| Proposed Amendment to the August 2006 IAU Definition of "Planet"
Text below original August 30, 2006 Updated September 8
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In Brief: current IAU sub-defintion
"and (c) has cleared the neighbourhood around its orbit." proposed amended sub-definition
"and (c) dominates the neighborhood around its orbit clearing it of comparable objects." Brian Fenerty In Full: To all concerned,
I am an amateur astronomer in Calgary, Canada, a member of the Royal Astronomical Society of Canada, and a informal-presenter of various astronomy topics for public-telescope-viewing nights at our large city's science centre. The following are my personal views based on experience with editing, effective amendments, and teaching/presentation in various fields.
One of several vital aspects which the adults and children at these informal astronomy presentations pick up is, I hope, the value of rigor in science. Especially the children I hope are inspired to appreciated that sometimes precision and method, or whatever words they or we use for rigor, have a valuable role in exploring and finding out about one's place in this marvelous universe at a deep and vast scale.
However, the voted-in planet sub-definition (c) creates a serious problem for any in-depth public presentation or discussions about planets, I submit. Whereas parts (a) and (b) appear essentially complete, unambiguous and I would argue, rigorous, on the other hand part (c) creates a jarring discontinuity, too easily taken as the opposite: incomplete and ambiguous. Well might some in my audiences ask, "What does clearing mean?" "Doesn't Jupiter still have asteroids ahead and behind it -- don't they have to be cleared?" "What about Neptune clearing Pluto?" Maybe even "Does clearing have to be above and below the orbit? How much above and below? So, what about highly inclined orbits?" And "Couldn't they have said a few words on what they meant by 'cleared'?" some astute young potential-scientist will ask -- or should ask! What "clearing" means may be intuitive for some people, and surely is clear to the drafters or supporters of part (c) -- but for many others, "clear" may be far from clear! The post-vote debate by various professionals strongly suggests that the lack of rigor in part (c) of the definition bothers not just laymen.
Since I always look for positive angles in giving public presentations, for this autumn I plan to interpret or suggest the existing minimal wording of (c) to more fully imply that a planet _dominates_ its orbital neighborhood and thus has cleared away any otherwise comparable objects, since I trust (although perhaps wrongly?) that that was the actual principle behind the drafting of part (c). -
I write this personally not so much about whether or not a beloved-by-many solar system wanderer retains its status - I can see both sides of the issue and diverse technicalities.
Rather, in writing about the appearance of incompleteness or ambiguity or vagueness of part (c), and about this appearance's undermining effect on the encouragement of public appreciation of science and its valuable methods -- especially on the impression, subconscious or conscious on young, potential scientists -- I wish to submit a suggestion which you or others may find useful -- or much more likely, are already considering some variation thereof, being the following minor word amendment:
replace ""and (c) has cleared the neighbourhood around its orbit."
with "and (c) dominates the neighborhood around its orbit clearing it of comparable objects."
If "comparable" and "neighbourhood" in the above example wording need additional clarification, rather than extending (c) yet further, I personally favor a brief footnote as better, such as the brief statement "'comparable' and 'neighbourhood' will be found detailed elsewhere." This leaves formulation of what measurably constitutes "comparable" and "neighbourhood" to separate IAU determination, thus keeping the amendment itself (and its footnote) quicker to deliberate upon, shorter and diverging little from the original thus hopefully readily acceptable by an amending body.
If how the amendment with footnote can be applied is examined closely and with open minds, it can be seen as useful to both sides of this issue and maybe resolve considerable dispute. The amendment proposed above should not be construed as automatic support for the "demotion of Pluto", appearing to be merely a clarification of the demoting definition. Rather, my suggestion is that IF a significant alternative to the IAU resolution cannot clearly prevail at this time in the astronomy community, then this proposed wording may provide a compromise both palatable and healing, so to speak. Neither side of the issue needs to see this as backing down: the proposed amendment not only builds directly and briefly on the voted resolution's wording, but the separable determination of what "comparable" and "neighbourhood" actually would be measurably, even allows the possibility e.g. for Pluto to be "reinstated" -- provided done rigorously.
If you find this approach useful, please consider forwarding this page's web address to others (scientists, amateur astronomers, teachers, publishers of texts, et al) or you may copy the TEXT of this page IN FULL and send in its entirety unchanged as an eMail, for others to consider as well. Much appreciated.
http://www.telusplanet.net/public/fenertyb/amendiau.htm
Brian Fenerty
Calgary, Canada
contact - text only please - no attachments accepted by my filters:
fenertyb (at) telusplanet.net
Reference: IAU resolution 5A, scroll down to, on wep page
http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html
illustration top
Illustration:
(c) 2006 B Fenerty
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