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pluto = minor planet
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From: Frank Spera <spera@xxxxxxxxxxxxx>
FOLKS:
i would not worry too much about these semantic games.
pluto has been re classified as a MINOR PLANET like about 8000 other
recoverable objects of the Main Belt asteroids. Pluto is simply one of
the larger Kuiper Belt objects, some of which are large enough to be
classified as MINOR PLANETS.
fs
*Pluto gets the boot
**Pluto no longer a planet, say astronomers
*Thursday, August 24, 2006; Posted: 5:24 p.m. EDT (21:24 GMT)
*PRAGUE, Czech Republic (AP) -- Leading astronomers declared Thursday
that Pluto is no longer a planet under historic new guidelines that
downsize the solar system from nine planets to eight.
*After a tumultuous week of clashing over the essence of the cosmos, the
International Astronomical Union stripped Pluto of the planetary status
it has held since its discovery in 1930. The new definition of what is
-- and isn't -- a planet fills a centuries-old black hole for scientists
who have labored since Copernicus without one.
Although astronomers applauded after the vote, Jocelyn Bell Burnell -- a
specialist in neutron stars from Northern Ireland who oversaw the
proceedings -- urged those who might be "quite disappointed" to look on
the bright side.
"It could be argued that we are creating an umbrella called 'planet'
under which the dwarf planets exist," she said, drawing laughter by
waving a stuffed Pluto of Walt Disney fame beneath a real umbrella.
The decision by the prestigious international group spells out the basic
tests that celestial objects will have to meet before they can be
considered for admission to the elite cosmic club.
For now, membership will be restricted to the eight "classical" planets
in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn,
Uranus and Neptune.
Much-maligned Pluto doesn't make the grade under the new rules for a
planet: "a celestial body that is in orbit around the sun, has
sufficient mass for its self-gravity to overcome rigid body forces so
that it assumes a ... nearly round shape, and has cleared the
neighborhood around its orbit."
Pluto is automatically disqualified because its oblong orbit overlaps
with Neptune's.
Instead, it will be reclassified in a new category of "dwarf planets,"
similar to what long have been termed "minor planets." The definition
also lays out a third class of lesser objects that orbit the sun --
"small solar system bodies," a term that will apply to numerous
asteroids, comets and other natural satellites.
It was unclear how Pluto's demotion might affect the mission of NASA's
New Horizons spacecraft, which earlier this year began a 91/2-year
journey to the oddball object to unearth more of its secrets.
The decision at a conference of 2,500 astronomers from 75 countries was
a dramatic shift from just a week ago, when the group's leaders floated
a proposal that would have reaffirmed Pluto's planetary status and made
planets of its largest moon and two other objects. (_Watch why some
think planet size doesn't matter -- 3:39_)
That plan proved highly unpopular, splitting astronomers into factions
and triggering days of sometimes combative debate that led to Pluto's
undoing.
Now, two of the objects that at one point were cruising toward possible
full-fledged planethood will join Pluto as dwarfs: the asteroid Ceres,
which was a planet in the 1800s before it got demoted, and 2003 UB313,
an icy object slightly larger than Pluto whose discoverer, Michael Brown
of the California Institute of Technology, has nicknamed "Xena."
Charon, the largest of Pluto's three moons, is no longer under
consideration for any special designation.
Brown was pleased by the decision. He had argued that Pluto and similar
bodies didn't deserve planet status, saying that would "take the magic
out of the solar system."
"UB313 is the largest dwarf planet. That's kind of cool," he said.
//
--
They made a wasteland and called it peace.
Tacitus (55-115 AD)
Frank J. Spera
Department of Earth Science
University of California
Santa Barbara, California 93106
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