From the earliest times the phases of the moon have been important to seamen, and the regularity of its movements provided a means for recording the passage of time. The moon was credited with considerable influence on the weather and Virgil (70–19 bc) summarized some of the popular beliefs concerning it in one of the Georgics. According to Pliny (ad 23–79) the fourth and fifth days of new moon were to be watched with particular care. A new moon with horns erect on the fourth day was believed to forecast great storms at sea. The Venerable Bede (673–735) in his De Natura Rerum says of the moon: ‘If she looks like gold in her last quarter, there will be wind, if on top of the crescent black spots appear, it will be a rainy month, if in the middle, her full moon will be serene.’ A star-dogged moon was regarded by sailors as a bad omen, and reference to this phenomenon is to be found in an old Scottish ballad of 1281, ‘Sir Patrick Spens’, and also in Samuel Taylor Coleridge's ‘The Rime of the Ancient Mariner’. In several of his plays, Shakespeare refers to the popular beliefs concerning the moon which, in Hamlet, he describes as ‘The moist star upon whose influence Neptune's empire stands’.
While many of the superstitions of sailors regarding the moon have no grounding in scientific fact, the lunar haloes to which Varro (116–27 bc) refers as foretelling wind from the bright quarter of the circle, with a double circle indicating a violent storm, are well authenticated as precursors of bad weather.
Although the Greek mathematician and astronomer Ptolemy (c.ad 90–168) appreciated the connection between the movements of the moon and the tides, it was not until Sir Isaac Newton (1642–1727) discovered the law of gravity that this phenomenon was satisfactorily explained.
Subjects: Maritime History.