Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_7/V13_702.TXT

Internet Message Format | 1991-06-24 | 25KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/0cNQQwi00WBw08jE4z>;
          Mon, 24 Jun 91 06:19:40 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Mon, 24 Jun 91 06:19:35 -0400 (EDT)
Subject: SPACE Digest V13 #702

SPACE Digest                                     Volume 13 : Issue 702

Today's Topics:
          Electronic Journal of the ASA - June 1991

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

----------------------------------------------------------------------

Date: 6 Jun 91 15:20:29 GMT
From: nntpd.lkg.dec.com!rburns.enet.dec.com![e-mail]  (Larry Klaes)
Subject: Electronic Journal of the ASA - June 1991


                        THE ELECTRONIC JOURNAL OF
                THE ASTRONOMICAL SOCIETY OF THE ATLANTIC

                     Volume 2, Number 11 - June 1991

                       ###########################

                            TABLE OF CONTENTS

                       ###########################

         * ASA Membership/Article Submission Information

         * Sir William Herschel and the Natural History of the Heavens

              - Keith M. Parsons

         * Curbing Light Pollution in Ohio - Robert Bunge

                       ###########################

                       ASA MEMBERSHIP INFORMATION

        The Electronic Journal of the Astronomical Society of the
    Atlantic (EJASA) is published monthly by the Astronomical Society
    of the Atlantic, Inc.  The ASA is a non-profit organization dedicated
    to the advancement of amateur and professional astronomy and space
    exploration, and to the social and educational needs of its members.

        ASA membership application is open to all with an interest in
    astronomy and space exploration.  Members receive the Journal of the
    ASA (hardcopy sent through U.S. Mail), the Astronomical League's
    REFLECTOR magazine, and may additionally purchase discount subscrip-
    tions to ASTRONOMY, DEEP SKY, ODYSSEY, SKY & TELESCOPE, and TELESCOPE
    MAKING magazines.

        For information on membership, you may contact the Society at
    any of the following addresses:

         Astronomical Society of the Atlantic (ASA)
         c/o Center for High Angular Resolution Astronomy (CHARA)
         Georgia State University (GSU)
         Atlanta, Georgia  30303
         U.S.A.

         [e-mail]

         ASA BBS: [phone], 300/1200 Baud.

        or telephone the Society Recording at [phone] to leave
    your address and/or receive the latest Society news.

        ASA Officers and Council -

         President - Don Barry
         Vice President - Nils Turner
         Secretary - Ken Poshedly
         Treasurer - Alan Fleming
         Board of Advisors - Edward Albin, Bill Bagnuolo, Jim Bitsko
         Council - Jim Bitsko, Bill Crane, Toni Douglas, Eric Greene,
                   Larry Klaes, Tano Scigliano, Bob Vickers,
                   Michael Wiggs, Rob Williams


        ARTICLE SUBMISSIONS -

        Article submissions to the EJASA on astronomy and space exploration
    are most welcome.  Please send your on-line articles in ASCII format to
    Larry Klaes, EJASA Editor, at the following net addresses or the above
    Society addresses:

        [e-mail]
        or - ...!decwrl!rburns.enet.dec.com!klaes
        or - [e-mail]
        or - [e-mail]

        You may also use the above net addresses for EJASA backissue
    requests, letters to the editor, and ASA membership information.

        When sending your article submissions, please be certain to include
    either a network or regular mail address where you can be reached, a
    telephone number, and a brief biographical sketch.

        DISCLAIMER -

        Submissions are welcome for consideration.  Articles submitted,
    unless otherwise stated, become the property of the Astronomical
    Society of the Atlantic, Inc.  Though the articles will not be used for
    profit, they are subject to editing, abridgment, and other changes.
    Copying or reprinting of the EJASA, in part or in whole, is encouraged,
    provided clear attribution is made to the Astronomical Society of the
    Atlantic, the Electronic Journal, and the author(s).  This Journal is
    Copyright (c) 1991 by the Astronomical Society of the Atlantic, Inc.


          SIR WILLIAM HERSCHEL AND THE NATURAL HISTORY OF THE HEAVENS

                              by Keith M. Parsons

        In the book TIMAEUS, the Greek philosopher Plato (circa 427-347
    B.C.) tells us that the Demiurge, the deity of the material world,
    patterned existence after the eternal forms.  However, the perfection
    of an eternal being cannot be completely conferred upon a generated
    thing, so the heavens were made "a moving likeness of eternity."  In
    other words, since a physical universe must be subject to motion, the
    best sort of motion is everlastingly the same.  Thus, the heavens,
    which move endlessly in perfect circles, are as close to the change-
    less perfection of the forms as a created thing can be.

        No view could be more alien to the universe of contemporary
    astronomy than such a picture of serene, changeless perfection.  We
    now know that stars are born and die, that celestial events are
    turbulent and frequently violent, and indeed, that the Universe itself
    is expanding and evolving.  This vast change of cosmic perspective
    was, of course, the product of centuries of labor by many different
    persons. However, as long as astronomy's attention was focused on the
    planets, moons, and comets of Earth's solar system - which it was
    until well after Sir Isaac Newton's (1642-1727) day - the evolutionary
    concept of the Universe could make little headway.  Despite German
    philosopher Immanuel Kant's (1724-1804) prescient speculations, it was
    only when the British astronomer Sir William Herschel (1738-1822) began
    the systematic study of the stars and nebulae did the natural history
    of the heavens become possible.

        Astronomers had long been aware of faint, diffuse patches of
    luminosity scattered among the sharp, point-like lights of the stars.
    Before Herschel, few astronomers had shown much interest in such
    nebulae.  Many, like Charles Messier (1730-1817), regarded them as a
    nuisance; Messier's famous catalogue of the nebulae was intended to
    help comet hunters avoid misidentifying nebulae as new comets.

        Herschel, by making for himself the best telescopes that had yet
    been available for astronomers, was able to make an important dis-
    covery, which he announced in a paper read to Great Britain's Royal
    Astronomical Society (RAS) on June 17, 1784:

        "The excellent collection of nebulae and clusters of stars which
    has lately been given in the CONNOISSANCE DE TEMPS for 1783 and 1784
    [Messier's Catalogue], lead me next to a subject which, indeed, must
    open a new view of the heavens.  As soon as these volumes came into my
    hands, I applied my former 20-foot [six-meter] reflector of 12 inches
    [thirty centimeters] aperture to them and saw, with the greatest
    pleasure, that most of the nebulae, which I had the opportunity of
    examining in proper situations, yielded to the force of my light and
    power, and were resolved into stars."

        Herschel then states that many of the nebulae regarded by Messier
    as without stars had either been definitely resolved into stars or
    gave every indication that they could be so resolved.

        Herschel was overly optimistic; some of the nebulae he mentions
    are, in fact, galaxies and not so resolvable into stars by any of
    Herschel's telescopes.  Other nebulae, such as Messier 1 (M1, now
    known as the Crab Nebula, the remnant of a supernova first seen on
    Earth in 1054 A.D.), are in fact, non-stellar and are constituted of
    diffuse clouds of glowing gas.  Herschel, of course, had no way of
    knowing that the Messier objects would ultimately turn out to be so
    diverse (they are now recognized to comprise globular clusters, open
    clusters, galaxies, planetary nebulae, supernova remnants, and several
    other types of celestial objects).  Hence, it was reasonable to
    hypothesize, as Herschel did at first, that all nebulae would prove
    resolvable as more and more powerful telescopes were built.

        In a paper delivered to the Royal Astronomical Society less than
    one year after the one quoted above, Herschel proposed that the nebulae
    are formed when randomly scattered stars are drawn together through
    mutual gravitational attraction.  Herschel, in a remarkable passage,
    imagined an observer's expanding conception of the Universe.

        At first, the observer will think that the entire Universe is
    contained in a few constellations.  He will see the light of distant
    stars as only a milky luminosity.  But, says Herschel, let him now
    have use of a telescope:

        "...he begins to suspect that all the milkiness of the bright path
    which surrounds the sphere may be owing to stars....He now increases
    his power of vision and, applying himself to a close observation,
    finds that the milky way is indeed a collection of very small stars.
    He perceives that those objects which had been called nebulae are
    evidently nothing but cluster of stars....He forms the idea of immense
    strata of fixed stars, of clusters of stars and nebulae."

        Indeed, says Herschel, the observer will conclude that he inhabits
    only a single cluster, not necessarily the largest, in this vast
    system of clusters upon clusters upon clusters.

        It is remarkable to see how easily Herschel accepts the concept
    of a Universe of previously unimaginable vastness.  It is even more
    remarkable to see the degree to which he anticipates contemporary
    cosmology with its talk of clusters and superclusters and galaxies.

        Nevertheless, Herschel came to realize that his scheme was
    simplistic and did not square with certain phenomena.  In fact, some
    nebulae simply did not appear to be of a starry nature.  The Great
    Nebula in the constellation of Orion the Hunter, for instance, is so
    extensive that, if it is so far away that even Herschel's largest
    telescope cannot resolve it into stars, its actual size must be
    unreasonably huge even by Herschel's standards.  Further, Herschel had
    observed a number of what today are called "planetary" nebulae.  These
    nebulae, constituted of matter shed by old, giant stars, frequently
    take the form of a nebulous ring surrounding a bright star in the
    center.  Herschel concluded that if the nebulosity in this case is
    caused by the concentration of distant stars, those stars must be much
    smaller than the central star.  Indeed, either the central object is
    so huge, or the surrounding ones so small, that one or the other
    should not be considered of stellar nature.  Herschel therefore
    concluded that there are cases of true nebulosity, i.e., that some
    nebulae are not stellar but are constituted of a "shining fluid" of
    unknown nature.

        Herschel sought to incorporate true nebulae into his evolutionary
    scheme.  By 1811, he believed he had succeeded.  Numerous observations
    had convinced him that the nebulae formed a graded series with coarse
    star clusters (such as the Pleiades) at one end and extensive, diffuse
    nebulosities (such as the Great Nebula in Orion) at the other end.
    Further, between these extremes, Herschel believed that he had observed
    every possible gradation of nebulae types.  He therefore concluded that
    this series constituted an evolutionary sequence:  Diffuse nebulae
    gradually condense to form stars which then, through the action of
    mutual gravitation, join with other stars to form clusters of various
    sorts.

        Herschel now believed he had a true natural history of the heavens.
    In one famous passage, he compares the Universe to a luxuriant garden
    in which we may find the greatest variety of productions flourishing
    in different beds.  Further, we see specimens in every stage of growth,
    maturity, and decay, so we know their natural history just as if we had
    watched a single specimen pass through these stages.  According to
    Herschel, we therefore, inhabit a dynamic Universe that evolves over
    great spaces and vast stretches of time.

        Herschel was ultimately wrong, of course, in placing all nebulae
    in a single evolutionary sequence.  As mentioned earlier, many diffe-
    rent types of objects were called "nebulae" in Herschel's day.  Never-
    theless, Herschel's evolutionary approach was a fruitful one, and
    much subsequent astronomy can be viewed as a series of emendations or
    footnotes to his scheme.  For instance, that stars are formed from
    condensing clouds of gas and dust is a tenet of contemporary astronomy;
    the Orion Nebula itself is believed to be such a stellar nursery.
    Herschel oversimplified, which is only to be expected when work on a
    major problem is just getting started, but his basic insights were
    sound.

        Herschel was an enormous success, both as a theoretician and an
    observer.  He also discovered the planet Uranus in 1781, infrared
    radiation, and binary star systems.  One thing his success did show
    is that there is a place for the methods and practices of natural
    history, even within a highly theoretical science.  It was Herschel's
    skill as a natural historian, the astonishing patience and thoroughness
    he displayed in his systematic surveys of the whole sky, that provided
    the massive amounts of observational data he used to back up his theor-
    ies.  More than that, Herschel showed that the simple desire to observe
    carefully and describe accurately, plus the willingness to abandon
    hypotheses in the light of new evidence, are indeed virtues conducive
    to the highest scientific achievement.

        References and Further Reading -

         Berry, Arthur, A SHORT HISTORY OF THE HEAVENS, Dover Publica-
           tions, New York, 1961

         Herschel, Sir William (Michael Hoskins, editor), WILLIAM
           HERSCHEL AND THE CONSTRUCTION OF THE HEAVENS, Oldbourne Book
           Co., London, 1963

         Kant, Immanuel, UNIVERSAL NATURAL HISTORY AND THEORY OF THE
           HEAVENS, 1755

        About the Author -

        Keith Parsons earned his first Ph.D. in the Philosophy of Religion,
    which led to an academic career.  Keith later chose to leave this pro-
    fession to earn a second Ph.D. in the Philosophy of Science, which he
    is currently pursuing at the University of Pittsburgh in Pennsylvania.
    Keith's interests have led to a strong interaction with members of the
    Center for High Angular Resolution Astronomy (CHARA) and an interest
    in skeptical inquiry and philosophy of the scientific method.


                        CURBING LIGHT POLLUTION IN OHIO

                                by Robert Bunge

        What are, perhaps, the first light regulations in Ohio were passed
    in early April of 1991 by the zoning committee of Liberty Township in
    Delaware County.  Perkins Observatory, one-time location of the largest
    telescope east of the Mississippi River, a 173-centimeter (69-inch)
    reflector now in Flagstaff, Arizona, and current home of the "Big Ear"
    radio telescope, are located in Liberty Township.

        These regulations are the brainchild of Doctor Robert Dixon,
    assistant director of the Big Ear radio telescope.  Dixon, a resident
    of Liberty Township, served on a zoning committee that made suggestions
    for controls to handle rapid growth in the forty-kilometer (twenty-
    five-mile) wide township to the township zoning board, which then
    sorted through the suggestions and started the long process that
    turns them into law.  Dixon's proposed lighting regulations received
    support from the zoning board once they understood the problem of
    light pollution.

        The passing of these laws is an important victory for lovers of
    the night sky in Ohio, not only because of the location of Perkins
    Observatory, site of a recent series of highly successful public
    programs conducted by the Columbus Astronomical Society, but also
    because the county is the primary target of rapid growth from the
    nearby state capital of Columbus to the south.  Recent trends in
    expansion from Columbus have been knocking on the doors of Delaware
    County over the course of the past five years.  While much of the
    new construction does use full-cut off, or fully shielded, lighting
    fixtures, much more does not.

        The timing for the new laws was critical.  As Dixon pointed out,
    zoning laws are difficult to change.  It requires public hearings,
    lawyers, and much discussion to make even a small change.  As a
    result, many smaller towns, counties, and townships only make zoning
    changes every few years.  The new lighting laws in Liberty Township
    were only a small part of a much larger rewrite of the zoning laws.
    Thus, the time to approach a township to write in lighting controls
    is not just after they have made changes, but before they do so.

        The new Liberty Township regulations require that all outdoor
    lighting in the township be pointed downward and fully shielded. This
    not only helps reduce light pollution, but also light trespass, which
    is when light from a neighbor is allowed to shine onto another's
    property.  The regulations also require that outdoor lighting not
    actually being used for practicable purposes be turned off at 11:00
    p.m..

        Even though most astronomers would consider these controls to be
    reasonable, many people have a difficult time, at first, in under-
    standing them.  Dixon said when he first proposed the regulations,
    there was a good bit of opposition, ranging from churches interested
    in lighting their buildings to patriots who were interested in flying
    the United States flag all night.

        To answer these arguments, Dixon used a tried and true technique
    when it comes to getting things done in low-level government:  Public
    speaking.  Dixon arranged to give presentations to local groups and at
    public hearings that were held on the new regulations.  As a tool to
    assist the effort, he used slides that are designed to present the
    problem of light pollution to the general public, sold by the
    Astronomical Society of the Pacific (ASP).

        "I could have talked and talked, but without those slides I would
    have never convinced many people," Dixon said.  By the time the
    regulations were up for a final vote by the zoning board, the only
    opposition was that regulating lighting was "going too far".  "Most
    people who live in Liberty Township do so because they want to live
    in the country.  A dark sky is part of being in the country, so few
    people were opposed to (the regulations) once they understood them,"
    Dixon said.

        The wording and general directions of the regulations were
    patterned after those suggested by the International Dark-Sky
    Association, an organization of persons interested in preserving the
    night sky and saving energy, said Dixon.  Dixon is not ready to stop
    yet.  He hopes to expand the controls to nearby townships and cities
    as they try to revamp their zoning laws in the near future.

        Resources -

         Astronomical Society of the Pacific (ASP)
         Catalog Department
         390 Ashton Avenue
         San Francisco, California 94112
         U.S.A.

          Slide set - AS 294, $19.95
          LIGHT POLLUTION: PROBLEMS AND SOLUTIONS

         International Dark-Sky Association
         3545 North Steward
         Tucson, Arizona 85716
         U.S.A.

          Individual membership - $20.00
          (Can accept Master/Visa Card)
          IRS registered 501-c-3 non-profit organization

    -----------------------------------------------------------------

        The Lighting Regulations of Liberty Township, Delaware County, Ohio

        Section 21.04 - Lighting Regulations

        1.  GENERAL REQUIREMENTS - All lighting shall be controlled in
    such a way as to not shine up into the sky or onto any neighboring
    properties.  Examples of ways in which this shall be accomplished are:

        a) Use of fully shielded cut-off fixtures;

        b) Directing light fixtures downward rather than upward;

        c) Shielding the light in such a way that the light emitting
           portion of the fixture cannot be seen at a reasonable distance.

        2.  SPECIFIC REQUIREMENTS

        a) Where used for security purposes or to illuminate walkways,
           roadways, equipment yards, and parking lots, only fully shielded
           cut-off style outdoor light fixtures shall be utilized.

        b) Where used for signs or for decorative effects or recreational
           facilities, such as for building, landscape, or ballfield
           illumination, the outdoor light fixtures shall be equipped with
           automatic timing devices and shielded and focused to minimize
           light pollution.

        c) All outdoor light fixtures installed and maintained upon
           private property within all zoning districts shall be turned off
           between 11:00 P.M. and Sunrise EXCEPT when used for security
           purposes or to illuminate walkways, roadways, equipment yards,
           and parking lots.

        d) All illuminated signs for commercial purposes shall be turned
           off between 11:00 P.M. and Sunrise, EXCEPT that signs may be
           illuminated while the business facility is open to the public.
           All forms of flashing, rotating, moving, or digital lights shall
           be prohibited.

        e) All outdoor light pole fixtures shall not exceed a maximum
           height of nine (9) meters (thirty (30) feet).

        f) In addition to the provisions of this Article all outdoor
           light fixtures shall be installed in conformity with all other
           applicable provisions of this Resolution.

        3.  EXEMPTIONS

        a) All outdoor light fixtures producing light directly by the
           combustion of fossil fuels, such as kerosene lanterns or gas
           lamps, are exempt from the requirements of this Section.

        b) All low-voltage lighting and holiday lighting shall be exempt
           from the requirements of this Section.

    -----------------------------------------------------------------

        Related EJASA articles -

         "Stopping Space and Light Pollution", Larry Klaes and
          Phil Karn - September 1989

         "When the Light Gets in Your Eyes, You Shouldn't Have to
          Drive to the Country", James Smith and Ken Poshedly -
          February 1991

        About the Author -

        Robert Bunge is an amateur astronomer and telescope builder,
    originally from Columbus, Ohio, who likes to observe all types of
    objects.  Robert has had articles published in ASTRONOMY, SKY &
    TELESCOPE, and TELESCOPE MAKING magazine.  Robert is a contributing
    editor for DEEP SKY magazine.

        Robert may be contacted at Internet address [e-mail]

        Robert is the author of "Stephan's Quintet" in the February 1991
    issue of the EJASA.


     THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC

                         June 1991 - Vol. 2, No. 11

                          Copyright (c) 1991 - ASA

------------------------------

End of SPACE Digest V13 #702
*******************