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Fight for Pluto !, A Campaign to Reverse the Unjust Demotion
mars loon
post Aug 24 2006, 08:24 PM
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Dear Friends,

Today I am extremely dissapointed that the Pluto Demoters have triumphed.

I respect their opinion, but disagree with it.

I strongly agree with Alan Stern's statement calling it "absurd" that only 424 astronomers were allowed to vote, out of some 10,000 professional astronomers around the globe.

This tiny group is clearly not at all representative by mathematics alone.

I believe we should formulate a plan to overturn this unjust decision and return Pluto to full planetary status, and as the first member of a third catagory of planets, Xena being number two. Thus a total of 10 Planets in our Solar System

Please respond if you agree that Pluto should be restored as a planet.

ken

Ken Kremer
Amateur Astronomers Association of Princeton
Program Chairman
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Stephen
post Aug 25 2006, 11:23 AM
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Too many of the elements in the IAU's definition are inherently flawed. Curiously that includes the very one that many people may have the least problem with: ""A planet is a celestial body that (a) is in orbit around the Sun".

Just exactly how do you determine that body goes round the Sun? In many cases the answer is doubtless obvious. However, as with so much else in the universe there are always exceptions. One particularly bizarre example of such an exception is object J002E3, which paid a visit to our vicinity a few years ago. It is believed to be the spent 3rd stage of one of the Apollo missions. Its orbit is such that although it usually goes round the Sun it can perodically be captured by the Earth, orbit it for a while, then escape back into solar orbit again.

A more pertinent example of an exception, though, is Earth's own Moon. Apparently the Sun's gravitation field has a stronger pull on the Moon than the Earth's own field. (For more check out here and here; for a more explicitly worked out version of the maths check out here; and there's an interesting discussion of the problem, together with lots of maths, here; while this page puts a more democratic perspective on the issue: "the moon co-orbits the sun with the earth".)

Since the IAU chose not to define the yardstick(s) on which it determines when a body is in orbit around the Sun (and when it isn't), there seems no reason the balance of gravitation forces could not be used as that yardstick. Yet were that yardstick applied to the Moon it could be used as the basis for arguing that since the Sun has a stronger pull on the Moon than the Earth's own gravitation field, the Moon is therefore (technically) in effect going round the Sun rather than around the Earth and thus (technically) not a moon under the IAU resolution but either a planet or a dwarf planet (depending on the other elements in the definitions). huh.gif

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dilo
post Aug 25 2006, 08:26 PM
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advice: this post is OT here! sorry for this...
QUOTE (Stephen @ Aug 25 2006, 12:23 PM) *
A more pertinent example of an exception, though, is Earth's own Moon. Apparently the Sun's gravitation field has a stronger pull on the Moon than the Earth's own field. (For more check out here and here; for a more explicitly worked out version of the maths check out here; and there's an interesting discussion of the problem, together with lots of maths, here; while this page puts a more democratic perspective on the issue: "the moon co-orbits the sun with the earth".)

Stephen, I must confess that I ignored that ratio between the gravity force from Earth and from Sun is below 1 only for our moon!
Your links are very interesting and, apparently, all figures are right but... while math is right, there is a big flaw in the physics of all of them!
In fact, they forget that Earth-Moon system is not inertial! You cannot ignore that the Earth-Moon baricenter is moving in a circular trajectory, so there are other forces that must be considered in the game, especially the centrifugal force, which is equal to Sun gravity in the baricenter (but, obviously, points in the opposite direction).
The proof of how wrong are conclusions arising from application of inertial rules to such a rotating system is the question posed in the math forum you posted: the asking guy calculated that the equilibrium point between Sun and Earth gravity is about 258000 Km from Earth, so he wonder how the Moon can still orbiting the Earth from a larger distance.
But it is well known that the equilibrium (Lagrange) points are located 1.5 million Km from the Earth, 6 times away and well behind Moon orbit. This result can be ontained only considerning also centrifugal force arising from the rotation around the Sun.
In conclusion, when two body are gravitationally linked (and Earth-Moon are linked without any doubt), you must first consider their movement around their common baricenter and, before to consider Sun attraction, you must subctract the motion of the baricenter around the Sun. All residual forces are very small and can be considered tidal forces or second-order rotational effects...


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Posts in this topic
- mars loon   Fight for Pluto !   Aug 24 2006, 08:24 PM
- - Holder of the Two Leashes   I'm in.   Aug 24 2006, 08:37 PM
- - volcanopele   So am I.   Aug 24 2006, 08:48 PM
- - JRehling   QUOTE (mars loon @ Aug 24 2006, 01:24 PM)...   Aug 24 2006, 08:49 PM
|- - David   QUOTE (JRehling @ Aug 24 2006, 08:49 PM) ...   Aug 24 2006, 09:00 PM
|- - Stephen   QUOTE (JRehling @ Aug 24 2006, 08:49 PM) ...   Aug 25 2006, 09:22 AM
|- - Ames   QUOTE (Stephen @ Aug 25 2006, 10:22 AM) Y...   Aug 25 2006, 11:10 AM
|- - Stephen   QUOTE (Ames @ Aug 25 2006, 11:10 AM) Ok t...   Aug 25 2006, 11:50 AM
- - DonPMitchell   I agree, this is an arbitrary ruling by a small su...   Aug 24 2006, 09:05 PM
|- - Planet X   At any rate, I'm in! What if it turns out...   Aug 24 2006, 09:19 PM
||- - mars loon   QUOTE (Planet X @ Aug 24 2006, 09:19 PM) ...   Aug 24 2006, 10:18 PM
|||- - Jyril   QUOTE (mars loon @ Aug 25 2006, 01:18 AM)...   Aug 24 2006, 10:58 PM
||- - tedstryk   This could really get messy if they find a Pluto-t...   Aug 24 2006, 10:20 PM
||- - Alan Stern   Poll at chicagotribune.com... Do you agree with t...   Aug 24 2006, 10:32 PM
||- - Jyril   QUOTE (Alan Stern @ Aug 25 2006, 01:32 AM...   Aug 24 2006, 11:03 PM
||- - mars loon   QUOTE (Alan Stern @ Aug 24 2006, 10:32 PM...   Aug 24 2006, 11:48 PM
||- - dilo   I fully understand Alan is hungry, but, apart hist...   Aug 25 2006, 08:16 AM
||- - chris   QUOTE (dilo @ Aug 25 2006, 09:16 AM) I fu...   Aug 25 2006, 08:35 AM
|||- - dilo   QUOTE (chris @ Aug 25 2006, 09:35 AM) Did...   Aug 25 2006, 10:00 AM
||- - djellison   QUOTE (dilo @ Aug 25 2006, 09:16 AM) NEO ...   Aug 25 2006, 08:49 AM
||- - JRehling   QUOTE (dilo @ Aug 25 2006, 01:16 AM) I fu...   Aug 25 2006, 03:32 PM
||- - David   QUOTE (JRehling @ Aug 25 2006, 03:32 PM) ...   Aug 25 2006, 03:58 PM
|- - David   QUOTE (DonPMitchell @ Aug 24 2006, 09:05 ...   Aug 24 2006, 09:44 PM
- - Jyril   If you don't like Pluto's demotion, consid...   Aug 24 2006, 09:10 PM
- - Decepticon   I for one cheered when I heard the news! I su...   Aug 25 2006, 12:30 AM
- - David   If it had been up to me, personally, to make a dec...   Aug 25 2006, 03:10 AM
- - alan   I would have been happy with either of the possibi...   Aug 25 2006, 03:28 AM
- - Myran   Science isnt something that you can start a politi...   Aug 25 2006, 03:42 AM
|- - tedstryk   QUOTE (Myran @ Aug 25 2006, 03:42 AM) Sci...   Aug 25 2006, 04:18 AM
- - Betelgeuze   Im in! I dont mind if Pluto is a dwarf planet...   Aug 25 2006, 05:09 AM
|- - JRehling   C - ommittee to R - einstate A - stronomy's P ...   Aug 25 2006, 05:45 AM
- - djellison   The classification of Pluto as non-planetary doesn...   Aug 25 2006, 08:11 AM
- - djellison   Truth be told - I think we should be fighting for ...   Aug 25 2006, 10:12 AM
|- - Jyril   QUOTE (djellison @ Aug 25 2006, 01:12 PM)...   Aug 25 2006, 12:00 PM
|- - djellison   QUOTE (Jyril @ Aug 25 2006, 01:00 PM) Acc...   Aug 25 2006, 12:11 PM
|- - David   QUOTE (Jyril @ Aug 25 2006, 12:00 PM) The...   Aug 25 2006, 12:26 PM
- - Patteroast   The two results I was hoping for were either a def...   Aug 25 2006, 11:09 AM
- - Stephen   Too many of the elements in the IAU's definiti...   Aug 25 2006, 11:23 AM
|- - dilo   advice: this post is OT here! sorry for this.....   Aug 25 2006, 08:26 PM
- - Jyril   I have no problems with the "orbital dominanc...   Aug 25 2006, 12:28 PM
- - odave   Jupiter: "Dangit, I was just about to become...   Aug 25 2006, 04:00 PM
- - David   Radicalized pro-Plutonians may find this site amus...   Aug 26 2006, 05:15 PM
|- - mars loon   QUOTE (David @ Aug 26 2006, 05:15 PM) Rad...   Aug 26 2006, 08:50 PM
|- - volcanopele   QUOTE (David @ Aug 26 2006, 10:15 AM) Rad...   Aug 26 2006, 09:44 PM
|- - vexgizmo   QUOTE (David @ Aug 26 2006, 10:15 AM) Rad...   Aug 29 2006, 05:53 AM
|- - karolp   QUOTE (vexgizmo @ Aug 29 2006, 07:53 AM) ...   Aug 30 2006, 01:46 PM
|- - mars loon   QUOTE (karolp @ Aug 30 2006, 01:46 PM) Th...   Sep 2 2006, 01:42 PM
|- - karolp   If I were a US scientist I would put forward a pet...   Sep 2 2006, 02:40 PM
|- - tedstryk   QUOTE (mars loon @ Sep 2 2006, 01:42 PM) ...   Sep 13 2006, 09:45 PM
- - marsman   Here is a news article from CNN about an actual pr...   Sep 2 2006, 04:21 PM
- - volcanopele   Even the California Legislature is now weighing in...   Sep 7 2006, 08:12 PM
- - odave   Now that is an excellent example of government in ...   Sep 8 2006, 12:17 PM
- - Greg Hullender   volcanopele: Aren't you worried that it suppor...   Sep 9 2006, 04:05 AM
- - DonPMitchell   The last issue of Nature has an article about the ...   Sep 9 2006, 05:15 AM
|- - gpurcell   Absolutely, it was a political hatchet job from st...   Sep 13 2006, 06:58 AM
- - Sedna   Even when discovered, it was doubted that Pluto wa...   Sep 14 2006, 10:48 PM
|- - JRehling   QUOTE (Sedna @ Sep 14 2006, 03:48 PM) Eve...   Sep 15 2006, 04:41 AM
|- - Rob Pinnegar   QUOTE (JRehling @ Sep 14 2006, 10:41 PM) ...   Sep 15 2006, 06:00 AM
|- - dilo   QUOTE (JRehling @ Sep 15 2006, 04:41 AM) ...   Sep 15 2006, 09:22 AM
|- - ngunn   Nice diagram, but what is the object that appears ...   Sep 15 2006, 10:28 AM
|- - dilo   QUOTE (ngunn @ Sep 15 2006, 10:28 AM) Nic...   Sep 15 2006, 11:20 AM
|- - ljk4-1   What is really amazing is that - as far as 2000 OO...   Sep 15 2006, 01:44 PM
|- - ngunn   QUOTE (dilo @ Sep 15 2006, 12:20 PM) Good...   Sep 15 2006, 02:18 PM
|- - dilo   I have same suspect, ngunn... considerng also the ...   Sep 17 2006, 03:59 PM
- - Jyril   Based on various comments on blogs and such, I got...   Sep 14 2006, 11:21 PM
|- - dvandorn   QUOTE (Jyril @ Sep 14 2006, 06:21 PM) But...   Sep 15 2006, 02:05 AM
- - laurele   [font=Times New Roman][size=4] I strongly object ...   Sep 26 2006, 09:25 PM
|- - ugordan   QUOTE (laurele @ Sep 26 2006, 10:25 PM) t...   Sep 26 2006, 09:36 PM
|- - laurele   QUOTE (ugordan @ Sep 26 2006, 05:36 PM) I...   Sep 26 2006, 09:53 PM
|- - ugordan   QUOTE (laurele @ Sep 26 2006, 10:53 PM) I...   Sep 26 2006, 09:55 PM
|- - laurele   QUOTE (ugordan @ Sep 26 2006, 05:55 PM) T...   Sep 27 2006, 04:12 AM
|- - ugordan   The way I see it you're pushing for a petition...   Sep 27 2006, 06:58 AM
|- - laurele   I did not create this petition, and I am not pushi...   Sep 27 2006, 03:47 PM
||- - Kevin Heider   QUOTE (laurele @ Sep 27 2006, 08:47 AM) I...   Sep 27 2006, 07:09 PM
||- - laurele   [quote name='Kevin Heider' post='70120...   Sep 27 2006, 07:29 PM
||- - Kevin Heider   laurele: Why can't there be a subcategory of p...   Sep 27 2006, 10:19 PM
||- - laurele   If we find only one object (as large as Mars) in t...   Sep 29 2006, 11:19 PM
|- - Sedna   QUOTE (ugordan @ Sep 27 2006, 08:58 AM) T...   Sep 29 2006, 11:53 PM
|- - laurele   QUOTE (Sedna @ Sep 29 2006, 07:53 PM) Goo...   Sep 30 2006, 12:40 AM
|- - Sedna   QUOTE (laurele @ Sep 30 2006, 02:40 AM) I...   Sep 30 2006, 01:16 AM
|- - laurele   So do I, as a minor planet or such maybe... The au...   Sep 30 2006, 05:00 AM
|- - Sedna   QUOTE (laurele @ Sep 30 2006, 07:00 AM) T...   Oct 1 2006, 02:19 AM
|- - JRehling   QUOTE (Sedna @ Sep 30 2006, 07:19 PM) A s...   Oct 1 2006, 05:04 AM
- - Sedna   Teens and children here, Spain, are fortunately be...   Sep 26 2006, 09:37 PM
- - djellison   This thread is getting overly heated ( as it was o...   Oct 1 2006, 07:20 AM
- - Greg Hullender   Since Mike Brown, discoverer of the erstwhile ...   Oct 1 2006, 08:29 PM
|- - Alan Stern   QUOTE (Greg Hullender @ Oct 1 2006, 08:29...   Oct 1 2006, 08:57 PM
|- - Kevin Heider   QUOTE (Alan Stern @ Oct 1 2006, 01:57 PM)...   Oct 3 2006, 08:51 AM
- - Greg Hullender   Thanks Alan. That was great! (Except for the...   Oct 2 2006, 05:37 AM
|- - MahFL   Well I still think of Pluto as a planet, small, co...   Oct 2 2006, 11:12 AM
|- - Alan Stern   QUOTE (Greg Hullender @ Oct 2 2006, 05:37...   Oct 2 2006, 11:53 AM
|- - SFJCody   QUOTE (Alan Stern @ Oct 2 2006, 12:53 PM)...   Oct 2 2006, 02:09 PM
- - Greg Hullender   What is the boundary on the ability of a planet to...   Oct 2 2006, 02:23 PM
|- - JRehling   QUOTE (Greg Hullender @ Oct 2 2006, 07:23...   Oct 2 2006, 09:08 PM
|- - Kevin Heider   What would happen if we took Jupiter (as it is tod...   Oct 2 2006, 09:12 PM
|- - Bart   QUOTE (Kevin Heider @ Oct 2 2006, 02:12 P...   Oct 3 2006, 12:11 AM
- - Superstring   QUOTE Heider: Mars in orbit around Jupiter. Titan ...   Oct 3 2006, 02:17 PM
- - JRehling   To one and (almost) all: This planet definition i...   Oct 3 2006, 03:24 PM
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