How many hours in a day?It is known to all - 24 hours.But why did it happen?Let's take a closer look at the history of the appearance of the main units of time and find out what day, how many hours in a day, seconds and minutes.And we'll see whether these units are exclusively tied to astronomical phenomena.
Where did the day?This is the time of one revolution of the earth around its axis.Yet there is little knowledge of astronomy, people began to measure time such range, including every light and darkness.
But there is an interesting feature.When the day begins?From a modern point of view, everything is clear - a day starting at midnight.People of ancient civilizations believed otherwise.It is enough to look at the very beginning of the Bible that in the 1st book of Genesis to read: "... and there was evening and there was morning, day, one day."Day begins at sunset.This has a certain logic.In those days people were guided by daylight.The sun has set, the day ended.The evening and night - it is the next day.
But how many hours in the day?Why day divided into 24 hours, because it is more convenient decimal system, and much more?It would be in the day, say, 10 hours, and each hour 100 minutes, it would change things for us?Actually, nothing but numbers, on the contrary, it would even be more convenient to perform calculations.But the decimal system - is not the only one used in the world.
used in ancient Babylon sexagesimal counting system.And the bright half of the day is well divided in two, 6 hours each.Total in the day turned out 24 hours.It's quite convenient division took the Babylonians and other peoples.
The ancient Romans counted time there is even more interesting.Counting begins at 6 am.So we consider this moment on - the first hour, third hour.Thus, we can easily calculate that commemorates Christ "eleventh-hour workers" - those who go to work at five o'clock in the evening.Indeed, late in the day!
At six o'clock in the evening there came the twelfth hour.That's how many hours in the day numbered in ancient Rome.But it was still night!The Romans did not forget about them.After eleven o'clock began the night watches.The attendants were replaced every 3 hours at night.The evening and night was divided into four guards.The first evening the guards began at 6 pm and lasted until 9. The second, midnight, lasted from 9 to 12 hours.The third guard, from 12 am to 3 am ends when the roosters sang so called - "roosters crowing."Last, the fourth guard was called "morning" and ends at 6 am.And start all over again.
Need divided into its constituent parts and still watch arose much later, but not from the sexagesimal system and then retreated.And then the moment divided in seconds.However, later it turned out that only rely on astronomical observations to determine the duration of seconds, and the day did not.Over the length of the day increases the age at 0.0023 seconds - seems to be very little, but enough to get confused as to whether the number of seconds in a day.And that's not all the difficulties!One revolution around the Sun, our Earth does not smooth over the number of days, and it also affects the solution to the question of how many hours in a day.
Therefore, to simplify the situation does not equate to the second movement of the heavenly bodies, and by the time of the processes inside the cesium 133 atom at rest.And to match the actual state of affairs with a turnover of earth around the sun twice a year - on December 31 and June 30 - add 2 extra leap seconds and every 4 years - extra day.
Total turns out that day 24 hours or 1,440 minutes or 86,400 seconds.
