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Leap Year & Leap seconds-Some Interesting Facts

 
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Dr. N. Subramanian
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PostPosted: Mon Feb 29, 2016 7:08 pm    Post subject: Leap Year & Leap seconds-Some Interesting Facts Reply with quote

A leap year, where an extra day is added to the end of February every four years, is down to the Gregorian calendar's disparity with the solar system.
A complete orbit of the earth around the sun takes exactly 365.2422 days to complete, but the Gregorian calendar uses 365 days.
So leap seconds - and leap years - are added as means of keeping our clocks (and calendars) in sync with the Earth and its seasons.

Julius Caesar vs Pope Gregory
Think thatís confusing? Up until Julius Caesar came along and created his own calendar, people observed a 355-day year with an extra month calledMercedonius. Caesar did away with that complicated system by creating a new day, which we now know as Feb. 29.
Why does the extra day fall in February?All the other months in the Julian calendar have 30 or 31 days, but February lost out to the ego of Roman Emperor Caesar Augustus.
Under his predecessor Julius Caesar, Feb had 30 days and the month named after him - July - had 31. August had only 29 days.
When Caesar Augustus became Emperor he added two days to 'his' month to make August the same as July.
So February lost out to August in the battle of the extra days.

The system was tweaked, however, about 500 years later.
As an earth year is not exactly 365.25 days long Pope Gregory XIII's astronomers decided to lose three days every 400 years when they introduced the Gregorian calendar in 1582.

The maths has worked ever since but the system will need to be rethought in about 10,000 years' time. Perhaps mankind's robot overlords will think of something.
The way the math works out, a century year is a leap year only if it is divisible by 400.  So years such as 1700, 1800 and 1900 werenít leap years. But, of course, 2016 is.
Leap day itself, Feb. 29, has long been the inspiration of folklore, most notably a tradition out of the United Kingdom of women proposing to their significant others.
Why does the woman propose on a leap year?Leap years are also marked as a time for women to propose to men.
One theory is that the custom dates back to the 5th Century, when, legend has it, an Irish nun called St Bridget complained to St Patrick that women had to wait too long for their suitors to propose. St Patrick then supposedly gave women the chance to ask the question every four years.
Women either have to wear breeches or a scarlet petticoat to pop the question, according to tradition.
In Denmark, if a man turns down a proposal they must give the woman 12 pairs of gloves and in Finland the penalty is fabric for a skirt.
Technically, a leap year isn't every four yearsThe year 2000 was a leap year, but the years 1700, 1800 and 1900 were not.
There's a leap year every year that is divisible by four, except for years that are both divisible by 100 and not divisible by 400.
The added rule about centuries (versus just every four years) was an additional fix to make up for the fact that an extra day every four years is too much of a correction.
What if you're born on February 29?The chances of having a leap birthday are one in 1,461. People who are born on February 29 are referred to as "leaplings", or "leapers". In non-leap years, many leaplings choose to celebrate their birthday on either February 28 or March 1, while purists stick to February 29 for the occasion. So, that means this year, actor Antonio Sabato Jr. will have his 11th birthday, self-help guru Tony Robbins will have his 14th and rapper Ja Rule will be celebrating his 10th.
About 4.1 million people around the world have been born on the 29th.
Pisces is the zodiac sign of a person born on February 29, and amethyst is the birthstone for this month.
What is a leap second?Leap years are not directly connected to leap seconds, but both are for the purpose of keeping the earth's rotations in line with our clocks and calendars.
Leap seconds are added to bring the earth's rotation into line with atomic time. A leap second was added at the end of June last year, when immediately before midnight dials read 11:59:60.
Atomic time is constant, but the Earthís rotation is gradually slowing down by around two thousandths of a second per day.
Leap seconds are therefore crucial to ensuring the time we use does not drift away from time based on the Earth's spin. If left unchecked, this would eventually result in clocks showing the middle of the day occurring at night.
The extra second can sometimes cause problems for some networks which rely on exact timings. When a last leap second was added in 2012 Mozilla, Reddit, Foursquare, Yelp, LinkedIn, and StumbleUpon all reported crashes and there were problems with the Linux operating system and programmes written in Java.
Facts about leap years

  1. The Summer Olympic Games are always held in a leap year. This year, they take place in Rio de Janeiro, Brazil.
  2. US presidential elections are held every four years, in a leap year.
  3. In Greece couples often avoid getting married in a leap year, believing it to be bad luck
  4. Food for thought: If you work on a fixed annual wage, today is just one more day's work than you would usually have to do for your salary.
  5. As touched on above, a year that is divisible by 100, but not by 400, is not technically a leap year. Therefore 2000 was a leap year under the Gregorian calendar, as was 1600. But 1700, 1800 and 1900 were not. "There's a good reason behind it," Ian Stewart, emeritus professor of mathematics, told the BBC. "The year is 365 days and a quarter long - but not exactly. If it was exactly, then you could say it was every four years." Pope Gregory and his astronomers' solution will have to be rethought in around 10,000 years, Prof Stewart points out.
  6. February 29 also marks Rare Disease Day.
  7. Leap years are also known as intercalary or bissextile years.
Source and see more details at: http://www.telegraph.co.uk/news/uknews/12177017/Leap-Year-2016-Why-does-February-have-29-days-every-four-years.html
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