A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2017 Dec 12, 13:10 -0800
Another visual test to play around with: Look at the Moon's terminator and its "horns". If the horns of the Moon are aligned vertically, then the lunar necessarily leaves the Moon horizontally on its way to the Sun and nearly so for any other star or planet reasonably close to the ecliptic. Otherwise, picture a line through the horns and then aim 90° away, left or right, depending on whether it's a Near or Far limb sight. For Near Limb sights (always for the Sun!), if the center of the illuminated edge of the Moon points down, then the lunar arc is descending as it leaves the Moon, and a descending lunar arc implies that the clearing process increases the distance.