[meteorite-list] 'Plutons' Push Planet Total Up To 12

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Wed Aug 16 00:15:47 2006
Message-ID: <008e01c6c0ea$a2a85960$6a4fe146_at_ATARIENGINE>

Hi, Ron, List


    The Sydney Morning Herald says:
>Quote<
    "A planet, they [the Committee] decreed, is any
star-orbiting object so large that its own gravity pulls
in its rough edges, producing a near-perfect sphere."


Sterling K. Webb
--------------------------------------------------------
----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Tuesday, August 15, 2006 10:54 PM
Subject: [meteorite-list] 'Plutons' Push Planet Total Up To 12


>
> http://news.scotsman.com/scitech.cfm?id=1194292006
>
> 'Plutons' push planet total up to 12
> JOHN VON RADOWITZ
> The Scotsman
> August 15, 2006
>
> A NEW kind of planet, the "pluton", could soon be taking its place in the
> Solar System.
>
> Astronomers have agreed on a draft proposal for redefining what
> constitutes a planet.
>
> If approved at a meeting underway in the Czech capital, Prague, school
> science text books will have to be re-written.
>
> The new definition would mean there are 12, not nine planets, and more
> could be added to the list in the future.
>
> They include eight "classic" planets - Mercury, Venus, Earth, Mars,
> Jupiter, Saturn, Uranus and Neptune - Ceres, currently considered an
> asteroid, and three "plutons," one of which is Pluto.
>
> The other plutons are Charon, currently described as a moon of Pluto,
> and the newly-discovered object 2003 UB313, which has not been named
> officially, but is nicknamed Xena.
>
> Ceres is the largest object in the asteroid belt between Mars and
> Jupiter, and like a planet is spherical in shape.
>
> A resolution to accept the new planet definition will be voted on by
> members of the International Astronomical Union (IAU) next Thursday,
> 24 August. If passed, the days of simply learning the names of the
> nine planets will be over for the world's schoolchildren. In future,
> many more planets could join the Sun's family as other plutons are
> discovered.
>
> A dozen "candidate planets" are already on the IAUs "watchlist". They
> include Varuna, Quaor and Sedna, all Pluto-like objects residing
> within a region on the fringe of the Solar System known as the
> "Kuiper Belt".
>
> Plutons differ from classical planets in that they have orbits round
> the Sun that take longer than 200 years to complete, and their orbits
> are highly-tilted and non-circular.
>
> All these characteristics suggest that they have an origin different
> from that of classical planets.
>
> The IAU has taken two years working out the differences between planets
> and smaller Solar System bodies such as comets and asteroids.
>
> IAU president Professor Ron Ekers said: "Modern science provides much
> more knowledge than the simple fact that objects orbiting the Sun
> appear to move with respect to the background of fixed stars.
>
> "For example, recent new discoveries have been made of objects in the
> outer regions of our Solar System that have sizes comparable to and
> larger than Pluto.
>
> "These discoveries have rightfully called into question whether or not
> they should be considered as new 'planets'."
>
> According to the new draft definition, two conditions must be satisfied
> for an object to be called a "planet".
>
> First, the object must be in orbit around a star, while not itself
> being a star. Second, and most importantly, it must be massive enough
> for its own gravity to pull it into a nearly spherical shape.
>
> The IAU, responsible for the naming of planets and moons since 1919,
> set up a Planet Definition Committee (PDC) to consider the problem.
> Committee member Professor Richard Binzel said: "Our goal was to find a
> scientific basis for a new definition of planet, and we chose gravity
> as the determining factor.
>
> "Nature decides whether or not an object is a planet."
>
> Mnemonic needed
>
> IF ASTRONOMERS decide to change the number of planets in our solar
> system then piles of science textbooks will have to be rewritten.
>
> Generations of children have learned the names of the planets using
> mnemonics, listing the celestial bodies in their order from the Sun.
>
> "My Very Eager Mother Just Sent Us Nine Pies" is one popular aide
> memoir, helping students to remember Mercury, Venus, Earth, Mars,
> Jupiter, Saturn, Uranus, Neptune and Pluto.
>
> Other useful phrases include "Make Very Easy Mash - Just Squash Up
> New Potatoes" and "My Very Easy Method Just Showed Us Nine Planets".
>
>
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Received on Wed 16 Aug 2006 12:15:40 AM PDT