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the purpose of calculation of time globally. It has of India. Thus, if it is 5.30 p.m. in India, it should
been mutually agreed by nations of the world to be 5 p.m. in Pakistan and 6 p.m. in Bangladesh.
age only 24 time for other time zones. Within the The Indian Standard Time applies for the whole
time zone, each country has its own central country. Large countries like Russia, USA and
meridian. This time is taken as the standard time Canada have more than one standard time. At
for the entire region tor the country. In India 180° longitude East or West, there is full 24
82°30 E is adopted as the standard meridian. hours’ time difference with respect to GMT.
The time at this meridian calculated with respect International Date Line is an internationally
to GMT is called Indian Standard Time (IST) agreed time change line drawn approximately
which is adopted for the whole country. The along the 180° meridian but deviating to both W
82°30' E meridian will have time difference of and E to avoid land areas in the Pacific Ocean.
5½ hours with respect to GMT (82½ x 4 min- On crossing this line, while going eastward, a day
utes = 330 minutes = 5½ hours). Being in the is added and towards the west a day is sub-
East time will be ahead of GMT by 5½ hours. If it tracted. International Date Line bends at the
is 12 noon at London, it will be 5.30 p.m. in Bering Strait between Siberia and Alaska and at
India. Two immediate neighbours of India, Fiji and Tango Islands to allow these small
Pakistan in the West and Bangladesh in the East countries to have one single time zone. Thus,
have their own Standard Time each. Pakistan standard Time is the time based on central
Standard Time is ½ hour behind that of India meridian prevailing in the particular time zone.
and Bangladesh Standard Time is ½ hour ahead

Terminology

Latitudes : the angular distance of a place north or south of the earth’s equator
Longitudes : the angular distance of a place east or west of the Greenwich meridian

Inside Story
Inside Story
g A globe is a true model of the earth in a very compact form.
g An equator is an imaginary line around the middle of a planet or other celestial bodies.

g The distance around the earth at the Equator, its circumference, is 40,075 kilometers
(24,901miles).
g To divide the earth into the Northern Hemisphere and the Southern Hemisphere, the
Equator is drawn as a circle running around the earth exactly half way between the poles.
g The torrid zone refers to the area of the earth near the equator. Parallels of latitudes and
meridians of longitudes can also be drawn on flat surface like maps.
g The earth rotates from west to east, so every 15° we go eastwards, local time is advanced
by 1 hour.
g The local time of a place is the time fixed with respect to the apparent movement of the
sun.

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