Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Venus transit June 8 and sextants
    From: Frank Reed CT
    Date: 2004 May 12, 06:17 EDT
    Robert E asked:
    "Why is this dangerous?  Is it because there is a possibility of the shades
    slipping out of position?"

    In a way, yes.

    Fundamentally, it is dangerous because there is a telescope in the light path. This is intrinsically dangerous when you're looking at the Sun. If you carry this risk alone, then there's no problem. But do you??

    Imagine yourself out on a street corner with your sextant on June 8th. You know what you're doing; nothing could go wrong. And you say to yourself, 'I know what I'm doing... nothing could go wrong..."   So you demo your sextant to your neighbor who happens to have heard about the transit of Venus today and is enthusiastic to see the show. And you're pleased to show the show... You swing the shades one way.. you swing them back... you demo the sight... You hand the sextant to your neighbor and before you've noticed he swings the shades out and looks straight through at the Sun. He jumps away quickly but it's too late. He's got a blindspot. He has permanent damage to his eye. And you've got a legal and moral nightmare.

    That's a parable, of course, but the fundamental concept stands; it's error-correction. So what do you do? How do you avoid the potential for a minor error with major consequences when you're casually using a sextant to observe the Sun?

    Frank R
    [ ] Mystic, Connecticut
    [X] Chicago, Illinois
       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

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