Anniversary always becomes a grandiose holiday, whether it be anniversary of the person, the city or the organization. If desired it is possible to celebrate not only traditional "round dates" – 25, 50, 100 years – but also more exotic anniversaries, for example, 10,000 hours. For this purpose it is necessary to count only a number of hours in a year.
The arithmetic calculations necessary for determination of number of hours developing in a year do not differ in complexity.
Calculation of a number of hours
Quantitative ratios of units of measure of time can seem to someone not quite convenient as they are not multiple to ten. It is explained by the fact that European civilization inherited them from Ancient Babylon where there was not the decimal numeral system habitual to the modern person, but duodecimal therefore ratios of units of time are multiple 12. Also the number of hours in day – 24 is not an exception.
To receive a number of hours in a year, it is necessary to increase only 24 on the number of the days making year. In a Gregorian calendar on which there lives the modern civilization alternate not leap-years and leap. In the first case the year contains 365 days, and in the second – 366. Multiplication of these number on 24 gives respectively to 8760 and 8784.
So, in leap year 8784 hours, and in not leap – 8760. If someone has a desire to celebrate 10,000 hour anniversary of any event, it is necessary to count of its date one year and to add 51 days if year of not leap, or 50 days if leap. For specification it would be necessary to add some more hours, but hardly someone will aspire to absolute accuracy.
Year in terms of astronomy
Duration of year established according to the calendar to some extent is conditional. It is convenient to person to begin new year together with new day. In fact Earth cycle time around the Sun which is considered year with terrestrial day does not coincide. From the point of view of the observer who is on Earth, to the beginning and end of a turn of Earth around the Sun there corresponds day of the vernal equinox. Astronomers call this period tropical year. During this time the longitude on which it is possible to observe the Sun increases by 360 degrees, passing a full circle. Tropical year which is taken into account by astronomers is slightly longer than calendar. For this reason it was necessary to enter into the calendar leap-years. Its duration is equal to 365 days 5 hours 48 minutes and 46 seconds. Therefore, by 8784 hours received earlier it is necessary to add 5 more hours and nearly 49 minutes. In this case duration of astronomical year appears to equal about 8789 hours 49 minutes and if to round, then to 8790 hours.