Earth Science - Other

# Rotation Time Effects of Rotation on Time

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History held its breath between the sixth hour and the ninth hour

A person struggling on his death bed, counts every second...

If only I had more time !

People from time immemorial have been influenced by time and the effects of time. A simple word, yet the most historical of all; a small word, but the only to have lived through the ages witnessing the rise and fall of every generation, of empires being built and holding secrets to unsolved mysteries. Man's existence is calculated on the 'time' factor; his actions, his movement and the record of the stories he leaves behind him, all based on time'.

Time as we know it today is nothing but a fractional account of day, a unit of measurement to record events, and astronomically, a numerical equivalent of the motions of objects.A day is made up of twenty four hours and each hour is made up of sixty minutes. Every minute is in turn made up of sixty seconds. The calculation of time is based upon the rotation of the earth. The earth rotates in anti-clock direction, that is, from west to east and contributes to what we call day and night, based on the earth's position to the sun's view.

The ancient forms of calculating time was very simple. There was day and night, and when the sun was overhead it was simply noon. Man's biological clock would tell him when it was time to eat and when it was time to rest or work. Then the study of the shadows took over and sundials became popular. People in Egypt would calculate time based on the shadow of a particular pole or tree in their village square. Sand clocks and water clocks too became popular at a time. The main disadvantages was that the sundial could not be used at night and water / sand clocks needed to be refilled continuously. Ancient Egypt divided their day into twelve hours light and twelve hours night.

It was only during the nineteenth century, that a more scientific approach was made to determine time in different regions due to the industrial and technological growth of civilization at that time. Trains were invented and with people travelling across vast stretches of land, over a shorter period of time, a more standardised approach to time had to be adopted. In order to ease this difficulty in calculating time, Sir Sandford Fleming (1827 - 1915), in 1878, came up with the basis of what we call today as the Co-ordinated Universal Time (UTC). He divided the earth into twenty four imaginary lines called longitudes, running from north to south, and each longitude was spaced 15 degrees apart to determine an hour. It was simple to understand, and followed the similar pattern of time calculation that the Egyptians had followed, viz. twenty four hours in a day.

The longitude passing through the Royal Observatory in Greenwich, England, is marked as the Prime Meridian, (Greenwich Mean Time, GMT), and the longitude passing through the Pacific Ocean, 180 degrees away from the Prime Meridian is marked as the International Date Line. Regions ahead of the Prime Meridian have a time calculation as GMT + (n), where 'n' stands for the number of hours, and places behind the Prime Meridian are characterised as GMT - (n), that is to say, they are behind time. People travelling across the International Date Line from West to East gain a day and those travelling from East to West lose a day.

Regions like Russia and USA have many time zones as these nations pass through many longitudes, and it would also be apt to say that China, the widest nation to have just one time zone, should in fact have five. Most time zones have an hour difference between them, but among Asian countries, even half hour units of calculation are followed. More peculiar still is the time difference between India (GMT + 5:30) and Nepal (GMT + 5:45).

As in outlining a day to have twenty four hours, a month roughly has thirty one days, except in the case of April, June, September and November which have thirty days each, and twenty eight days in February. Due to the earth's slowing rotation, and to standardize calculation, every day has an additional second, that is to say, a year has a quarter of a day, and every fourth year has one day extra, the twenty ninth day of February, constituting the Leap Year. A Christian Calendar which is universally followed has months starting from January, right through to December, a Fiscal Calendar would start in April and end in March, a Solar Calendar would outline the seasons and a Lunar Calendar is based on the time span between two full moons.As is quite obvious, the measurements of time originate from light and day, which is basically the earth rotating on its axis, revolving around the sun.

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