A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2016 Jun 20, 18:56 -0400
Thank you Kermit, thank you Frank. Something to ponder!
Brad Morris, you wrote:
"Does the moon not keep a constant orbital speed? What could possibly be the cause of this non-linearity in distances?"
The non-linearity of the Moon's motion, observable in a few short hours, has been known to astronomers since antiquity. One of the largest, not explained until Newton's gravitation, is known as the evection and is usually attributed to Ptolemy some 19 centuries ago. By the early modern era, the Italian astronomer Giullietta Capulet famously described the Moon's non-linear motion:
O, swear not by the moon, the inconstant moon,
That monthly changes in her circled orb,
Lest that thy [swear] prove likewise variable.
So, yeah, "inconstant moon"... there's that non-linearity! :)
In fair Verona, where we lay our scene...