In 46 B.C. Julius Caesar did an admirable job of creating what's now known as the Julian calendar, but he was working with a piece of flawed advice. It involved the confusing business of leap years.

Because his astronomer, Sosigenes, based his calculations on an estimate of 365.25 days per solar year, Caesar figured that adding an extra day every fourth year would keep the calendar aligned with the sun. But the earth actually takes only 365.2422 days to travel around the sun, so those regularly added leap days turned out to be a few too many.

Calendar dates began to shift away from solar events, first at the almost imperceptible rate of one day in 128 years but then at an alarming three days in four centuries. By 1582, when Pope Gregory XIII addressed himself to the problem, the spring equinox was occurring on March 11 — ten full days ahead of schedule. On the advice of his astronomers, Aloysius Lilius and Christopher Clavius, Pope Gregory made two changes.

First, he dropped ten days right out of the calendar — the days between October 4 and October 15, to be exact — to realign key dates with the sun. Then he arranged to reduce the number of future leap years. He omitted them in century years except those divisible by 400. Thus, 1600 and 2000 would still be leap years, but 1700, 1800, and 1900 would not.

Some sixteenth century women were probably miffed by this change because leap years — especially February 29th itself — had become associated with the opportunity for women to ask men to marry them. The new Gregorian calendar would deprive them and their female descendants of three chances at self-selected pairings over the next five hundred years.

Recent scholars have proposed yet another modification to eliminate yet a few more leap years. They have suggested that leap years should also be omitted in years divisible by 4000 to correct a lingering discrepancy between the Gregorian calendar and solar years.

This final correction would reduce the discrepancy to only one day every 20,000 years, which maybe we should just accept. Why not declare that extra day a day-without-a-date and celebrate it as a gift from the sun?