1 Year Without Pluto - & 12 reasons to reinstate it!

Mungascr · #1 (**permalink**) 25-August-2007, 07:35 AM

August 24th marks the first anniversary of the demotion of Pluto from being a full planet; a decision taken (wrongly I'd say) by the Prague IAU meeting on this date last year. (Surprised Phil Plait hasn't put something up about that on the Feed Blitz / main blog thingy actually! )

To commemorate the occasion, here's my list of 12 reasons (1 per month without Pluto as a full planet) why I think the IAU decision was wrong :

_* 12 REASONS WHY PLUTO _IS_ A PLANET : *__

1) The orbital clearing condition which is the reason for eliminating Pluto is fatally flawed because it is itself too hard to define – what is meant by “cleared” & how far from the planet must the orbit be "cleared"? Strictly speaking this eliminates any object in our solar system as all planets have objects – comets and asteroids crossing their orbits, Jupiter has Trojan asteroids, Neptune has Pluto crossing its orbit, Earth has numerous near-earth asteroids such as Eros and so forth. A consistent application of this criterion would exclude all the planets of our solar system!

2) A 'reductio ad absurdum' approach reveals that this criterion fails because it leads to absurd results ruling out objects we’d clearly consider planets based on their location – a Jupiter or Earth-type planet hypothetically located in the Oort cloud would be excluded yet we'd clearly still call it a planet otherwise! Why then draw the line at smaller objects that would otherwise fit the planetary description ie. rounded by their own gravity and directly orbiting the Sun? (Or their common centre of gravity for "double planets.")

3) In relation to forming planetary systems including historically our own, planetary orbits cross and interact in unpredictable ways. By the IAU’s "orbital clearance" criterion, these objects - even ones Jupiter sized and above – are NOT strictly planets because their orbits are not yet cleared – again failing the 'reductio ad absurdum' test. Eg : The earth before it was hit by the Mars-sized body that became our Moon would NOT have been termed a "planet" because it had that Mars-sized object in its orbital path.

4) From point 3 above, we see that by IAU definitions planets cannot collide because their neighbourhood then isn’t clear – nor can they exist as binaries or “double planets” by the same logic. This appears contrary to common-sense and consistency. It also has potential for creating trouble with exoplanets given the so-far hypothetical but quite probable possibility that some extrasolar planets may exist in this form – even potentially twin Neptunes or Jupiters. Given that some would describe the Earth-Moon system as well as the Pluto-Charon one as such a ‘double planet’ then a strict definition of the IAU rule may rule our Earth out of planetary status again clearly a ridiculous proposition!

5) Inconsistency and inapplicability in regard to exoplanets – the IAU definition excluded planets of other stars. Yet surely planets orbiting other suns are no less planets for not orbiting our star! Even more tellingly, at least one of the Pulsar planets, PSR B 1257+12 e is tiny – smaller than our Moon and smaller than Pluto raising a glaring inconsistency. Given PSR1257+12 e is counted as an exoplanet then Pluto, equally, should equally count as a planet for the sake of consistency.

6) The “dwarf planet-dwarf” star analogy – just as dwarf stars are still stars so surely are dwarf planets still planets. Extrapolating the “dwarf planets don’t count” line to stellar astronomy would imply the Sun is not a proper star nor are 99 % of all stars – those 90% on the main-sequence and the 10 % of “stellar corpses” such as white dwarfs and neutron stars. Moreover, as with stars, the smaller the object's size the greater its numbers! Therefore calling a planet “dwarf” should NOT rule it out of being considered a proper planet.

7) “Classical” problems with the “classical” planets term : the IAU defined “classical”; planets are restricted to our Earth’s solar system and it is hard to see how they apply to exoplanets or how the term can work usefully as a scientific description. Apart from differing immensely – Earth and Pluto are arguably far more similar worlds than Earth and Jupiter or Mercury or Neptune – they also clash with a previous understanding arguably much more apt of classical planets being those visible to the “classical” age peoples – the five original bright wanderers – Mercury, Venus, Mars, Jupiter, & Saturn. If that ‘classical’ term is retained, it seems best used in this sense as a historical and descriptive sense.

8) Sentimental, cultural and historical reasons – noting Pluto’s long-established and culturally scientific place as a recognised planet from its discovery in 1930 until its demotion in 2006. This also covers the slight to Clyde Tombaugh’s memory, widow and family plus the perceived political aspect of stripping from planetary status the sole planet discovered by an American.

9) The undemocratic manner in which the IAU ruling was made. For instance, of the 10,000 IAU members only 2,500 attended the Prague meeting that demoted Pluto and rejected the other planetary candidates, Eris, Charon and Ceres from planetary status. Furthermore, of those 2,500 only the merest handful – just 424 actually got to vote making therefore a very unrepresentative decision. Among those to excluded from voting and arguing their case in that last minute meeting were some highly relevant and articulate people - notably Pluto expert Alan S. Stern, head of the New Horizons mission. Stern's summary of the IAU judgement was blunt : “ ... idiotic. I have nothing but ridicule for this decision.” (Alan Stern, P.28, ‘Astronomy Now’ magazine, October, 2006.)

10) The decision to demote Pluto has had a generally negative reception from the general public and on public perceptions of astronomers.

11) The first proposed IAU definition of 'planet' (that would have included Pluto, Eris and Ceres) was much better in terms of logical consistency and general application as well as being more easily explained, understand and applied - ie. two main criteria for planets are that they are objects circling a star directly which are not themselves stars or brown dwarfs and are rounded by their own gravity.

12) Pluto is a complex world with the key aspects of planets - it dominates its own satellite system of three moons (Charon, Hydra & Nix), has its own atmosphere, has a complex geology and weather system. (Of nitrogen ice subliming into atmosphere near perihelion then frosting, snowing or raining back later based on HST images and theory.) Some theorists even think Pluto has rings like Saturn -albeit obviously nowhere near as bright! Pluto meets all the criteria for planethood with the sole exception of the problematic and, I believe, absurd "orbital clearance" criterion.

***

Hopefully, there won't be too many more years that pass before the IAU's decision is reversed and Pluto re-instated as a planet along with Eris and Ceres!

Mungascr · #2 (**permalink**) 25-August-2007, 08:19 AM

Tried to edit but the wretched diabolical piece of excrement of a computer didn't seem to do so despite repeated attempts! It just kept thesave cyclingforwever without actually doing anything ..

What can't we even edit here anymore? Or is it just my useless pile of effluent of a machine? Arrgghh! Yegods this is frustrating ...!

A-n-y-w-a-y, trying now to cut & paste in the corrected draft - if I can I intend to replace the material above with this material below :

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Done! Finally got it to work thanks to the Go Advanced suggestion and someone kindly posting the link to that 'Why editing is so slow?' thread! Thanks again!
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What computers really need is a "Just effen WORK!" button which when pressed makes the blasted machine just effen WORK!

parallaxicality · #3 (**permalink**) 25-August-2007, 08:45 AM

1. Steven Soter has a perfectly good quantifiable definition for orbital clearing: if an object is more massive than the combined mass of all objects which intersect its orbit at least once and whose orbital periods differ from it's own by less than an order of magnitude, then it can be said to dominate its orbit.

2. If the Oort cloud had an object the size of Jupiter in it, then it's doubtful the Oort cloud would even exist, since it was created (according to current models) by comets in the inner solar system being thrown out into inclined orbits by the motions of Jupiter.

3. Such objects are already called protoplanets. It makes perfect sense to retain that word

4. Double planets need not be considered individually, but as a single unit that has collectively cleared its neighborhood. The Earth-Moon system is already considered this way, and it is essentially a double planet.

5. The IAU has its own separate working definition for exoplanets, one that has its own set of problems, but which is not related to orbital clearing

6. "Dwarf planet" was a sop to the pro-Plutonians. Most dynamicists didn't want it.

7. Pluto has more in common with Halley's Comet than it does with Earth. Jupiter has more in common with Saturn than it does with Neptune, and Mercury has more in common with the Moon than it does with Mars. Where do you draw the line? As per Classical planets, the old classical planets are also called the naked eye planets. Plus, inferior and superior planets mean both a planet inside and outside the asteroid belt (in heliocentrism) and a planet above and below the orbit of the Sun (in geocentrism) and those two definitions don't really conflict.

8. If science had followed that argument, then we would be teaching creationism in biology classes because people are sentimentally attatched to their religious beliefs.

9. What else could have been done? Alan Stern complains, but he wasn't there. If he truly cared, he should have shown up and participated in the vote. That's like people who don't vote in elections complaining that we always get the same people elected.

10. A lot of science, genetics, evolution, nuclear physics, space exploration, is negatively perceived by the public. Science isn't about PR. It's about reality.

11. The initial definition was a mess; attempting to incorporate Charon and use of the term Pluton were so roundly despised they were unanimously voted down.

12. Pluto also fits many descriptions of a comet. It's atmosphere is a sublimation of its surface by radiation from the Sun. Its orbit is highly elliptical and inclined, and it is largely composed of ice. Many asteroids have satellites, and countless KBOs also have complex satellite systems. Are they planets too?

Mungascr · #4 (**permalink**) 25-August-2007, 10:23 AM

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