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: Celestial in the thin air!
    From: Frank Reed
    Date: 2020 Jun 5, 13:27 -0700

    Hello Suzanne. Glad to see you found the NavList message boards. As I said when you emailed, it's a helpful group.

    You asked Michael Jones:
    "can I make the program Stellarium show the view from 20,000 feet where the air is thin and cold?"

    If anyone else knows a better method, I apologize for my interruption, but I do know of one way to do this. In Stellarium, hit the F4 key on your keyboard. This will open the Sky and View Options dialog. On the Sky tab (first one up when the dialog opens), you'll see "Refraction/Extinction settings". You can lower the pressure in millibar to a very low level. This doesn't make the sky black in daylight, as it should, but it does reduce the refraction properly, in direct proportion to the pressure. In the troposphere, the density of the atmosphere falls with height at a rate of about 10% per kilometer (in a "cumulative interest", geometric growth sense, so at each km of altitude, it's 10% lower than the km just below it). The density of the air at the tropopause (bottom of the stratosphere, approx. 11km or 36,000 feet above sea level) is about 30% of the density at sea level. So if you use 300 mb pressure in Stellarium and leave the temperature unchanged, you should closely simulate the apparent refraction up there. I'm sure you can work out the pressure in mb for 20,000 feet equivalent yourself.

    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