[meteorite-list] John Hopkins Astronomers React to Pluto's Planetary 'Demotion'

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Aug 24 15:39:17 2006
Message-ID: <200608241936.MAA19782_at_zagami.jpl.nasa.gov>

THE JOHNS HOPKINS UNIVERSITY
OFFICE OF NEWS AND INFORMATION
901 S. Bond Street, Suite 540
Baltimore, MD 21231
Phone: (443) 287-9960 / Fax: (443) 287-9920

August 24, 2006
FOR IMMEDIATE RELEASE
CONTACT: Dennis O'Shea, dro_at_jhu.edu,
  or Phil Sneiderman, prs_at_jhu.edu
(443) 287-9960

JOHNS HOPKINS ASTRONOMERS REACT TO PLUTO'S PLANETARY 'DEMOTION'

Several Johns Hopkins University astronomers described a decision Thursday
to strip Pluto of its planetary status as a "muddled" ruling that is
unlikely to settle ongoing debates over how to define a planet and whether
the term should apply to Pluto. In an informal poll, only one astronomer
was pleased to hear about Pluto's new status.

Their reactions came after a vote by the International Astronomical Union,
meeting in Prague, that defined a planet as "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." Because Pluto does not meet
the last criterion, the IAU demoted it to "dwarf planet" status.

The decision leaves the solar system with only eight planets. Since its
discovery in 1930, Pluto has been considered the system's ninth planet.

Following are some comments about the IAU decision from astronomers at the
Henry A. Rowland Department of Physics and Astronomy at the Johns Hopkins
University's Krieger School of Arts and Sciences and The Johns Hopkins
University Applied Physics Laboratory. The Applied Physics Laboratory is
managing the mission of NASA's New Horizons spacecraft, which was launched
earlier this year on 9 1/2-year journey to explore the distant region that
includes Pluto.

* Andrew Cheng, Johns Hopkins University Applied Physics Laboratory:
"I think the IAU vote is a muddled compromise that will not settle the
question of 'What is a planet?' Pluto is not a 'planet' according to
resolution 1, but it is a 'dwarf planet' by resolution 2. So is it a
'planet?' I thought so before and still think so now -- but those who did
not think so before can now point to the IAU definition and say that Pluto
is really not a planet but a sort of second-class citizen.
"Actually, that is the same situation that has prevailed with Ceres, other
asteroids, and comets for many years (centuries in the case of some of
these objects). Those objects were known as minor planets before, but now a
few of the minor planets have been promoted to 'dwarf planets.'

"So I suppose I should be happy that Pluto wasn't demoted all the way into
the minor planet category."

* Harold (Hal) Weaver, Johns Hopkins University Applied Physics Laboratory
and New Horizons project scientist:
"I don't expect the hoopla over the demotion of Pluto from the realm of
'classical planets' to have any effect on the conduct of the New Horizons
mission. The scientific investigation of Pluto remains an important
component of our effort to understand the processes that shaped the outer
solar system, even if some of the objects in that region defy our efforts
to categorize them. The New Horizons mission remains as viable as ever
because it will provide the initial reconnaissance of one of the solar
system's newly discovered frontiers.
        
"Regarding the resolution itself, I'm with Andy Cheng in concluding that
the situation is still somewhat muddled. What exactly is meant by a planet
'clearing its neighborhood?' Since many 'plutinos' - (including Pluto) -
cross Neptune's orbit, I'd say Neptune's neighborhood still needs some
clearing! It just seems a bit risky to me to base a definition on a
theoretical construct ('dynamically cleared regions') that's only
approximate at best and may change significantly as our understanding of
planet formation evolves over time.
        
"I further note that there have been particularly large swings in the
theories of outer solar system dynamical evolution during the past decade.
What was 'conventional wisdom' five years ago has been replaced with the
latest fad, and I don't expect that situation to change any time soon."
        
* Karl Glazebrook, professor in the Department of Physics and Astronomy:
"What is meant by 'clearing its orbit?' How does this relate to having an
orbit overlapping Neptune? Clearly Neptune has not cleared its orbit.

"They should have gone with something clean like a size criterion. Seems to
me like a muddled compromise which will just cause more problems (what
about some of the weird orbits extra-solar planets have?) and the issue
will have to be revisited again."

* William P. Blair, research professor in the Department of Physics and
Astronomy and chief of observatory operations for NASA's Far Ultraviolet
Spectroscopic Explorer Satellite, operated by Johns Hopkins:
"I think the demotion of Pluto into the realm of other minor objects
outside the orbit of Neptune is the most consistent thing to do to
straighten out the nomenclature of our solar system. However, I don't find
the wording of the official planet definition to be very clear, and hence
it will continue to be open to interpretation.

"I find it comforting to know, though, that Pluto hasn't changed just
because of our nomenclature. It is the same today as it was yesterday, and
as it has been for thousands of years. It is still the most accessible of
the objects beyond Neptune that we can study, and studying it should reveal
much new information about the outer solar system."

* Richard Conn Henry, professor in the Department of Physics and Astronomy:
"I am delighted that rationality has prevailed! Keep in mind that our own
Sun is a dwarf star ... and Pluto is now a dwarf planet! Pluto is an
extremely interesting and important object, and I am overjoyed that NASA's
New Horizons mission is on its way to Pluto! Hurrah for Pluto, first dwarf
planet to be visited by a NASA mission!"

###
Received on Thu 24 Aug 2006 03:36:28 PM PDT


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