Karkauspäivän

Karkauspäivän, also known as Leap Day, is an extra day added to the end of February every four years. This day is inserted to keep our calendar year synchronized with the astronomical year. The Earth's orbit around the Sun is not exactly 365 days; it takes approximately 365.2422 days. Without this adjustment, the seasons would gradually drift out of sync with the calendar.

The Gregorian calendar, which is the most widely used calendar system today, implements the leap day rule. A year is a leap year if it is divisible by four, except for end-of-century years, which must also be divisible by 400. For example, 2000 was a leap year because it was divisible by 400, but 1900 was not a leap year because it was not divisible by 400.

The addition of February 29th is a relatively simple yet crucial correction. Without it, over centuries, summer months would eventually occur in what we currently consider winter, and vice versa. The concept of a leap day has a long history, with earlier calendars also attempting to account for the fractional difference in the Earth's orbital period.

In many cultures, leap day is associated with traditions and sometimes superstitions. Historically, in some parts of the world, it was considered a time when women could propose marriage to men, reversing traditional gender roles for the day. While these traditions are not widely practiced today, the concept of karkauspäivän remains an essential component of our modern calendar system.