arithmetic calculations necessary to determine the number of hours developing a year, not complicated.

## calculation of the number of hours

quantitative ratio of units of time someone can not seem entirely comfortable, because they are not multiples of ten.This is explained by the fact that European civilization had inherited them from ancient Babylon, where there is not a decimal number system, familiar to modern man, and duodecimal, so the ratio of units of multiples of 12. The time is no exception and the number of hours in the day - 24.

To get the number ofhours per year, it is necessary only 24 multiplied by the number of days that constitute a year.In the Gregorian calendar, in which moder
n civilization lives, alternate non-leap years, and leap.In the first case a year contains 365 days, while the second - 366. Multiply this number by 24 gives respectively 8760 and 8784.

So, in a leap year, 8784 hours, and in non-leap - 8760. If anyone ever have a desire to celebrate the 10000 hours anniversary of any event, it is necessary to count on its date of one year and add 51 days, if a non-leap year, or 50 days if a leap year.For more accurate should add a few more hours, but hardly anyone would aspire to absolute accuracy.

## year in terms of astronomy

installed on the duration of the calendar year, to a certain extent arbitrary.Man is convenient to begin the new year with new days.In fact, the period of revolution of the Earth around the Sun, which is the year, with the terrestrial day is not the same.

From the perspective of the observer on Earth, the beginning and the end of rotation of the Earth around the Sun corresponds to the day of the vernal equinox.Astronomers call this period the tropical year.During this time, longitude, on which one can observe the sun increases by 360 degrees, going a full circle.

tropical year, which take into account the astronomers slightly longer than the calendar.That is why it was necessary to introduce a calendar leap years.Its duration is 365 days 5 hours 48 minutes and 46 seconds.Consequently, a previously obtained 8784 hours is necessary to add a further 5 hours and about 49 minutes.In this case, the length of the astronomical year is equal to approximately 8789 hours 49 minutes and if the round, then 8790 hours.