A leap year occurs once every number of years. Why was the year called a leap year and why is an extra day needed every four years?

A leap year occurs once every four years. But why then was 1904 a leap year, 1900 was not, and 2000 was again?

The Summer Olympics are held in a leap year - where did this order come from? And why do we need any special “extended” years at all? How are they different from ordinary ones? Let's figure it out.

Who introduced leap years into the calendar?

Ancient Roman astronomers were well aware that a year on Earth lasts 365 days and a few more hours. Because of this, the calendar year, which then consisted of a constant number of days, did not coincide with the astronomical one. The excess hours gradually accumulated, turning into days. Calendar dates gradually shifted and deviated from natural phenomena such as the equinoxes. A group of astronomers led by Sosigenes, who worked at the court of Julius Caesar, proposed adjusting the calendar. According to the new chronology, every fourth year was extended by one day. This year began to be called bis sextus, which in Latin means "second sixth" . In Russian this word was transformed into "leap" - that’s what we call it to this day.

By order of Julius Caesar, a new calendar was introduced starting in 45 BC. After the death of the emperor, there was a glitch in the calculation of leap years, and the countdown began again from the 8th year of our era. That's why even years are leap years today.

It was decided to add a day to the last, shortest month of the year, which already “didn’t have enough days.” In Ancient Rome, the New Year was celebrated on March 1, so the extra 366th day was added to February. The new calendar began to be called “Julian” in honor of Caesar. By the way, the Orthodox and some other churches still live according to the Julian calendar - this is a tribute to tradition.

And again the calendar changes

Astronomical observations continued, methods became more and more accurate. Over time, astrologers realized that the duration of the earth's year is not 365 days and 6 hours, but slightly less. (We now know that a year lasts 365 days, 5 hours, 48 ​​minutes and 46 seconds.)


The use of the Julian calendar led to the fact that the calendar began to lag behind the real flow of time. Astronomers have noticed that the spring equinox occurs much earlier than the day allotted to it according to the calendar, that is, March 21. There was a need to adjust the calendar, which was done by decree of Pope Gregory XIII in 1582.

To compensate for the discrepancy, they decided to set leap years according to a new rule. It was necessary to reduce their number, which was done. From that moment on, all years that are divisible by four are still considered leap years, except those that are divisible by 100. For even more accurate calculation, years that are divisible by 400 are still considered leap years.

That is why 1900 (like 1700 and 1800) was not a leap year, but 2000 (like 1600) was.

The new calendar was named Gregorian in honor of the Pope - all countries of the world currently live according to it. The Julian calendar is used by a number of Christian churches, including the Russian Orthodox Church.

Rule for determining leap years

So, leap years are determined using a simple algorithm:

If a year is divisible by 4 but not divisible by 100, it is a leap year;

If a year is divisible by 100, it is not considered a leap year;

If a year is divisible by 100 and also divisible by 400, it is a leap year.

How is a leap year different from others?

Only one - it has 366 days, with an additional day assigned to February. Despite the fact that the year now begins on January 1, which means the last month of the year is December, we still give an extra day to February. He's the shortest - we'll feel sorry for him!

And let's rejoice for those who were born on February 29 in a leap year. These “lucky ones” celebrate their birthday once every four years, which makes this event more long-awaited and desirable than for other people.

What happens during a leap year?

Leap years were chosen to host the main sporting event of humanity - the Olympics. Now, in leap years, only the summer Games are held, and the winter Games are held with a shift of two years. The sports community adheres to the most ancient tradition, which was established by the first Olympians - the ancient Greeks.


It was they who decided that such a grandiose event should not happen too often - once every four years. The four-year cycle coincided with the alternation of leap years, so the modern Olympics began to be held in leap years.

1708
Peter issues a decree on the foundation of the Biysk fortress

1784
Leo von Klenze, the founder of architectural movements based on the principle of “new - slightly rebuilt antique”, was born. And the Marquis de Sade was transferred to the Bastille, where in five years he would write three of his most famous and shocking novels.

1792
Gioachino Rossini is born.

1812
Napoleon appoints commanders in his army. Alexander I is considering a gas lighting project in the capital of his empire.

1816
The Grand Duchess marries - of course, to the prince. The Russian emperor takes care of widows and the country's legislation.

1828
The premiere of Ober's opera “The Mute of Portici” (or “Fenella”) took place.

1832
Charles Darwin explores the Brazilian jungle during the Beagle expedition.

1856
The Crimean War is over.

1860
Herman Cholerite was born.

1880
The St. Gotthard Tunnel was completed.

1888
The Russian Empire is full of cultural events. Performances are performed, writers write letters. In Europe, Engels writes something of little interest to Liebknecht. In America, there is another round of court cases that ultimately dragged on for a quarter of a century and led to changes in the rules of judicial evidence.

1892
An international commission has been created to regulate fur seal fishing. This was one of the first examples of international cooperation in animal conservation.

1896
Talented organizers and creative personalities were born all over the world on this year and day.

1900
According to the Gregorian calendar, 1900 is a non-leap year, and according to the Julian calendar, it is a leap year.

1904
The Russo-Japanese War is one of the first in the 20th century. And in Europe they dance and sing.

1908
Liquid helium was obtained at the Leiden laboratory. The Oryol Central Center has been created in Russia. They play football in Brazil.

1912
Joseph Stalin escapes from exile. Russia helps in concluding the Serbian-Bulgarian treaty. Workers go on strike in Bodaibo.

1916
Strikes, pogroms, sunken ships, orders and everything that accompanies a world war. In Moscow, poets are self-elected to the Chairmen of the Globe.

1920
The Red Army is pushing back the atamans of Denikin and Annenkov. The first constitution was approved in the Czech Republic. The Kapp putsch began in Germany.

1924
After the civil war, culture revives. Surrogate money is prohibited. Vladimir Kryukov, chairman of the KGB and member of the State Emergency Committee, is born.

1928
The Central Election Commission and the Council of People's Commissars of all levels produce documents. Writers write letters. The artists perform. The ships are being built. Celebrities are born.

1932
There is an armed rebellion of fascists in Finland. The last emperor of China is still trying to lead the state.

1936
Niels Bohr proposed a planetary model of the structure of the atom.

1940
Hitler is fooling the American diplomat. Black Hattie McDaniel wins an Oscar.

1944
Soviet troops are successfully advancing in all directions.

1948
The President of Peru criticizes his opponents. Irina Kupchenko was born.

1952
The USSR sends notes to America because of the Katyn affair. A letter about Paulus is sent to Stalin. The Academy of Arts thinks about talented children. Aircraft testing ends and begins. Raisa Smetanina is born in the village of Mokhcha.

1956
Planes are flying. Unfairly accused and executed generals have been rehabilitated. The Islamic Republic of Pakistan was created. The President of Finland resigned. In Korea, articles are published that fully support the opinion of the country's leader.

1960
Largest earthquake in Morocco. Flights of cruise missiles and new aircraft. Film premieres. Writers and at least one serial killer were born.

1964
Launching of a Soviet nuclear submarine. A message from the Americans about the existence of a new strategic fighter aircraft. The Pact of Arab Cultural Unity is signed.

1968
Ships and submarines have been launched. The Il-18D plane crashed.

1972
V. Vysotsky sings in Moscow. In the USA, John Lennon begins to fight for an American visa.

A leap year gives rise to many superstitions and rumors, which mainly boil down to the fact that this year is unlucky and rich in negative events. Let's see if this is true.

Leap year: a little history

The word “leap year” is of Latin origin and translates as “second sixth.” According to the Julian calendar, the year lasted 365.25 days, with each day shifting by 6 hours. Such an error could confuse the ancient men; to prevent this from happening, it was decided that every fourth year would consist of 366 days, and February would become one day longer. They called this year a leap year.

In Rus', there were many legends about the appearance of leap years, each of which was considered unlucky.

Legends about the appearance of a leap year in Rus'

February 29 is also called Kasyan's Day in honor of St. Kasyan. Being a bright angel, he was seduced by the tricks of evil spirits and went over to the side of the devil. However, he later repented and prayed to the Lord for mercy. Having mercy on the traitor, God assigned an angel to him. He chained Kasyan and, by order from above, beat him in the forehead with an iron hammer for 3 years, and released him on the fourth.

According to another legend, Kasyanov's day is his name day. However, each time the saint got dead drunk for three years and came to his senses only in the fourth year. That is why he is supposed to celebrate his day so rarely.

There is a third legend: walking along the road, St. Kasyan and St. Nicholas the Wonderworker met a peasant. He asked for help because his cart was stuck in the mud. To which Kasyan replied that he was afraid to stain his robe, and Nikolai helped. The saints came to heaven, God noticed that Nicholas' robe was dirty and asked what was the matter. The Wonderworker told him what happened. Then God noticed that Kasyan’s robe was clean and asked if they weren’t walking together? Kasyan replied that he was afraid of getting his clothes dirty. God realized that the saint was being disingenuous and made it so that his name day comes once every 4 years. And Nikolai’s name day for his kindness is twice a year.

Leap years were notorious in Rus': we will not continue the list of legends for long, here is one example: honest people tried to complete all their work before February 29. Many did not dare to leave the house, the sun on this day was called “The Eye of Kasyan”, they were afraid to get under the sun, so that Kasyan would not jinx them and send them illness and suffering.

Superstitions about leap year

As in ancient times, in the modern world there are often signs and superstitions that do not characterize leap years from the best side (the list is given below):

• You need to hold off on getting married during a leap year. Such a marriage will not be durable, the young people will quarrel, and the newly created family will bring upon itself troubles and misfortunes.
• You need to put off selling, buying, exchanging real estate or building a house. Deals concluded this year will not be profitable and will inevitably lead to the ruin of the parties. But the new housing will not last long.
• Any undertaking is dangerous - changing jobs, moving, starting a business. The sign is understandable: the presence of a 29th day in one of the winter months can characterize the whole year as not being what it should be. Therefore, it is easier for a person who is unsure of his own abilities to give up something new than to make an effort to start and develop a business.
• You cannot get pregnant and give birth, as the birth will be difficult and the baby may be born unhealthy. Or his life will be hard and joyless.
• A leap year “mows down” people, that is, it takes them away. It is generally accepted that mortality increases every fourth year, although this superstition is not statistically confirmed.
• You cannot pick mushrooms, eat them or sell them to people, so as not to raise something bad from the ground.
• It is believed that leap years entail natural disasters and disasters: fires, floods, drought.

What years are leap years? List of leap years in the 20th century

In the last century, as well as in the 21st century, leap years have made superstitious people afraid. A list of them is given below:

• 1900s: -00; -04; -08; -12, and so on, every fourth year.
• The year two thousand was also a leap year.

Leap years: 21st century list

To this day, many people wait with fear for a leap year, psychologically setting themselves up for trouble and explaining the misfortunes by the presence of an extra day in February.

Leap years, list since 2000: -04; -08; -12; -16, and then every fourth year.

Instead of a conclusion

According to statistics, only a small number of all troubles and disasters occur in leap years. The superstitions that exist to this day can be explained by the fact that people, closely following the troubles and misfortunes that happened during leap years, attached exaggerated importance to what was happening solely because of the unflattering glory of the latter.

For people who believe too much in leap year superstitions, I would like to wish them to pay more attention to positive changes and events. And then, perhaps, a list of good omens will appear that will rehabilitate leap years.

I hope you had a great New Year and are in a great holiday mood right now. At least that’s how it is for me - we didn’t drink any alcohol, and clinked glasses of water from a five-liter canister at midnight, so we woke up, took a walk, and then I remembered one of yesterday’s Happy New Year greetings:

I wish that at the end of each year, remembering what happened over the last 366 if ((year%4 == 0 and year%100 != 0) or (year%400 == 0)) else 365 days, think about myself:

Oh, wow, what an action that was. I will definitely tell my grandchildren or write a book about it later.

For example, 2013 is not a leap year, 1700, 1800 and 1900 are again not leap years, but 2000, 2004, 2008 and 2012 are leap years.

But what if we don't remember how many days there are in leap years (366 days) and non-leap years (365 days), or we just want to write the definition of the number of days in a year as quickly as possible? Is it possible to do this in Python? Of course you can.

So Python has a calendar module. It is perfect for finding out whether a year is a leap year (or, for example, how many leap years there are in a certain interval), determining the number of days in a month, getting the number of the day of the week for a certain date, and so on.

In particular, we can get the number of days in each month of the year and simply add them up.

The calendar.monthrange function takes the year number as the first argument and the month number as the second argument. Returns the number of the day of the week on the first day of the given month and the number of days in the given month:

>>> import calendar >>> calendar.monthrange(2013, 1) (1, 31)
Accordingly, we can calculate the total number of days for all 12 months, and thus obtain the number of days for a given year:

>>> import calendar >>> year = 2013 >>> sum(map(lambda x: calendar.monthrange(year, x), range(1, 13))) 365
But if you think about how exactly this line is executed, it becomes obvious that this solution is very inefficient if you need to count the number of days for a large number of years.

We check using the timeit module.

To perform it 1 million times, it takes 13.69 seconds if import calendar is done once at the beginning. If import calendar is done every time then 14.49 seconds

Now let's try another option. It requires knowing how many days there are in leap and non-leap years, but it is very short:

>>> import calendar >>> year = 2013 >>> 365+calendar.isleap(year) 365
And, as you might guess, it is already much faster: 0.83 seconds, including import calendar, and 0.26 seconds if import calendar is done once at the beginning.

Let's also see how long the very first option takes, with the "manual" approach: 0.07 seconds for 2012 and 2013 and 0.12 seconds for 2000 (I think everyone understands where such a difference in speed comes from for these years).

It turns out that this is the fastest option of these three:

>>> import calendar >>> year = 2013 >>> 366 if ((year%4 == 0 and year%100 != 0) or (year%400 == 0)) else 365 365
Of course, in most cases you can use any of these options - after all, when determining the number of days in one, two, ten or a hundred years, you are unlikely to notice any difference.

Write, optimize, improve, test and measure performance - but don't forget about the readability of the source code of your programs.

Happy New Year! Good luck, happiness, joy and self-improvement in the new year.

A leap year, or it is also called the word “leap year,” causes many rumors and superstitions, which mainly boil down to the fact that this year is unhappy and promises only negative events. In this article we will talk about how fair these opinions are.

A little history

The word “leap year” came to us from the Latin language, that is, it is of ancient origin, and its literal translation sounds like “second sixth”.

According to the Julian month, the Earth goes through its circle in 365.25 days, and every year the days shifted by 6 hours. Such an error could easily confuse ancient men, and in order to avoid this, it was decided that after every fourth year another day would be added to the annual circle. Accordingly, this year will include 366 days, and they will be added in the shortest month - February, it will consist of 29 days. To distinguish it, it was called a leapfrog.

In Ancient Rus', in turn, there were many legends about the occurrence of leap seasons, and each of them, even then, was perceived as necessarily unlucky. Legends about the arrival of the new calendar and the leap year in Rus' were also reflected in the Saints. So, February 29 is dedicated to the memory of St. Kasyan, and people call it Kasyan’s Day. Several legends and apocrypha (stories that are not recognized by the church as confirmed and consistent with what we know about God) are dedicated to this day. But it sheds light on the origins of the bad reputation of leapfrogs.

According to this legend, Kasyan appears to the common people not as a man, but as an angel, and a fallen one, who was once seduced by Satan, as a result of which he fell away from God. However, later he realized how wrong he was, repented and prayed to the Creator for mercy. Taking pity on the traitor, God, before accepting him back, assigned His angel to him. The celestial being shackled Kasyan and, by order from above, beat him on the forehead with a metal hammer to bring him to his senses for 3 years, and on the fourth he freed him.

The second legend about Kasyan

According to the second legend Kasyan is a person, and Kasyanov’s day is the date of his name day. However, according to the legend, that man systematically drank himself to death for three years in a row, but on the fourth he came to his senses, repented, gave up his addiction, turned to repentance and became a saint - he acquired the Holy Spirit. Therefore, the people believed, it was appropriate for him to celebrate his day so rarely - only on February 29.

The third legend about Kasyan

This legend is dedicated to Saint Kasyan, who travels across the earth, and Nicholas the Wonderworker, well known to Christians. And then they meet a man along the way. He asked them for help because his cart was stuck in the mud. Kasyan responded to this that he was careful not to spoil his clean robe, but Nikolai, not afraid of the dirt, immediately helped. The saints returned to the Kingdom of God, and the Creator noticed that Nicholas’s robe was dirty and asked him what was causing it.

The saint told him what happened on the way. Then the Lord noticed that Kasyan’s clothes were clean and asked the question: were they really traveling together? Kasyan replied that he was afraid to stain his clothes. God realized that Cosmas was being cunning, and arranged it in such a way that his name day is celebrated once every 4 years. And Nikolai’s name day for his meekness is twice in 365 days.

Anyway , whatever it may be, the leap was recognized as bad. Therefore, the superstitious Russian people tried to somehow protect themselves from this day.

1. I tried to finish all important things before the 29th of February.
2. Some did not dare leave the house.
3. On February 29, if the sun came out, it was called Kasyan's Eye or Kasyanov's Eye. Then they tried not to get under the sun, so that the saint wouldn’t jinx them! And he did not bring suffering and illness to the poor man.

As in ancient times, in today's world there are often superstitions and signs that do not best define the leap years of the 21st century. We will list some of them:

Why is a leap year considered bad?

This attitude is quite understandable: the appearance of the 29th day in February characterizes the whole year as being different from others, and psychologically sets it apart from others. This can be important for people who are unsure of their abilities. It will be much easier for him, citing this special period, to refuse something new than to expend energy for self-development or starting some kind of business.

For the same reason, it will be easier not to get pregnant, so as not to give birth later, because there is an increased fear that the birth will be difficult, the baby may be born sick. And if not, then suddenly his life will turn out to be joyless or difficult.

Our inventive people see and the threat in the very name of the leap, saying that it “mows down” people, in other words, takes them away, leads to death. Therefore, the holiday is celebrated with caution (or, conversely, on a special scale - you never know who will die...). This is a very common belief that tries to creep into statistics. It is becoming accepted that the mortality rate increases every 4th year. At the same time, these data are in no way confirmed by the statistics themselves.

You can’t pick mushrooms either, much less eat them or sell them to people. No, not so as not to be poisoned, but so that “bad soil” does not bring “anything bad” to a person.

It is believed that the leap year entails natural disasters and all kinds of disasters: drought, floods, fires.

What years are leap years?

In the last century, as well as in the current one, such calendar periods also caused horror. A list of them can be seen in the image or found on the Internet. Also, the year 2000, the same millennium, in turn was a leap year, opening the whole millennium.

Despite the fact that with the development of technology, information has become more accessible and it is possible to learn more and expand one’s horizons, getting rid of primitive fears, many continue to anxiously await the leap, internally preparing themselves for problems and troubles, and when they come (if they come), it is perceived as doomed: well, it’s a leap year... An extra day in February. Deadly!

There are special calendars that indicate when exactly the leap year occurs. It is enough to look carefully at the table and find (or not find) the current figures there. It is enough to know at least one leap year, after which you can calculate them yourself using elementary arithmetic. Let's say you're interested in leap years in the 21st century. Find the calendar and view it. Having learned that 2016 is a leap year, it is easy to understand that the next year will come in 2020.

If you trust statistics, a very small number of all disasters and troubles occur on leap years. The superstitions that exist today can be interpreted by the fact that people who closely followed the misfortunes and troubles that occurred during leap years gave an exaggerated meaning to what was happening only because of the unflattering reputation of the latter. I would like to wish people who highly trust superstitions about leap years to pay more attention to positive events and changes. And then, perhaps, a list of good and joyful signs will be collected that will restore the reputation of the Leap Years.