Nomenclature Wars & Splitting Headaches
MexicoDoug at aol.com
MexicoDoug at aol.com
Fri Aug 15 00:21:04 EDT 2003
Hello Lepsters (don't miss the article below of how another science tackles
the name issue),
With Mars, Moon, and Meteors falling from Perseus this has been an astronomy
week, with a capital "M". Scientific observation and contribution truly are
reasons to live. Perhaps the Full moon alignment with Mars has produced the
additional gravitation potential to affect the power outage that the world seems
to be so bent out of shape over. Truly enjoy it if you are there, as the
skies out to be wonderful for observation with all the repugnant light pollution
knocked out (with all due respect to essential uses of energy).
With respect to the Lep abovementioned controversies, and the vocal
taxonomists & splitters and lumpers among us, I just wanted to propose that the
discussion not be so Lep-centered, but more abstract in nature. A different
viewpoint that is not for the birds might actually help somewhat. At risk of being
burned on a stake, we don't live in a Lep-centered Solar System, and clearly,
Leps nomenclature ought to be a cake-walk in the park compared to the parrallel
splitting and lumping of stellar proportions (and probably galactic as well)
going on now that it is clear that Pluto is a Kuiper Belt Object and not a
planet, and that "asteroids" lumps improperly, and splitting will soon result in
as many objects in the Solar System as butterfly species in Scott, not to
mention that a comet is not always a comet, but sometimes a cosmic simoon which
covers more than Europe. Oh, and a Moon is not always a Moon either. Except for
those who decide to call it one. He he je. That reminds me that the Moon is
really a planet and earth rotates around it, too in a two planet mob. Too
bad there are no Lep cubewanos that I am aware of. At least some astronomers
still have salvaged their sense of humor.
Happy butterflying, and clear skies.
Doug Dawn
Monterrey, Mexico
Crazy Names: The Solar System's Nomenclature Wars
By <A HREF="mailto:rbritt at hq.space.com">Robert Roy Britt</A>
Senior Science Writer
posted: 07:09 am ET
12 August 2003
You might be surprised to learn that the outskirts of the solar system are
loaded with Plutinos, Centaurs, cubewanos and EKOs. Astronomers didn't even know
this a decade ago. In fact until 1992 they hadn't even invented three of the
terms.
Now it seems they don't have enough of these crazy names.
During the past decade, hundreds of objects have been discovered in a
bewildering range of locations and orbital configurations beyond Jupiter. During that
same time, astronomers have invented a puzzling set of designations -- some
straightforward, some creative, some downright amusing -- to describe their
findings.
The result is a charming lexicon that unfortunately does not properly des
cribe what's out there, according to some experts. More names are needed, one
group of astronomers argues.
Fix it
Jonathan Horner, an Oxford University researcher who leads the push for an
expanded space rock vocabulary, calls the present system "not very
enlightening." His approach claims to allow for a better understanding of the history and
fate of these wanderers of the way-out.
The new scheme would be tacked onto -- or rather under -- the existing one,
Horner explained in an e-mail interview.
Existing "umbrella terms" like <A HREF="http://www.space.com/scienceastronomy/comets_eroded_030807.html">comet</A>, asteroid and even the enchanting
cubewano (etymology forthcoming) would be retained. Objects would be further defined
based on how they are gravitationally glued to certain planets. As an
example, a rock under the spell of Saturn and Uranus and traveling a certain path
might be labeled SU IV.
It is not known if the new classification system will catch on. But it is
clear that it represents just the latest chapter in what one researcher calls the
outer solar system's "nomenclature wars."
Since the early 1800s, astronomers have known about asteroids, which are
mostly confined to a belt between Mars and Jupiter. Ah, were it so simple anymore!
KBO, EKO or TNO?
In the 1940s, Irish economist and astronomer Kenneth Edgeworth predicted
there might be a more distant belt of objects orbiting the Sun beyond Neptune.
Dutch-American astronomer Gerard Kuiper made a similar prediction in the early
1950s (apparently without knowing about Edgeworth's writings).
Kuiper's prediction was more widely recalled when, in 1992, the first of
these distant space rocks was discovered. Most astronomers began using the terms
Kuiper Belt and Kuiper Belt Object (KBO), but soon Edgeworth was remembered and
controversy arose.
"One compromise was to call it the Edgeworth-Kuiper Belt (EKB)," explains
Joel Parker of the Southwest Research Institute (SwRI). Parker maintains an
electronic newsletter called Distant EKOs, for Edgeworth-Kuiper Objects, the term
of preference for those who support the EKB alternative.
Adding to the controversy, some scientists pointed out that even earlier
predictions of the faraway objects were made by other researchers in the 1930s.
None of their names eked into the peculiar phraseology of the outer solar
system, but a minor political correctness movement ensued.
"One suggestion was to call them by the non-partisan and more descriptive
name 'Trans-Neptunian Objects' (TNOs)," Parker told SPACE.com.
The terms KBO and TNO are interchangeable and used with about equal
frequency, he said, and EKO is employed "much less so, and will probably disappear from
common use soon -- leaving the title of the newsletter as a mysterious relic
of past nomenclature wars."
Plutinos and other odd names
We're just getting started here.
As more types of objects were discovered, astronomers noticed distinctions
between them having to do with where and how they roam. While many space rocks
circle the Sun relatively unencumbered, some are gravitationally linked to
planets.
Hence terms like Plutino, cubewano and Centaur.
As if merely to confuse things further, a Plutino has a weighty affinity for
Neptune, not for that other planet you might have suspected. In science terms,
a Plutino is in a 2:3 mean motion resonance with Neptune.
"This means the object goes around the Sun twice in the amount of time it
takes Neptune to go three times around," Parker explains. "So, the term refers to
a kind of orbit, not anything about the physical properties of the objects."
Pluto is in a 2:3 resonance with Neptune, too, and since it was the first of
this sort of character, the others came to be called Plutinos, Parker said.
I should point out here that Pluto itself is considered a KBO, and not a
planet, by many astronomers. Further, a handful of KBOs are <A HREF="http://www.space.com/scienceastronomy/quaoar_discovery_021007.html">nearly as large as
Pluto</A>. One astronomer recently proposed calling anything this big a planet. If
that were adopted, the solar system's total would <A HREF="http://www.space.com/scienceastronomy/planet_denitions_030227.html">jump instantly</A> from 9 to 12.
The amusing cubewano
Back to our head-spinning array of terms. Objects near Plutinos that are not
attracted into resonances with Neptune are called cubewanos. These make up the
"classical" Kuiper Belt, a relatively thin region of space that corresponds
to the same plane in which most of the planets orbit, Parker explained.
The origin of the word "cubewano" is perhaps the most extreme example of
nomenclative amusement among astronomers.
The first KBO found was initially designated 1992 QB1, Parker explains. It’s
a name that denotes the year, month and order of discovery and is typical for
newfound objects whose orbits are not pinned down. It was later learned that
1992 QB1 was a "main belt" KBO, not a Plutino, and so astronomers just began
sounding out "QB1" and a new term was born.
Space rock aficionados might be thinking by now of a more familiar acronym,
the dread NEO. This necessarily draws our discussion inward.
Inner headaches
Near Earth Objects (<A HREF="http://www.space.com/scienceastronomy/impact_debate_part1_030211.html">NEOs</A>) are asteroids and comets that zoom through space in
the general vicinity of Earth's orbit and therefore bear watching in case one
might hit us some day. Since almost all NEOs are asteroids, some scientists
prefer to call them NEAs. The most threatening of these are termed Potentially
Hazardous Asteroids, or PHAs.
Oh, and did I mention Trojans? These rocks don't reside in the main asteroid
belt, but instead travel in lockstep with Jupiter, orbiting the Sun either
ahead of or behind the giant planet. And then there is the recently discovered "<A HREF="http://www.space.com/scienceastronomy/earth_asteroid_021021.html">
quasi-satellite</A>" of Earth, a semi-captured asteroid that is like a Trojan but
not quite meriting the title, and decidedly not a moon.
Scientists who hunt for and classify space rocks of the inner solar system
have their own looming problem. The tally of known moons has soared well above
100 and the typical diameters of new finds have dropped to just a mile or two.
Some researchers are wondering if the term "moon" might <A HREF="http://www.space.com/scienceastronomy/moon_definition_040103.html">need a makeover</A> when
orbiting satellites no bigger than an SUV are found.
But this story is not about any of these pesky boulders of the inner solar
system, so let's get back on track.
Not all very distant objects (would it be too simple to just call everything
beyond the ISS a VDO?) stick to the main orbital plane of the solar system in
nice, circular orbits. So, you guessed it, more terms were developed.
Scattered Disk Objects (SDOs) take paths that are highly inclined to the main plane or
are very eccentric, meaning they might come inside Neptune's orbit and then
wing outward up to 10 times that distance from the Sun.
Finally, beyond all the objects discussed so far is the Oort Cloud, a sphere
of <A HREF="http://www.space.com/scienceastronomy/comets_eroded_030807.html">comet-like objects</A> that envelops the entire solar system and extends up to
half the way to the next known star.
You would be hard-pressed to find the term OCO anywhere, but there is at
least one reference (in a scientific paper last year) using this acronym along
with the term Oort Cloud Object. Most often scientists call these most distant
members of the solar system "Oort Cloud comets," however, and do not employ an
acronym.
Centaurs and change
I promised earlier to tell you about Centaurs. They are truly odd, and they
are at the heart of the movement for a new classification system.
Astronomers can't decide whether to think of Centaurs as comets or
asteroid-like KBOs. Many of these strange bodies are more than 62 miles wide (100
kilometers), which is way bigger than a comet is supposed to be. Yet they're known
to generate clouds of gas and dust characteristic of a comet.
Importantly, Centaurs carve non-circular paths around the Sun and are
typically affected by the gravity of two planets. When closest to the Sun, a
Centaur's movement might be directed by Jupiter or Saturn. Farther out, it could fall
under the influence of either Uranus or Neptune.
In addition, Centaurs can be divided into four types based on how much their
paths are tilted with respect to the main orbital plane of the solar system,
Horner's team says. So their proposal would generate labels like SN III and SU
IV, with the letters standing for planets and the Roman numerals representing
orbital inclination. The notation could be extended to cover objects beyond
Centaurs, but that aspect hasn't been worked out yet.
A paper detailing the proposed classification system will be published in the
Aug. 21 issue of the Monthly Notices of the Royal Astronomical Society.
Armagh Observatory astronomers Mark Bailey and David Asher, along with Wyn Evans of
Oxford and Cambridge universities, contributed to its creation.
No existing terms need be discontinued. "I'm quite attached to them myself,"
Horner said.
SwRI's Joel Parker, who was not involved in developing the new plan, says
classifying objects by type of orbit is useful because "theories of the formation
of the outer solar system make predictions about how many objects are in each
type of orbit and explain how they get there."
Whether or not any of this gains widespread use depends on how useful other
astronomers find it, Horner's team figures.
What's Earth got to do with this?
Since the scheme would help astronomers trace the histories of objects that
share similar orbits, it would also help them predict where those things might
end up.
"We hope that we have perhaps cast a net of order over what up to now has
been a rather chaotic field," Bailey says, aware that chaos reigns not just among
astronomers but in the outer solar system, too.
Which leads us to what is perhaps the most pragmatic motivation for putting
more ink behind the names of newfound objects.
Bailey points out that some of these very distant and very large hunks of
stone and ice -- be they comets or Centaurs or whatever -- will eventually end up
being booted to the inner solar system.
"The enormous amount of dust that would come off such an object as it
approached the Sun would be an environmental hazard for Earth," Bailey said.
Worse, Earth could get directly in the way, in which case the whole scheme
might be blasted into oblivion. But at least we'd have had a better chance to
see it coming.
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