Grade 8 Geography : Uniqueness of the Earth - Part 4

Hi everyone! We have discussed about our home planet Earth and we shall now have a glance at the rotation and the way it leads to the occurrence of day and night and determination of time in different locations on the earth. We know that the earth has an axial tilt of 23.50 and its movement around its axis is named as the rotation of the earth. Moreover, sun rises on the east and sets on the west and this phenomena happens owing to the fact that the earth rotates from west to east. Due to rotation, one half of the globe gets sun light while the other half is in the dark and this is how the occurrence of day and night takes place on the earth. Sun rise occurs earlier in the countries on the east than in those on the west. 

 

 

The earth takes 23 hours and 56 minutes to complete one rotation and we call 24 hours; an earth day. Rotation of the earth has also led to the birth of regional differences in time on earth. For this, the position of longitudes on the globe is used to determine the time zones. For an instance, on a specific longitude on the globe, if it is 12 midnight, the time on its opposite longitude will be 12 noon and it means that the sun is positioned above that longitude. When earth completes one rotation, it means that as a sphere, it has moved 3600   in a day (24 hours). That is it moves 150 of longitude in one hour (60 minutes) where to move 10 of longitude, it takes 4 minutes. This portrays the time difference between two longitudes is 4 minutes. There are 24 time zones and these have been formed based on the position of longitudes. The time zones have been introduced in order to follow a standard timeline that is internationally accepted. Every time zone has a specific standard time. However, if countries spread over a large area, the standard time in different areas will vary according to their location in specific time zones.

 

This can be observed in countries like Russia, USA, Australia and etc. 

 

 

 

 

 

 

 

by Mekhala Egodawele

Photo source : Internet