Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: Basics of computing sunrise/sunset
    From: Douglas Denny
    Date: 2009 Jun 18, 11:27 -0700

     Douglas, I hope this is not something I should be worried about.  I spent
    about 20 of my 32 years in this southern region and I guess I had a good
    deal of exposure to the local sun, but I'd still say it was in limits, being
    aware of the UV-light  issue (am knocking on wood). The ozone hole expanded
    closer and closer to South Africa and may even already have reached the
    "sky" over South Africa in the late eighties when I was growing up.
    I do not think so if your vision is still good after 20 years of doing this.
    The cautionary way forward though is not to expose your eyes to known 
    potential high intensity radiation in the infra-red or UV, which is what 
    telescopes or binocs do: they gather more light radiation and concentrate it 
    into the fovea.  It does the same thing a surgeon does to seal off 
    micro-heamorrages in diabetes with a laser coagulator.
    Douglas Denny.
    Chichester.  England.
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site