- - calendar,
- - Watch
Now, as before, the basic unit of timing are per day, which is equal to one cycle of rotation of the Earth aroundits axis.Once they were arbitrarily divided into 24 hours, an hour - 60 minutes, a minute - 60 seconds.Now, in order to determine how much time is enough to look at the clock.Mechanical or electronic, being properly and in time reconciled, they will show you the exact time .
However, day - not much time unit.Watching the change of phases of the moon, people have found that the length of the month - 28 days.And, despite the fact that the count was not qu
ite accurate, we still use the values produced by this unit of time - a week, consisting of 7 days.
Since the division of the year into months in our calendar is quite arbitrary, different months have different numbers of days - from 28 to 31. Year - value is also not very accurate.We live by the calendar, in which three of the four years are 365 days, and the fourth, because of an error, - 366.
Not so long ago in our country have been taken, such as the timing unit five-year planand a decade.Currently time they are used much less often, however, these values can be found in the pages of history textbooks, which tells about the events of the twentieth century.
also in the history books you can find such values as the century, century and millennium.These time intervals can be divided human civilization, which has just a few thousand years.Speaking of human century, it means 70-80 years.And talking about the age of our planet and stars, such values should be used as the millions and billions of years.