local time, standard time and international date line
LESSON 6: LOCAL TIME
This is the time of the day at a given longitude determining by the movement of the sun from east to west. It is also called SUN TIME
Places on different longitude hence have different local time. The is a different of 4MINS for every one degree of longitudes E.G If it is 12:00am on longitude 5° what will be the time on longitude 6°? It will be 12:04 am.
If this sun time is used, places in the same country will have different time. This will cause more confusion. In order to avoid this confusion, a special time has been design for use called STANDARD TIME
LESSON 7: STANDARD TIME
The globe is made up of 360°; since the earth is round this implies that there are 360 lines of longitudes. These lines have been divided into groups of 15 longitudes each. That is 15, 30, 45, up to 180 east and west of the Greenwich meridian. Each of these groups of 15 longitudes is called TIME ZONE. Because of this division we have in total 24 TIME ZONES
Each of these times zones of 15 longitudes represent 1HOUR because
- 1°=4minutes
- Hence 4minutes *15 longitudes =1 hour
Thus the different in time from one time zone to the next is 1 hour
All places belonging to the same time zone have the same time. This time attributed to a time zone is called STANDARD TIME
LESSON 8: THE INTERNATIONAL DATE LINE (IDL)
The IDL is a line that when one crosses he either gains or loses a day. This line is the 180° east and west. Crossing the date line from west to east a day is lost and crossing it from east to west a day is gain E.G a traveller moving from the United State of America(in the west ) to japan (in the east) loses a day. If the traveller leave the USA at 5:00 am on Monday 25 December and crosses the IDL , he would arrive Japan at 5:00 am on Tuesday 26 December. This mean that he would lose a day.The American traveller on departing that Monday would not spend Christmas holiday and on arriving Japan at 5:00 am on the Tuesday 26 December, would discover that Christmas had been celebrated a day earlier. Therefore, he would lose a day by note celebrating Christmas.
On the other hand, another traveller from Japan crossing the IDL at 5:00 am on Tuesday 26 December would arrive USA at 5:00 am on Monday 25 December. This traveller will gain a day because he would have to celebrate Christmas in America for the second time.
