Guwahati, Feb. 29 -- Rebecca Stephenson, University College Dublin

Have you ever wondered why the extra day of the leap year falls on February 29, an odd date in the middle of the year, and not at the end of the year on December 32? There is a simple answer, and a slightly more complex one.

Let's start with the simple answer. Several ancient cultures (including early Christians) believed the world was created in the spring and therefore March was the beginning of the year. This means that when the Roman calendar added an extra day in February, they were adding a day at the end of their year. So the simple answer is that we put the leap day at the end of February because the Romans did.

Except that isn't exactly true. The Romans did not...