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: Submarine celestial through periscope
    From: Frank Reed
    Date: 2023 Mar 13, 13:16 -0700


    In your post earlier today, you included this images with "cones of position" terminating at points on the celestial sphere. Where is that from? It's clearly a professional illustration from a book dating back some decades. But it appears to me that the creator of the image has thoroughly misunderstood the concept. The cones are backwards.

    I was getting ready to go digging for some of my old artwork on this concept, and then I noticed that you actually referenced one of my old webpages, http://fer3.com/cones/, on this concept dating back 17 years (so shockingly long ago that I grabbed my calculator to make sure that 2023-2006 actually equals 17!). A two-star fix understood as two circles of position on the Earth's surface can be extended off the surface of the Earth as two cones of position, but the "pointy ends" of those cones are at the Earth's center. The old diagram that you found with the cones' pointy ends on the stars on the "celestial sphere' really doesn't even make sense as a visual aid. It's an oddity!

    Frank Reed
    Clockwork Mapping / ReedNavigation.com
    Conanicut Island USA


    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