A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2016 May 6, 01:27 -0400
In particular, Jupiter's moons were used to determine longitude on land in a famous survey of France, in which the King of France complained that the surveyors caused his kingdom to shrink. Meaning that prior to the survey, the King thought his kingdom larger due to inaccurate longitudes.
Is there now and/or has there ever been a practical use (as a hobbyist or seagoer) for observing the moons of any planet as a means in the determination of one's position on earth; and, if so, how were/are those moons observable much less identifiable given typical optical means available to the sailor? Were the moons useful in determining time only and then, with that information, using other astronomical conditions to establish one's position?