NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2025 Mar 8, 07:05 -0800
Yes, I got roughly 12m using the Earth as an angular scale, too. But I don't really trust the angular size of the Earth. Cameras like this and display processing often significantly change the angular scale between the center and the edges of the field of view. Another approach: the penumbra around the umbral shadow of the spacecraft also determines a scale. What do you get by that method?
I'm including a photo I took a few months ago outside my back door here, specifically designed to illustrate "distance by penumbra". If anyone feels like working out distances, you'll want to know that the width of that maple leaf below and to the left of the image center, nearly at pixel x=240 and y=325 (with 0,0 at upper left), was just about 10cm.
In the photo on the lunar surface, certain aspects of photo contrast may limit the value of this shadow technique.
Frank Reed
