Which Way Did They Go?

The survivors of Magellan’s circumnavigation of the world were perplexed upon returning to Spain to discover that their actual day of arrival was Sunday, September 7, 1522, when they thought it was Saturday. Phileas Fogg in “Around the World in Eighty Days,” was arrested and prevented from collecting his bet upon his return on what he perceived was the 80th day. The next day much to his surprise, he was informed it was the actual 80th day and he won his bet. Explain the phenomenon both voyages encountered as well as which direction these voyages took.

a. Magellan’s crew traveled westward and Fogg traveled eastward
b. Magellan’s crew traveled eastward and Fogg traveled westward
c. Both voyagers traveled eastward, but Magellan’s crew used the Julian calendar and Fogg used the Gregorian calendar
d. Both voyagers traveled westward, but used inaccurate time sources

The answer is:
To solve this question you must know that the Earth rotates from West to East. Magellan’s crew, by sailing westward, experienced longer days traveling in the opposite direction of the Earth’s rotation and counted one less sunrise in the course of their journey. They had to gain a day in their travels. Fogg, by journeying eastward in the same direction of the rotation of the Earth, experienced shortened days counting one extra sunrise in his travels. He had to lose a day. In each case, the journey was either lengthened or shortened by one day as the circumnavigation effectively was equivalent to one rotation of the Earth. If the circumnavigation was westward (opposite to the rotation of the Earth), the voyagers would perceive (wrongly) that the trip was shorter by one day. If the circumnavigation was eastward (in the same direction of the rotation of the Earth), the voyager would perceive (wrongly) that the trip was longer by one day. Thus, we have the convention when crossing the International Date Line that going west we gain a day and going east we lose a day.

Magellan Sailing Westward