Pluto Safe From Demotion
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From: Peter Langston <psl>
Date: Thu, 28 Jan 99 18:17:21 -0800
Subject: Pluto Safe From Demotion
[Background -- A number of items have appeared recently from Fun_Sources
mentioning the possibility that Pluto would be "downgraded" from a planet
to a TNO (TransNeptunian Object) or to an asteroid, and the practical
difficulties of such a change; e.g. if they're numbered in chronological
order by discovery, then do all the following numbers get bumped when
Pluto gets tagged with a low (early) number?
Forwarded-by: "Richard M. Koolish" <koolish@BBN.COM>
Forwarded-by: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
University of Kansas
Roger Martin, (785) 864-7239 email@example.com
Dann Hayes, (785) 864-8855 firstname.lastname@example.org
January 22, 1999
PLUTO SAFE FROM DEMOTION
LAWRENCE, Kan. -- The short national nightmare is coming to an end. The
solar system will continue to have nine planets.
"There is no plan to 'downgrade' or 'demote' Pluto," says Brian Marsden,
head of the International Astronomical Union's Minor Planet Center. "It will
stay as a planet."
Sometime early this year, it's likely Pluto will be designated a
"transneptunian object" -- but not lose its planetary status, as has lately
The designation, new for Pluto, already describes a group of 90 known bodies
on the outer fringes of the solar system.
"This is like giving it a social security number," Marsden said. "Humans
acquire names soon after birth. Later they get social security numbers. Does
having the latter demote them in some way? Of course not."
Controversy has swirled around the pint-sized planet for various reasons,
including its smallness and eccentric orbit. But the possibility of its
being demoted touched nerves.
Among the miffed was Patricia Fort Johnson, a former resident of Streator,
Ill. Pluto's discoverer, Clyde Tombaugh, was born near there.
Tombaugh attended high school in Burdett, Kan., and went to school at the
University of Kansas, in Lawrence, so the possible demotion rankled folks
in those towns, too. At KU, an observatory is named after Tombaugh.
Johnson recently wrote to Steve Shawl, KU professor of physics and
astronomy, about her distress.
"I would be sorely disappointed," she told Shawl, "if Pluto were to be
demoted from planet status. Where would be our truth?"
It was Shawl who put her in contact with Marsden, who responded with
assurance and the social security analogy.
All this amounts to quite a bit of fuss over an odd little ball. Pluto is
only about 1,450 miles across, about the distance between Kansas City and
Las Vegas. It's considerably smaller than Earth's moon, which is about 2,150
That's only one reason some people don't consider it a planet. Another is
that it breaks a trend in the solar system, says Bruce A. Twarog, KU
professor of physics and astronomy. While the inner planets, out to Mars,
are basically orbiting rocks, the outer ones are gigantic gas balls -- until
you get to Pluto, says Twarog.
If you drilled from the surface of Pluto toward its center, you'd be boring
through ice the first quarter of the way. It's nothing you'd want to put
into a margarita though, being frozen nitrogen, carbon monoxide and methane.
Currently, Shawl says, Pluto has a thin atmosphere. That's only because it's
as close to the sun as it ever gets, and the heat is changing some of the
ice into gas.
Pluto orbits the sun every 248 years, moving, unlike other planets, in a
big ellipse rather than a circle.
For about 20 of those 248 years, it's closer to the sun than Neptune, which
is ordinarily the eighth planet out from the sun, Shawl says. In fact, Pluto
has been the eighth planet since Jan. 21 ,1979, but becomes the ninth planet
again on Feb. 11 of this year -- and the pro-Pluto crowd can breathe a sigh
of relief that it will still be a planet on that date.
Despite Pluto's eccentricities, the debate about whether it's a planet is
"much ado about nothing," Shawl says.
David Tholen, a KU graduate now at the University of Hawaii, adds, "Debating
the dividing line between planet and minor planet, or asteroid, is like
debating the dividing line between city and town, river and stream."
"It's nothing that should send anybody out of orbit," Shawl says.
© 1999 Peter Langston