A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2021 Jul 20, 07:08 -0700
Frank Reed you wrote: What's the dip from 100km altitude? And what's the distance to the horizon?
Average Earth diameter = (6378+6357)/2 = 6368km
By Pythagoras: Dist to horizon squared = 6468squared-6368squared=(6468+6368)x(6463-6368).
Dist to horizon= 1133km give or take a km or two.
Dip=90-(90-arccos(6368/6468)=10.09degrees or thereabouts.
Of course, I could be completely wrong. I don't go up there that often these days. DaveP