Leap Day 411

 Leap Day Information

A person only has a 1 in 1500 chance of being born on Leap Day.

Leap Years are needed to keep our calendar in alignment with the Earth's revolutions around the sun. It takes the Earth approximately 365.242199 days (a tropical year) to circle once around the Sun. If we didn't add a day on February 29 nearly every 4 years, we would lose almost six hours every year. After only 100 years, our calendar would be off by approximately 24 days!

The ancient Roman Calendar added an extra month every few years to maintain the correct seasonal changes. But Julius Caesar implemented a new calendar – the Julian Calendar – in 45 BCE (Before Common Era) with an extra day added every 4 years. At the time, Leap Day was February 24, because February was the last month of the year.

In 1582 Pope Gregory XIII refined the Julian calendar with a new rule that a century year is not a Leap Year unless it is evenly divisible by 400. This transition to the Gregorian Calendar was observed in some countries including Italy, Poland, Portugal, and Spain. The transition took longer for other countries; Great Britain started using the Gregorian Calendar in 1752 and Lithuania in 1915.

This happens every 4 years unless it is a century year that can not be divided by 400 evenly. This means that 2000 and 2400 are leap years, while 1800, 1900, 2100, 2200, 2300 and 2500 are NOT leap years.

Record Holders:

A Norwegian family named Henriksen from Andenes holds the official record of number of children born on February 29. Mrs. Karin Henriksen gave birth to 3 children on consecutive February 29; her daughter Heidi in 1960 and her sons Olav and Leif-Martin in 1964 and 1968 respectively.

According to the Guinness Book of Records, the only verified example of a family producing three consecutive generations born on February 29 is that of the Keogh family. Peter Anthony was born in Ireland on February 29, 1940, while his son Peter Eric was born on the Leap Day in the United Kingdom (UK) in 1964. His daughter, Bethany Wealth, was, in turn, born in the UK on February 29, 1996.

Famous people who were born on Leap Day: 1916 – Dinah Shore, American singer, 1924 – Al Rosen, American baseball player, 1924 – Carlos Humberto Romero, former president of El Salvador, 1960 – Anthony (Tony) Robbins, American motivational speaker, 1964 – Lyndon Byers, Canadian hockey player, 1972 – Antonio Sabàto Jr, Italian-born actor, 1976 – Ja Rule, American rapper and actor, 1980 – Chris Conley, American musician and songwriter/composer

The Leap Second

Leap seconds have been added to atomic clocks since 1972. timeanddate.com examines in this article what a leap second is, why it is used and why the Earth is slowing down.

What is a Leap Second?:

A leap second is a second, as measured by an atomic clock, added to or subtracted from Coordinated Universal Time (UTC) to make it agree with astronomical time to within 0.9 second. It compensates for slowing in the Earth’s rotation and is added during the end of June or December. The first leap second was added to atomic clocks in 1972. To understand the concept of a leap second, we need to look at how seconds are used.

The second is the base unit for modern time keeping. The second was previously defined based on the Earth's rotation, but because modern atomic clocks are more accurate than the Earth's rotation the definition was changed in 1967. A second is currently defined as being the duration of 9,192,631,770 periods/oscillations of radiation from a Cesium-133 atom at the ground state. This is where ground state refers to a cesium (or caesium) atom at rest at a temperature of 0 K (kelvin) (coldest possible). It is also possible to have a negative leap second, where one second is removed, in a case where the Earth is rotating faster, but such a negative second has never been used, and is rather unlikely to be used in the future.

Leap seconds are added to keep the atomic clocks synchronized with the Earth's rotation. This is because the Earth rotates at a slower pace over time while the atomic clocks do not slow down. On one average day the difference between atomic clocks and Earth's rotation is around 0.002 seconds, or around 1 second every 1.5 years.

The time to do one rotation differs from day to day and from year to year. The Earth was slower than atomic clocks by: 0.16 seconds in 2005; 0.30 seconds in 2006; 0.31 seconds in 2007; and 0.32 seconds in 2008. It was only 0.02 seconds slower in 2001 (based on data from IERS). The atomic clocks are occasionally instructed to add an extra second, known as the leap second, to synchronize the atomic clocks with the Earth's observed rotation. Leap seconds are inserted so that the difference between the UTC (Coordinated Universal Time) and UT1 (mean solar time - observed Earth rotation) is kept below 0.9 seconds. Therefore, the leap second adjusts the clocks to ensure that civil time (used by clocks) is as close as possible to mean solar time (the mean sun’s hour angle).

The Earth's rotation is variable but is gradually slowing down therefore the days get longer by about two thousandths of a second every century, according to Dr Bruce Warrington, from Australia’s National Measurement Institute (NMI). The most accurate and stable time comes from atomic clocks but for navigation and astronomy purposes, atomic time is synchronized with the Earth’s rotation.

Why is the Earth Slowing Down?

According to Donald L Hamilton, author of “The Mind of Mankind” (cited in “On second thought” in the Cape May County Herald), the Earth loses its kinetic energy due to all forms of friction acting on it; tides, galactic space dust, solar wind, space weather, and geo-magnetic storms. “While the rotation has slowed a seemingly insignificant amount, it has caused mountains to rise, earthquakes to occur, volcanoes to erupt and the Earth’s vast mountain ranges to rise,” Hamilton said. He believed that the earthquake that caused the devastating tsunami in south-east Asia in 2004 was another “minor” adjustment that the planet had to make. It has made millions of these adjustments over its lifetime.

February 30 was a real date

February 30 was a real date at one point in time in Sweden and the Soviet Union. However, the introduction of this date was temporary. In Sweden, February 30 resulted from an error with calendar conversion in the 18th century. About two centuries later, the Soviet revolutionary calendar featured February 30 as a result of an attempt to cut seven-day weeks into five-day weeks and to introduce 30-day months for every working month.

Sweden’s 30 days of February

In 1700 Sweden, which included Finland at the time, planned to convert from the Julian calendar to the Gregorian calendar. Therefore 1700, which should have been a leap year in the Julian calendar, was not a leap year in Sweden. However, 1704 and 1708 became leap years by error. This left Sweden out of synchronization with both the Julian and the Gregorian calendars, so the country reverted back to the Julian calendar.

February 30, 1712, came into existence in Sweden when the Julian calendar was restored and 2 leap days were added that year. Sweden’s final conversion to the Gregorian calendar occurred in 1753, when a 10-day correction was applied so that February 17 became March 1 that year. Not everyone was pleased with the calendar reform. They believed it stole 11 days of their lives.

The Soviet revolutionary calendar

February 30 existed from 1930-1931 after the Soviet Union introduced a revolutionary calendar in 1929. This calendar featured five-day weeks, 30-day months for every working month, and the remaining five or six days were “monthless” holidays. The abolition of the seven-day week in favor of a five-day week was intended to improve industrial efficiency by avoiding the regular interruption of a non-working day.

However, the Gregorian calendar continued to be used in the Soviet Union during this period. This is confirmed by successive dates found in daily issues of Pravda, the official newspaper of the Communist Party, in which February had 28 days in 1930 and 1931, in accordance with the Gregorian calendar. The Soviet revolutionary calendar was discarded as it was difficult to eliminate the Sunday rest tradition. The original seven-day week was restored in 1940.

Fact or fiction: the Julian calendar

The 13th century scholar Johannes de Sacrobosco claimed that February had 30 days in leap years between 45 BCE and 8 BCE in the Julian calendar, when February was shortened to give the month of August the same length as the month of July. However, historical evidence relating to the Julian calendar refutes Sacrobosco, who was critical of that particular calendar.