On Wednesday, July 9, 1522, after a voyage of nearly three years, the tattered remnant of Magellan's fleet -- a single leaking ship and skeleton crew -- reached the harbor of Ribeira Grande in the Cape Verde Islands, tantalizingly close to home. According to the islanders, it was Thursday. The captain wrote: "We were greatly surprised for it was Wednesday with us, and we could not see how we had made a mistake; for I had always kept well, and had always set down every day without interruption." Slowly the explanation dawned: "It was no error, but as the voyage had been made continually toward the west, and we had returned to the same place as does the sun, we had made a gain of twenty-four hours."
This was a source of great amazement to the sailors (as later to Europeans in general). But it was also a source of moral consternation. By this miscalculation, they had violated their faith by eating meat on Fridays, and celebrating Easter on a Monday.
Some years ago -- 1986, to be exact -- Sky & Telescope magazine flew me out to Australia to write a piece about Halley's Comet, which promised its best apparition in southern skies. Flying home, the plane approached the international date line near midnight on Easter. A short time later it was Easter morning. I had two Easters that year. I willingly concede my extra Easter for the repose of the souls of the Magellanic circumnavigators.