of the original. The editing isn’t brilliant but we wanted a quick turn around! I left in some of the joking around the vote results though as it amused me.
[...] [Addendum] For loads of more information, please check out the IAU General Assembly Special 2006 at The Jodcast (via the comments at Tom’s Astronomy Blog: Pluto is NOT a Planet). [...]
Some of it was pretty amusing.
“Clyde Tombough must be turning in his grave right now!”
Unlikely. His widow was quoted as saying he’d probably have accepted the decision. His last words on Pluto were, “It’s there. Whatever it is. It is there.”
It just seems odd to me that we are spending time looking for planets orbiting other stars (at last count about 200 have been found), but astronomers decided to remove one orbiting our own.
Yes, there is much eccentric about Pluto’s orbit, but there is also much eccentric about Jupiter’s rotation, Uranus’s orientation to the Sun, and much eccentric about Earth’s lifeforms … and some of them even have PhD’s.
I’m on the fence. On one hand I applaud a serious attempt to define once and for all (!) what a planet ‘is’ . . but . . .a)I grew up with 9 planets and unscientific or not I wish it to stay and b)if it orbits the sun, has a moon of its own, and is bigger than a mountain, shouldn’t it be classified as a planet, dwarf or not?
BTW – any way to increase the font size of the comments? I had to copy and paste the text to read it. Still love the site Tom
Hey young feller (Slapinions) long time no hear. I FINALLY did figure out where to make the change so comments are bigger.
They should just leave Pluto a planet. When you were in school you were taught that there were 9 planets not 8. How is the poem that was made up for you to remember all the planets ( My Very Educated Mother Just Sold my Uncle Neds Parrot) going to sound.
I have no doubt that the newly accepted definition for ‘planet’ will have to be revisited. Some poeple objected to the first draft as ‘too complicated’. Some objected that ‘it will be difficult to determine the size accurately’ or some such. Well, given that ‘clearing the orbital space’ requires knowning all of the junk that’s there, just knowing the size seems easy. Further, given that some 10,000 objects cross Earth’s orbit, it seems to me that we’ll soon realize that Earth isn’t a planet after all. I look out my window, and Earth is looking pretty flat.
I like, and agree with that last comment. 100%….. way to go stephen =)
OMG! I hate how NASA randomly decided that Pluto is not a planet anymore!!!!!! F*** that!
Well actually NASA didn’t decide that. The decision was from a vote by the International Astronomical Union.