All life on Earth is determined by the proximity to the Sun and the movement of the planet around it and around its own axis. A year is the time during which our planet flies around the Sun, and a day is the time of a complete revolution around its axis. Of course, it’s very convenient for people to plan their affairs weekly, to count a certain number of days in a month or a year.
Nature is not a machine
But it turns out that for a complete revolution around the Sun, the Earth does not turn around its axis a full number of times. That is, in a year an incomplete number of days. Everyone knows that this happens 365 times and this corresponds to the number of days in a year. In fact - a little more: 365, 25, that is, an extra 6 hours runs in a year, and to be completely accurate, then an extra 5 hours, 48 minutes and 14 seconds.
Naturally, if this time is not taken into account, then the clock will turn out per day, those in months and after several hundred years, the difference between the generally accepted and astronomical calendar will be several months. For social life, this is completely unacceptable: all holidays, memorable dates will move.
Similar difficulties were discovered a long time ago, even under the Roman emperors, or rather, under one of the greatest of them - Gaia Julius Caesar.
Caesar's Order
Emperors in ancient Rome were venerated on a par with the gods, had unlimited power, so they just redid the calendar with one decree, and that’s all.
In ancient Rome, the whole year was built on the basis of the celebration of calends, non and id (so-called parts of the month). At the same time , February was considered the last month of the year . Thus, in the leap year there were 366 days, with an additional day in the last month.
After all, it was logical to add a day in the last month of the year, in February. And, interestingly, not the last day was added, as it is now, but an additional day before the calendars of the month of March. Thus, in February, it became two twenty-fourth numbers. Leap years were appointed after three years, and the first of them happened during the life of Caesar Gaius Julius. After his death, the system went astray a bit, because the priests were mistaken in their calculations, but over time, the correct leap-year calendar was restored.
Now leap years are considered a little more complicated. And this is due to those few extra minutes that are obtained with the introduction of a full additional day every four years.
New calendar
The Gregorian calendar, according to which secular society currently lives, was introduced by Pope Gregory at the end of the 16th century. The reason the new calendar was introduced is because the previous countdown was inaccurate. Adding a day every four years, the Roman ruler did not take into account that so the official calendar will be ahead of the generally accepted by 11 minutes and 46 seconds every four years.
At the time of the introduction of the new calendar, the inaccuracy of the Julian was 10 days, over time it has increased and is now 14 days. The difference increases every century by about a day. It is especially noticeable on the day of the summer and winter solstice. And since some holidays are counted from these dates, we noticed the difference.
The calendar of leap years in Gregorian numeration is a bit more complicated than in Julian.
Gregorian calendar structure
The Gregorian calendar takes into account the difference in the official and astronomical calendar of 5 hours, 48 minutes and 14 seconds, that is, every 100 years, one leap year is canceled.
So how do you know which year is a leap year and which is not? Is there a system and algorithm in canceling an extra day? Or is it better to use a list of leap years?
For convenience, such an algorithm is indeed introduced. In general, every fourth year is considered a leap year, for convenience, multiples of four are used. Therefore, if you need to find out if the leap year of your grandmother’s birth or the beginning of World War II was a leap year, you just need to find out if this year is divisible by 4 or not. Thus, the 1904th is a leap, the 1908th also, and the 1917th not.
A leap year is canceled by a change of centuries, that is, a year that is a multiple of 100. Thus, 1900 was not a leap year because it is a multiple of 100, non-leap years are also the 1800th and 1700th. But the extra day does not run over in a century, but in about 123 years, that is, amendments must again be made. How to understand which year is a leap year? If the year is a multiple of 100 and a multiple of 400, it is considered a leap year. That is, 2000 was a leap year, as was the year 1600.
The Gregorian calendar with such complex corrections is so accurate that extra time remains, but it's about seconds. Such seconds are also called leap seconds, so that it is immediately clear what it is about. There are two of them in a year and they are added on June 30 and December 31 at 23:59:59. These two seconds equalize astronomical and universal time.
How is a leap year different?
A leap year is longer than usual by one day, it has 366 days. Previously, back in Roman times, this year was two days on February 24, but now, of course, dates are considered differently. This year in February, one day more than usual, that is 29.
But it is believed that the years in which there is February 29 are miserable. There is a belief that in leap years the mortality rate rises, various misfortunes happen.
Happy or unhappy?
If you look at the mortality chart in the USSR in the second half of the 20th century and in Russia, you can see that the highest level was noted in 2000. This can be explained by economic crises, low living standards and other problems. Yes, the two thousandth was a leap (since it is divided by 400), but is this the rule? 1996 was not a record for deaths at all; in the previous 1995, mortality was higher.
In almost half a century, this indicator reached its minimum mark in 1987. The year is not a leap year, but in 1986 the mortality rate was also low, much lower than, for example, in 1981.
There are many more examples, but it is already clearly visible that mortality in the “long” years does not increase.
If you look at the birth statistics, then a clear relationship with the length of the year, too, can not be found. The leap years of the 20th century did not confirm the theory of misfortunes. The birth rate in Russia and in European countries is falling evenly. A slight rise is observed only in 1987, and then the birth rate begins to grow steadily after 2008.
Maybe a leap year determines some kind of tension in politics or predetermines natural disasters or wars?
Among the dates of the outbreak of hostilities, only one leap year can be found: 1812 — the war with Napoleon. For Russia, it ended quite happily, but, of course, in itself was a serious test. But neither the year of the revolution of 1905, nor 1917 were a leap year. The year the beginning of World War II (1939) was certainly the most unfortunate year for all of Europe, but it was not a leap year.
In leap years, earthquakes occurred in Armenia and the explosion of a hydrogen bomb, but events such as the Chernobyl disaster, the tragedy in the Japanese cities of Hiroshima and Nagasaki, the eruption of volcanoes and other disasters occurred in the most ordinary years. The list of leap years in the 20th century does not at all coincide with the mournful list of misfortunes and catastrophes.
Causes of misfortune
Psychologists believe that all statements about the fatalities of a leap year are nothing more than superstition. If it is confirmed, they talk about it. And if not confirmed, they simply forget about it. But the expectation of misfortune in itself can be a disaster. No wonder often what happens to a person is what he fears.
One of the saints said: "If you do not believe in signs, they will not be fulfilled." In this case, this is most welcome.
Jewish year in a leap year
The traditional Hebrew calendar uses the lunar months, which last 28 days. As a result, the calendar year in this system is 11 days behind the astronomical one. For adjustment, an additional month in the year is regularly introduced. A leap year in a traditional Jewish calendar consists of thirteen months.
A leap year for Jews is more common: out of nineteen, only twelve are common, and another seven are leap years. That is, the leap years of the Jews are much longer than in the usual case. But of course, we are talking only about the traditional Jewish calendar, and not about the way in which the modern state of Israel lives.
Leap year: when next
All our contemporaries will no longer be faced with exceptions in the leap years account. The next year, which will not be a leap year, is expected only in 2100, it is hardly relevant for us. So the next leap year can be calculated very simply: the next year, which is divided by 4.
2012 was a leap year, 2016 will also be a leap year, the 2020th and 2024th, 2028th and 2032th will become leap. Calculating this is easy. Of course, it is necessary to know this, but let this information not be scary. And in a leap year, wonderful and joyful events happen. For example, people born on February 29th are considered lucky and happy.