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.
