Interesting prediction! -- any guess at this point what term
might/should be adopted in the future for planets of the current
"dwarf" type?
Anyway, a curious conclusion of this dialogue is that I'm not sure if
I'd count as a "pro-planet" person or not. My position in a nutshell:
"Of course, Pluto or Ceres is a planet -- the question is, which kind?"
If the debate had been cast in those terms, I wonder if it might have
been less emotional and possibly more enlightening for the public.
Thank you for a most admirable and elegant solution regarding my concern, and one that seems totally in accord with common sense!
I was aware of the term "minor planet," but may have succumbed at least partly to the misunderstanding that Resolution 5A somehow preempts or excludes from "correct" discourse all usages not expressly appearing in it, including this term. Your response led me to realize that this resolution is more reasonably read as building upon rather than abrogating established astronomical concepts and usages, including the generic use of "planet" to include both "major planet" and "minor planet" -- and thus also "dwarf planet."
It was easy to confirm this generic usage of "planet" by checking the OED, some astronomy texts and dictionaries, and also a recent edition of a reference on the minor planets where someone involved with the IAU comments that a choice of name can be most satisfying when there is some salient connection between "the name" and "the planet."
Indeed, as you suggest, the lower limit in size for a minor planet (also now known in this lower range as a "Small Solar System Body") is around 10-100 meters, where anything smaller would be a "meteroid" or the like. And while I grew up on "asteroids" and "comets" as distinct categories, your remarks led me to read some persuasive arguments as to why, in today's understanding of our Solar System with its ice dwarves and the like, it makes sense to consider both as "minor planets."
Maybe I could repay you for your helpful pointer by writing an article on the "Is a dwarf planet a planet?" question, including some references illustrating the generic use of the term planet, and invite your feedback.
By the way, a question: Would the term "minnr planet" now serve as a kind of superset including both "dwarf planets" and "small Solar System bodies" as defined in Resolution 5A -- in other words, just about anything larger than a meteroid, and other than the eight major planets ("excluding satellites," of course)?
Please let me warmly agree that those of us who favor some revision of the adopted Resolution 5A should present our case in a calm, civil, and collegial matter, and recognize points of common agreement which might serve as a basis for broader consensus.
In fact, the only difference some of us have with Resolution 5A is that we would like recognition of the option to use "planet" in a generic sense to include both dynamically dominant or orbit-clearing major planets, and dwarf planets as defined in the resolution. In this view, what Giuseppe Piazzi actually did in 1801 was to discover a new kind of planet: Ceres, the first known dwarf or "belt" planet (the latter term borrowed from Gibor Basri) massive enough for self-gravitationally constrained near-sphericity, but sharing its orbit with a large population of other objects not under its gravitational influence or control.
Thus from this viewpoint, Resolution 5A correctly places both Ceres and Pluto in a category distinct from what I would call the eight major planets of our Solar System, and defines dynamical dominance or orbit clearing as the distinction between these two categories. The only revision that some of us favor for this Solar System taxonomy is that there should at least be a recognized alternative usage where the genus of "planethood" can embrace both major planets and dwarf planets.
Incidentally, while "dwarf planet" is fine, the synonymous "belt planet" focuses explicitly on the shared rather than essentially cleared orbital neighborhood of the body and might be especially apt in a planetary system where it happens that a belt planet in an outer region such as our Kuiper Belt or Oort Cloud is more massive than an inner major planet such as our Mercury.
Anyway, what I respectfully propose for discussion is that astronomy might take a leaf from the biological sciences and recognize two usages of the term "planet": a broad usage (_sensu lato_) including both major planets and dwarf planets; and a narrow or strict usage (_sensu stricto_) following IAU Resolution 5A and including only orbit-clearing bodies.
At the next IAU General Assembly in 2009, of course, such a diplomatic solution might well be proposed as part of a definition addressing extrasolar planets also. However, just to illustrate what I'm proposing, the "gentle tweak" to Resolution 5A could as simple as adding a new footnote 3 at the end of the definition of a dwarf planet:
In a broader or generic usage (_sensu lato_), the term "planet"
may include both planets and dwarf planets; and in such a usage,
planets in the stricter sense here defined (_sensu stricto_) may
also be referred to as "major planets."
Essentially this is a kind of "agreement to differ": the usage adopted in 5A remains the official standard, but the kind of minority viewpoint likely reflected by the defeated 5B gets recognition as an alternative usage. (Note that I much prefer the familiar "major planet" to "classical planet"!)
Please let me conclude by affirming again that in negotiating nuances of taste and semantics like these, civility and mutual respect among all the people involved, both astronomers and laypeople like myself, can smooth the process as we seek more elegantly to describe an exciting Solar System and universe.
Slashdot Mirror
Interesting prediction! -- any guess at this point what term might/should be adopted in the future for planets of the current "dwarf" type? Anyway, a curious conclusion of this dialogue is that I'm not sure if I'd count as a "pro-planet" person or not. My position in a nutshell: "Of course, Pluto or Ceres is a planet -- the question is, which kind?" If the debate had been cast in those terms, I wonder if it might have been less emotional and possibly more enlightening for the public.
Thank you for a most admirable and elegant solution regarding my
concern, and one that seems totally in accord with common sense!
I was aware of the term "minor planet," but may have succumbed at
least partly to the misunderstanding that Resolution 5A somehow
preempts or excludes from "correct" discourse all usages not expressly
appearing in it, including this term. Your response led me to realize
that this resolution is more reasonably read as building upon rather
than abrogating established astronomical concepts and usages,
including the generic use of "planet" to include both "major planet"
and "minor planet" -- and thus also "dwarf planet."
It was easy to confirm this generic usage of "planet" by checking the
OED, some astronomy texts and dictionaries, and also a recent edition
of a reference on the minor planets where someone involved with the
IAU comments that a choice of name can be most satisfying when there
is some salient connection between "the name" and "the planet."
Indeed, as you suggest, the lower limit in size for a minor planet
(also now known in this lower range as a "Small Solar System Body") is
around 10-100 meters, where anything smaller would be a "meteroid" or
the like. And while I grew up on "asteroids" and "comets" as distinct
categories, your remarks led me to read some persuasive arguments as
to why, in today's understanding of our Solar System with its ice
dwarves and the like, it makes sense to consider both as "minor
planets."
Maybe I could repay you for your helpful pointer by writing an article
on the "Is a dwarf planet a planet?" question, including some
references illustrating the generic use of the term planet, and invite
your feedback.
By the way, a question: Would the term "minnr planet" now serve as a
kind of superset including both "dwarf planets" and "small Solar
System bodies" as defined in Resolution 5A -- in other words, just
about anything larger than a meteroid, and other than the eight major
planets ("excluding satellites," of course)?
Most appreciatively, with many thanks,
Margo Schulter
Please let me warmly agree that those of us who favor some revision of
the adopted Resolution 5A should present our case in a calm, civil, and
collegial matter, and recognize points of common agreement which might
serve as a basis for broader consensus.
In fact, the only difference some of us have with Resolution 5A is that
we would like recognition of the option to use "planet" in a generic
sense to include both dynamically dominant or orbit-clearing major
planets, and dwarf planets as defined in the resolution. In this view,
what Giuseppe Piazzi actually did in 1801 was to discover a new kind of
planet: Ceres, the first known dwarf or "belt" planet (the latter term
borrowed from Gibor Basri) massive enough for self-gravitationally
constrained near-sphericity, but sharing its orbit with a large
population of other objects not under its gravitational influence or
control.
Thus from this viewpoint, Resolution 5A correctly places both Ceres and
Pluto in a category distinct from what I would call the eight major
planets of our Solar System, and defines dynamical dominance or orbit
clearing as the distinction between these two categories. The only
revision that some of us favor for this Solar System taxonomy is that
there should at least be a recognized alternative usage where the genus
of "planethood" can embrace both major planets and dwarf planets.
Incidentally, while "dwarf planet" is fine, the synonymous "belt
planet" focuses explicitly on the shared rather than essentially
cleared orbital neighborhood of the body and might be especially apt in
a planetary system where it happens that a belt planet in an outer
region such as our Kuiper Belt or Oort Cloud is more massive than an
inner major planet such as our Mercury.
Anyway, what I respectfully propose for discussion is that astronomy
might take a leaf from the biological sciences and recognize two usages
of the term "planet": a broad usage (_sensu lato_) including both major
planets and dwarf planets; and a narrow or strict usage (_sensu stricto_)
following IAU Resolution 5A and including only orbit-clearing bodies.
At the next IAU General Assembly in 2009, of course, such a diplomatic
solution might well be proposed as part of a definition addressing
extrasolar planets also. However, just to illustrate what I'm
proposing, the "gentle tweak" to Resolution 5A could as simple as
adding a new footnote 3 at the end of the definition of a dwarf planet:
In a broader or generic usage (_sensu lato_), the term "planet"
may include both planets and dwarf planets; and in such a usage,
planets in the stricter sense here defined (_sensu stricto_) may
also be referred to as "major planets."
Essentially this is a kind of "agreement to differ": the usage adopted
in 5A remains the official standard, but the kind of minority viewpoint
likely reflected by the defeated 5B gets recognition as an alternative
usage. (Note that I much prefer the familiar "major planet" to
"classical planet"!)
Please let me conclude by affirming again that in negotiating nuances
of taste and semantics like these, civility and mutual respect among
all the people involved, both astronomers and laypeople like myself,
can smooth the process as we seek more elegantly to describe an
exciting Solar System and universe.
Margo Schulter
mschulter at calweb dot com