• THE AGE OF THE PLEIADES

    From Billy Lawter@RICKSBBS to All on Tue Jul 7 06:16:53 2026
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    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.
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    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.
    Billy,
    telnet://ricksbbs.synchro.net:23
    http://ricksbbs.synchro.net:8080
    IRC www://irccloud.com/irc/ricksbbs/channel/ricksbbs
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