Feb. 29, 2000
Poem: "John Henry" (unknown).
Today is Leap Year Day, the day our calendar realigns itself with the solar year. In 45 B.C., Julius Caesar introduced the Julian Calendarwith all the months and days we know today, including a special day added every four years at the end of February. Since the Earth takes approximately 365 ¼ days to make its revolution around the sun, it was determined (by the Greek mathematician Sosigenes) that adding one day every four years would keep the calendar and the solar year in step. Before Julius Caesar decreed this system as the official calendar of the Roman Empireeliminating dozens of others then in usethe system was so confusing that the government had a department whose sole purpose was to tell citizens what day it was. But Sosigenes' calculation of 365 ¼ days is off by about 11 minutes and 14 seconds, which may not seem like much, but over the course of hundreds of years it adds up. By the late sixteenth century, the Julian Calendar had gotten ten days ahead of the solar year, and the date of the vernal equinoxwhich determines the date of Easterwas creeping steadily forward. Pope Gregory the Thirteenth appointed the Jesuit mathematician Christopher Clavius to figure out how to get the vernal equinox back to around March 21st and how to keep it there. Clavius made three recommendations: first, to drop ten days from the year. And so, by papal decree, in 1582 there was no October 5th through 14ththey just didnít happen you went to bed the evening of the 4th and woke up the morning of the 15th. Second, since a leap day every four years added too much time, Clavius suggested skipping it during years divisible by one hundred. And third, since the last rule took away just a little too much time, he recommended putting it back in on years divisible by four hundred. So 1700, 1800, 1900 were not leap years, but 2000 is, and that is why we have today.
Be well, do good work, and keep in touch.®