walknote.eu.org - We have already entered the year 2024 for almost two weeks. This year is considered special not only because of the upcoming presidential election but also because it is a leap year.
A leap year occurs once every four years, marked by the addition of an extra day in the month of February.
But what exactly is a leap year, and why does it exist?
Leap Year Defined
Quoting Live Science on Tuesday (1/9/2024), a leap year is a calendar year with 366 days, not the typical 365 days.
Leap years occur every fourth year in the Gregorian calendar or the calendar used by most of the world. The additional day, known as the leap day, falls on February 29 and is not present in non-leap years.
Every year divisible by four, such as 2020 and 2024, is a leap year, except for years ending in 00, like 1900. The term "leap year" originates from the fact that starting from March onwards, each date in a leap year advances one additional day from the previous year.
For example, if March 1, 2023, is a Wednesday, in 2024, it falls on a Friday.
Other calendars, including the Hebrew, Islamic, Chinese, and Ethiopian calendars, also have versions of leap years. However, these leap years do not always occur every four years and often differ from leap years in the Gregorian calendar.
In addition to leap years and leap days, the Gregorian calendar also incorporates occasional leap seconds, last added in 2012, 2015, and 2016. Nevertheless, the International Bureau of Weights and Measures (IBWM), the organization responsible for global time accuracy, plans to eliminate leap seconds starting from 2035 onwards.
Why Do We Need Leap Years?
Leap years are crucial because without them, the calendar would gradually drift out of sync with the solar year.
Leap years exist because one year in the Gregorian calendar is slightly shorter than the solar or tropical year—the time it takes for Earth to orbit the Sun once fully.
A calendar year comprises 365 days, whereas a solar year is approximately 365.24 days, or 365 days, 5 hours, 48 minutes, and 56 seconds.
If the difference is not taken into account, with each passing year, the gap between the calendar year and the solar year would accumulate by 5 hours, 48 minutes, and 56 seconds.
Over time, this would lead to a shift in the occurrence of seasons. For instance, if we were to cease using leap years, in about 700 years, the summer in the northern hemisphere would commence in December instead of June.
Adding a leap day every fourth year helps alleviate most of these issues because the added day's length is roughly equivalent to the accumulated difference over that period.
However, this system is not perfect. We gain approximately an extra 44 minutes every four years, or one day every 129 years. To address this, we skip a leap year every century, except for years divisible by 400, such as 1600 and 2000. Nevertheless, there is still a small discrepancy between the calendar year and the solar year.
Overall, leap years ensure that the Gregorian calendar remains in sync with our journey around the Sun. (wp)
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