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: The Three-body Problem
    From: Peter Monta
    Date: 2021 Oct 25, 22:46 +0000
    Hi Bob,

    Is there any connection here with leap seconds?  I have always understood them to be related to irregular slowing (or, in principle, speeding up) of the rotation of the earth.  Is any portion of the leap second related to actual irregular variations in the orbit of the earth about the sun?

    The second was once defined by the Earth's orbit around the Sun, and indeed the secular change of the tropical year was accounted for in the second's definition under that scheme (there was a term in T^2).  This is already pretty complicated; the tropical year was chosen for some technical reason for which I don't know the particulars.  This definition of the second was shortly replaced by the atomic second, partly because the (empirical?) "acceleration" terms rendered it not very fundamental.

    But, despite all this, I think the brief answer is no, leap seconds are not influenced by any variation of the orbit of the Earth around the Sun.  Leap seconds are purely to keep UTC true to Earth rotation.  If the year were to vary slightly (independently of Earth rotation), that would affect the seasons, yes, but it would not be a driver for adding or subtracting leap seconds under the current system.


    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