Flavin's Corner
1-29-99

System Check

Mother Very Easily Made AJam Sandwich Using No Peanuts, Mayonnaise,
or Glue*
A mnemonic for the planetary sequence and placement of the Asteroid Belt.

*Mercury, Venus, Earth, Mars, Asteroid Belt, Jupiter, Saturn, Uranus, Neptune,
Pluto, Mickey and Goofy.

     The momentum has been quietly building for a few years and last week the
International Astronomical Union (IAU) publicly announced they are seriously
considering the recategorization of Pluto and propose its downgrading from
'planet' status to either a "minor planet" or a vague "Trans-Neptune Object."
We've known Pluto as the ninth planet of our solar system, since its discovery
by Clyde Tombaugh in 1930, and if the IAU goes ahead with this change, it
may take some getting used to.  Perhaps a 'system check' is in order.

     Early humans were undoubtedly mystified by the Sun and Moon and there
is suggestive evidence that sufficient cognitive abilities were formed by the
Upper Paleolithic for the recognition of certain groupings of stars (i.e.,
constellations). [Note: see Dawn Behind The Dawn by Geoffrey Ashe, 1992,
Henry Holt: New York, and Ashe's theory of an early number "seven"
tradition, based on Ursa Major, which diffused from the Altai region of
Mongolia westward to Sumeria and subsequent Western fascination, and may
also have journeyed eastward with the Asians who became the Paleo-Indians of
the New World.]  With the rise of various Old World civilizations (and
"near-civilizations," as in the New World Aztec and Maya) certain "stars" were
identified as having peculiar movements and given special attention.  The
ancient Greeks referred to these irregularly moving "stars" as planetes, or the
"wanderers."

     The naked-eye astronomers of Mesopotamia, Egypt, China, and
Mesoamerica, recognized the five planets of Mercury, Venus, Mars, Jupiter,
and Saturn. [Note: there is a recent suggestion that Uranus may have been
observed by the Babylonians as early as Seleucid times and could have inspired
the enigmatic "Star of Bethlehem."  Click here for more.]  After the invention
of the telescope and its public demonstration to the ambassador of the King of
Siam by Prince Maurice of the Netherlands in 1608, Galileo read the report and
constructed his own telescope and later went on to observe the roughness of
the surface of the Moon, the satellites of Jupiter, and saw the "rings" of Saturn,
but died before correctly identifying them as such.  With improvements in
lensmaking techniques, the long standing list of five planets was finally
extended in 1781 with the official discovery of Uranus by William and Caroline
Herschel.

     Analyzing the orbit of Uranus in 1845, French and English mathematicians
Urbain Jean Joseph Le Verrier and John Couch Adams independently (and
without knowledge of the other's work) predicted the existence of another
planet.  The following year Le Verrier persuaded the astronomer Johan
Gottried Galle to look for the 'new' planet.  Le Verrier's predictions were so
accurate that Galle, together with his assistant Heinrich Louis d' Arrest,
discovered Neptune in less than 30 minutes after beginning their search.

     With the discovery of Neptune the number of planets orbiting the Sun rose
to eight (Earth being considered a planet after Copernicus and Galileo), and
there the number stayed until the 1930 discovery of Pluto.  For nearly 70 years
we have been used to nine planets. But now that's about to change.  Or is it?

     There is no generally accepted definition of what constitutes a "planet," but
most consider a planet to be a mass generated by swirling gas and dust which
did NOT become part of a sun.  Later, as the gases and dust joined, a process
of "hot accretion" and the combining of smaller planetessimals to form larger
'planets' occurred, or in the cases of the gas-giants Jupiter and Saturn, formed
'cores' for those worlds.  The process is far from completely understood, but a
key component of a planet appears to be a dynamic core, as opposed to some
moons, satellites, and Pluto, which possess inactive cores as a result of 'heavy'
metals sinking and 'lighter' materials forming a crust.  An inactive core, rather
than puny size or distance from the Sun, is the major reason the IAU is
downgrading the planet status of Pluto.  However, with this partial definition
of what constitutes a planet arising, we have another candidate ready to
occupy the position Pluto may soon vacate.  Luna, Earth's moon, seems to fit
the definition of a planet.

     As late as the mid-1960s, when I was a lad in grade-school, textbooks
claimed the moon came from the Pacific Ocean.  Some graphics showed the
moon fitting neatly between Asia and America and it made for an entertaining
explanation.  The better understanding of plate tectonics initially ruled out such
a possible origin for the moon, as did the Apollo voyages and the study and
age determination of moon rocks.  Ultimately the telescope returns as a
premier tool and visual inspection of the moon reveals signs of seismic activity
in the past, "moon-quakes" if you will.  Earth's "moon" had a dynamic core at
one time (and perhaps still does), ancient volcanoes spewed forth molten rock,
putting it into a category quite separate from other satellites.  Many scientists
today regard Luna as an example of a binary planet.

     Now, this is NOT to say the mystery of the origin of Luna is solved: it is
not.  At an estimated 4.5 billion years of age, it appears Luna developed
around the same time as the Earth.  Scientists still disagree about whether an
early collision with a large object (Mars?) separated the mass of Luna or if
Luna was formed and later captured in Earth's orbit.  Only future study will
tell.  However, with the evidence of an active core, Luna's upgrade to
planetary status seems eventual.

     Much like the dark rumors that Hawaii is considering independence from
the US, upsetting everyone involved with the flag-making industry and the
current design of 50 stars for 50 states, perhaps if Hawaiian independence
occurs we can put pressure on Puerto Rico to change its mind and become a
state.  So, the names would change, but the number would remain the same.
Perhaps a check of our solar system in a few years will produce the same
number of planets, only some of the names might be different.

rubbing sore neck from star-gazing,
Rick

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