A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2019 Jan 21, 11:15 -0800
Spherical trigonometry is tricky or counter-intuitive at times. :)
I wondered how comes - the Sun is barely above the horizon at LAN (~10°) but the Moon the very same evening mer-passes nearly at zenith? Its' orbit is ~5° to ecliptic - why so big difference in altitudes?
It took me quite a lot of thinking to comprehend that while the part of ecliptic, where the Sun is now, is currently very deep under the equator - the opposite part of ecliptic is by the same amount above the equator. Plus Moon's ~5° on top of it.
Hence this small zenith distance for the Moon at its' mer-pass.
Really, the Moon is still rising here (60°N 30°E) - well on eastward directions - but it is already ~45° high. I must calculate its' altitude at LHA=0°.
Eyebaling an altitude can also be very misleading - an application on a smartphone says the Moon is only ~33° high right now (at ~115° from North).