Grade 8 Geography : Uniqueness of the Earth - Part 5
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Grade 8 Geography : Uniqueness of the Earth - Part 5

Grade 8 Geography : Uniqueness of the Earth - Part 5

Have you heard about the International Date Line?

 

We learnt that the Greenwich Meridian Line is the 00 longitude that extends from the North Pole to the South Pole, through the Greenwich, London in England. This longitude is considered as the “line of demarcation” as well. The fact that it takes one hour to move a 150 of longitude was discussed in the previous article. If we consider 150 longitude from the Greenwich Meridian towards the east, we add one hour to the time on 00 longitude whereas if we take 150 longitude towards its west, we will reduce one hour from the same. The International Date Line is an imaginary line drawn approximately on the opposite side of the globe from the Greenwich Meridian Line.

 

 

When the International Date Line is considered, it is positioned based on the 1800 longitude where the either sides of this line portray a difference of one day (approx.24 hours). Hence, when the International Date Line is being crossed, the time on clocks must be adjusted accordingly. That is, when we cross the line while moving towards the west, we must add one day (24 hours). On the contrary, if we cross it and move towards the east, it happens vice versa. Moreover, this is drawn by avoiding the boundaries of some countries in order to overcome the issues that may rise by drawing the date line along the 1800 longitude. Therefore, it is not a straight line and it is used to separate two consecutive days from each other on a calendar. For an instance, when the time on the 00 longitude (Greenwich Meridian Line), that is at the Greenwich, England   is 12 p.m. (noon) on a Saturday, it should be noted the time in Sri Lanka that is located to its east will be 5.30 p.m.(Saturday). Similarly, it will be 6 a.m. at Texas in the USA. At the same time, the time on the International Date Line will be 12a.m. (midnight).

 

 

 

 

 

 

 

by Mekhala Egodawele

 Photo source : Internet

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