Date: 12-17-91  16:50
From: Eric Greene

Ok... here's the information I have been able to dig out of various sources
of astronomical data including "The Astronomy Databook", Gaposchkin's "Stars
and Clusters" and Pasachoff's "Astronomy" From the Earth to the Universe"
about the Pleiades.

The age of the Pleiades:

The age of star clusters and how we go about obtaining such data is probably
best discussed in Cecila Payne-Gaposchkin's "Stars and Clusters" (Havard
Univ. Press).  Measuring the age of a cluster is a difficult chore and any
figures must be taken as estimates rather than exact numbers.  Basically,
stars of different mass, spectral types and luminosities evolve at different
rates.  A blue-white O type supergiant is consuming its mass at a furious
rate and only has a very short life expectancy measured in a few millions or
tens of millions of years.  Smaller, cooler stars like the Sun (G3 type) are
much more sparing of their mass and the sun is estimated to have a lifespan
of around 10 billion years.  Red dwarf type stars may last many more billions
of years.  The life of a star is measured not from the moment of its "birth"
until the time it ceases to exist, but is a measure of how long that star
will exist as a "main sequence" star - meaning how much of its life will be
spent in a certain area on the Hertzsprung-Russell diagram.  A star like the
sun may spend millions of years forming out of the galactic gas, a short time
as a proto-star, 10 billion years as a main sequence star, millions of years
as a red giant...etc. However, its life is measured in terms of how long on
the main sequence.

The estimates of the age of the Pleiades rest right around 100,000,000 years
making it a very young cluster in terms of the age of the galaxy.  Many of
even the smaller, fainter stars have not even reached the main sequence yet,
while the big, bright hot members have already expended much of their fuel
and are moving off the main sequence.  Such a cluster is a poor prospect for
life based on the evolution of life on earth.  The chances of life arising on
any planets orbiting Pleiadian stars is probably good, but the chances of
intelligent life arising in such a short period - again, based on the only
model we have studied - is slim.  It took 4 billion years for intelligent
life to arise on earth, and the chances of it happening in less than 3% of
that time is not considered likely.

The Distance to the Pleiades:

The most accurate means of measuring star distances is that of measuring the
absolute parallax using the 186 million mile diameter of the earth's orbit as
the base line.  Obviously the closer a star, the more accurate the distance
obtained.  Such parallax measurements are considered very accurate out to
about 100 light years and usable (with greatly increasing error) out to about
300 ly. Beyond 300 ly indirect measurements need be used. The most accurate
of the indirect measure techniques involve the use of standard "candles" -
objects of known brightness.  The most effective standard candles are the
Cephid variable stars.  Other methods of indirect measurement include radial
velocity studies, the orbits of double stars and, in many cases, flat out
guessing!
The best figures I can find for the distance of the Pleiades seems to be
around 410 ly.  Alcyone, the brightest star in the group, is listed as about
541 light years, but this apparent disparity only shows the wide margins for
error of any indirect measurement.  Of course, who knows what is actually
being talked about when discussing the distance to a star cluster.  Is it the
mean distance to all the stars, the distance to the closest star or what?
Determining which stars are evey part of a given cluster is not an easy job!

Astronomer's lives would be so much simpler if these Pleiadians and other
"star travelers" would stop with all their banal pronouncements about "peace
and living together in harmony"  (they ain't nothing new - our own
philosophers and teachers have been saying the same thing for thousands of
year) and start giving us basic scientific data.

The fact that out of all the thousands of so-called abductions, channeled UFO
information and the rest of the idle chatter there has never been a new,
VERIFIABLE piece of information must lead one to doubt the veracity of these
stories.