In Denmark, the tradition is that women may propose on the bissextile leap day, February 24, and that refusal must be compensated with 12 pairs of gloves.
In Finland, the tradition is that if a man refuses a woman’s proposal on leap day, he should buy her the fabrics for a skirt.
In Greece, marriage in a leap year is considered unlucky. One in five engaged couples in Greece will plan to avoid getting married in a leap year.
FYI News asked David Kieda, professor of physics and chair of the Department of Physics and Astronomy, to give us some insight on why a leap year has been integrated into our calendar.
FYI News: Why do we have leap year?
David Kieda: The leap year is in place so that common astronomical events occur on the same calendar day every year (or close to it). The important events are the summer and winter solstices and the spring and fall equinoxes. This would be easy if the time for the Earth to complete one orbit was an exact number of days. Unfortunately, it is not; one exact orbit around the sun takes 365 days, five hours, 49 minutes and 12 seconds which is 365.2425 days (incidentally, this can happen; Mercury’s orbital period and rotational period is locked in a 2:3 resonance, meaning it has exactly three days for exactly two orbits around the sun!)
FYI: What effect does that extra time have on Earth?
Kieda: So the consequence for Earth is that after four orbits (years), 1490.97 days have passed. We account for that extra 0.96 by adding one leap day every four years in order to keep the solstices and equinoxes occurring on the same calendar date each year.
FYI: What would happen if we didn’t add that extra day?
Kieda: If you did not do this, then after 400 years the summer solstice would be occurring about 100 days earlier in the calendar: the calendar would say spring, when in fact it was actually summer outside.
By the way, notice the calendar still isn’t perfect…every four years you are 0.03 days short. After a century (25 leap years) you will be short by 0.75 days. So to make up for this, on the year of the century (years 1700, 1800, 1900, 2100, 2200) there is no leap day (I’ll bet you did not know that!).
Every century you are now going forward by 0.25 days. So every 400 years, you need to have an extra day. So there is a century rule: The century years do not have a leap day, unless they are divisible by 400, in which case there is a leap day.
Which explains why there was a leap day in the year 2000…the first one in 400 years!