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    Re: Smog and celestial navigation?!
    From: Jeremy C
    Date: 2010 Feb 2, 09:05 EST
    I can't comment before 1997, but this does make me think of Celnav in the waters off of Asia (East China Sea) in the last couple of years.  When I was near Japan and Korea, Celnav was spotty primarily due to very poor horizons.  I could have great stars, but often times nothing but a gray fuzzy horizon which rendered my sextant next to useless.  I don't know if this has always be so in those waters, or whether the recent pollution is to blame.
    For the rest of the water I've sailed in, I have had a decent run of good conditions with some days of poor horizons.
    In a message dated 2/1/2010 10:19:27 P.M. Eastern Standard Time, FrankReed@HistoricalAtlas.com writes:

    In a letter to the editor of the Sydney Morning Herald, April 5, 1976, I found a fascinating, and so "70s", theory about the possible obsolescence of celestial navigation. The letter is advocating "Omega" and says,
    "An alternative to sextant navigation has to be installed worldwide before the growing atmospheric pollution renders the sextant obsolete."
    "The periods of twilight have always been limited to a very few minutes. In the past 10 years, this period has been reduced to such an extent that it is already extremely difficult, in fact frequently impossible, to fix the ship's position at twilight.
    I refer specifically to the northern hemisphere from about the latitude of 10 degrees north. It seem to me, and I can only base this on what I have seen in 20 years of ocean navigation, that something is happening in the atmosphere up north."

    It sounded to me almost like some lines from "On the Beach," and at first I dismissed this as the rantings of a kook (and he may still be), but this guy was quite serious. So... does anyone on NavList think that smog has obscured the horizon significantly in the past few decades? I could imagine that it's a real issue in some local areas. Is celestial navigation today less viable today than it was fifty or sixty years ago because of smog obscuring the horizon??


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