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  1. #1
    tony_flanders@yahoo.com's Avatar
    tony_flanders@yahoo.com Guest

    Default Dark Skies West, Dark Skies East



    Last new-Moon period, at the beginning of August, I set out from
    Boston in search of dark skies. I've been doing some work measuring
    sky brightness both with digital cameras and with the new Sky
    Quality Meter (http://unihedron.com/projects/darksky). I have
    a fair amount of data on urban, suburban, and typical rural
    sites, but I needed to supplement that with some information
    from darker areas.

    One glance at the North America map from the Light-Pollution
    Atlas (http://www.lightpollution.it/worldatlas/pages/fig2.htm)
    will reveal my predicament. West of longitude 100, well over
    half the area is colored gray or black, meaning that it has
    negligible light pollution. In the eastern half of the country,
    by contrast, there are only a few small dark enclaves.

    The underlying reason is obvious enough. Longitude 100W is the
    traditional limit of agriculture; west of that, rainfall is
    too low to support farming without irrigation. So not only are
    there fewer people in the West than in the East, but they're
    much more heavily concentrated. Put another way, the East has
    a large rural population dating back to the days when farming
    was the country's main occupation. In most of the West, the
    traditional ways to make a living in the countryside were
    ranching, mining, and logging, all of which are much less
    labor-intensive than family farms. People have been trickling
    into the Western countryside ever since, but it will be a long
    time, if ever, before it's as densely populated as the East.
    After all, it's *still* hard to make a living there. Besides,
    people can't live without water, which is abundant in the
    East and scarce throughout most of the West.

    In addition to being abundant, dark areas in the West are
    relatively accessible. That's because the great majority of
    the West is owned by the U.S. government, and protected from
    development. So you get huge, densely populated suburbs
    butting directly against total wilderness -- a situation
    ideal for mountain lions with a taste for human flesh and
    also for amateur astronomers.

    People familiar with the northeastern U.S. will not be
    surprised that the two biggest dark enclaves are in Maine
    and New York State. The one in New York is (as in the West)
    due largely to government regulation. Adirondack State
    Park is enormous -- just a tad smaller than Massachusetts,
    the state that I live in. But it's sprinkled with private
    in-holdings, making it less dark than Maine.

    The dark area in Maine, extending also into a corner of
    New Hamsphire, is even bigger, and it's owned by a handful
    of paper companies. Traditionally, they have remained on
    good terms with the locals first by providing employment
    and second by allowing free access for hunting, fishing,
    hiking, and boating -- all the while rigorously opposing
    development. Now that the price of wood pulp is low and
    traditional local owners have been replaced by faceless
    international corporations, there's great fear that the
    traditional equilibrium will disappear. But for the
    moment, north-central Maine remains almost completely
    unpopulated, and very dark.

    As it happens, it was cloudy on the night that I set
    aside to explore the Maine/New Hampshire border area.
    But I saw enough to remember that in some ways,
    getting away from major light sources is the easy
    part. The problem with the North Woods -- or any
    sparsely populated area in the U.S. Northeast --
    is finding an area without trees. The West is amply
    supplied with deserts, grasslands, and mountain
    meadows, but the only natural clearings here are
    swamps, lakes, and rivers. And even the banks of
    lakes and rivers are often so overhung by trees
    that you can barely glimpse the sky from them.

    My first forray from Boston was to a less dark area,
    colored blue on the Light Pollution Atlas (like, say,
    Cherry Springs in PA, Monitor Pass in CA, or Mt.
    Graham in AZ). This is the White Mountain National
    Forest in New Hamsphire, a nearly contiguous chunk
    of land some 30 miles square. It has relatively few
    in-holdings, but unfortunately it's ringed round by
    large towns or small cities that used to be based
    on paper mills and now depend largely on tourism.
    And it's southern edge is only a 100 miles from
    Boston -- easily close enough to be affected by
    the lights of the Boston suburbs, which have now
    enveloped what used to be independent cities in
    southern New Hampshire.

    Anyway, without a doubt *the* most obvious place to
    do astronomy within the WMNF -- and probably the most
    accessible "blue" site from Boston -- is the scenic
    viewing area at the height of land on the Kancamagus
    Highway -- a highway which was built right across the
    heart of the wilderness in the 1950's. (It would never
    in a million years be allowed now.) It has low but
    significant light domes from the tourist boom towns
    of Lincoln and North Conway, and a huge diffuse glow
    to the south from the populated areas of southern
    New Hampshire and the Boston suburbs. And it suffers
    from the problem of being *too* obvious -- there was
    a steady stream of people stopping by until I left
    at 1:30 a.m., many of them none too careful about
    using white lights.

    Nonetheless, observing from Kancamagus Pass was a
    revelation. People around here often say that you
    can't get good views -- as you can in the West --
    because the air is too thick and humid. But that's
    not the problem at all! It's just that dark sites
    are so hard to find that we become accustomed to
    settling for a grossly inferior standard. For
    instance, Stellafane, where I was a few nights
    later, is *dramatically* brighter than Kancamagus
    Pass -- really no comparison at all. And Kancamagus
    Pass is still far from pristine.

    I still remember my first naked-eye views of M16
    and M17, from the Lassen National Park in California.
    I wasn't looking for them at all -- I just saw two
    obvious bright spots, wondered what they could be,
    then realized that they were exactly where those
    objects ought to be, and finally confirmed the
    sightings with binoculars. Sure, Lassen is an
    extraordinary site, but Kancamagus Pass isn't
    all that much worse. Again, M16 and M17 popped
    right out, unbidden, even though I was a good
    5 degrees farther north, with the objects that
    much lower in the sky.

    Some time, I'll make it up to north-central Maine
    on a clear night. I'm quite curious to see how much
    practical difference there is between it and the
    White Mountain National Forest. But it's a mighty
    long drive.

    - Tony Flanders


  2. #2
    starburst's Avatar
    starburst Guest

    Default Dark Skies West, Dark Skies East

    tony_flanders@yahoo.com wrote:
    <Pleasant, interesting and on topic info snipped>

    Nice post, Tony, thanks.

    C

  3. #3
    CNJ999's Avatar
    CNJ999 Guest

    Default Dark Skies West, Dark Skies East


    tony_flanders@yahoo.com wrote:

    Yes, Tony, that is precisely the case. Although it is many years ago
    now, I can still remember when 90% of the Northeast enjoyed skies like
    you saw at Kancamagus. One needed to drive no more than 20-25 miles
    outside any major metropolitan area to get skies as dark or darker than
    those that can be found at most of the major Southwestern observatories
    today.

    Regarding Stellafane's skies, they have deteriorated significantly over
    the past 20 years and are but a shadow of what they once
    were...although you'll still hear urban newcomers to the hobby gasp
    when they see them!

    JBortle


  4. #4
    DustyMars's Avatar
    DustyMars Guest

    Default Dark Skies West, Dark Skies East

    In article <1125531079.375368.6150@f14g2000cwb.googlegroups.c om>,
    tony_flanders@yahoo.com says...
    Not many places out east with dark sky. A shame.

  5. #5
    allisonki@IGNmail.com's Avatar
    allisonki@IGNmail.com Guest

    Default Dark Skies West, Dark Skies East

    I saw a news article today in which the reporter, who is in New
    Orleans, described last night's sky as "perfectly black". I suppose
    that there may be quite a bit of air pollution, though, from the fires
    and so forth.


 

 

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