# Prime Meridian Passing Through Countries

In this article,we shall look into the countries through which prime meridian passes and the significance of the same.

### Prime Meridian passes through which countries ?

Prime Meridian passes through following countries :-

1- United Kingdom( Greenwich, London)

2- France

3- Spain

4- Algeria

5- Mali

6- Burkena Faso

7- Togo

8- Ghana

### Apart from countries, through what other places Prime Meridian Passes?

1- Arctic Ocean

2- Norwegian Sea

3- Greenland Sea

4-  Mediterranean Sea

5- Atlantic Ocean

6- Southern Ocean

7- Antarctica

### What is Prime Meridian ?

Meridian are north to south lines which pass from pole to pole passing through the equator. To begin the marking of longitude, any line could be chosen as 0 degree longitude, as (unlike equator which is centrally placed), longitudes are arbitrary lines.

In 1884, it was decided by an international agreement, to choose the the zero meridian the one which passes through the Royal astronomical observatory at Greenwich, London.

Prime Meridian divides the earth into eastern and western hemisphere, as equator divides the earth into northern and southern hemisphere.

The Prime Meridian has a very important function in determining the local time with respect to the Greenwich Mean Time.

### How Local Time is calculated with respect to the Prime Meridian ?

As we know, earth makes revolution of 360 in 1 day i.e in 24 hours. If we follow simple equation of mathematics:

24 hours = 3600

1 hour =3600 / 24 is equals to 150

As we know, earth rotates from west to east, so every 15we go eastwards, local time is advanced by 1 hour. We may thus conclude that as we move eastwards to Greenwich, we gain time.

Conversely, we can also say that,

15rotation = 1 hour = 60 minutes,

so,1rotation = 60/15 = 4 minutes

Let us understand the concept with the help of an example.

If it is 10 a.m at Greenwich ( 0longitude), calculate local time on 80east ?

Now lets calculate it.

0longitude = 10 a.m

for each 1rotation, time gained = 4 minutes

so, for 80, time gained= 4* 80 = 320 minutes = 5 hrs and 20 minutes

Hence if it is 10 a.m at 00, then at 80East, it would be 5 hrs 20 minutes more than 10 a.m that is 3.20 p.m.

In the same manner if we want to calculate time at 80west, then it would be 5 hrs 20 minutes less than the time at 0longitude, i.e 4.40 a.m at 80west ( keeping all the calculations same as above).

So, we can conclude that,

 Direction from Greenwich Effect on Local Time Eastwards Gain in Time Westwards Loss in Time

### What is Standard Time and Time Zones ?

If we calculate the time according to the method discussed above, then each town in world would have a different time,(as longitudes change with distance, hence time would vary), which will lead to great Chaos in human life. Travelers travelling from one end of the country to other end have to keep changing their watches if they want to keep on their appointments.:)

To avoid these difficulties, a system of Standard time is observed by all countries. Most countries adopt their standard time from the central meridian of their countries. For e.g India has accepted the meridian of 82.5east for standard time which is 5 hrs 30 minutes ahead of Greenwich Mean Time.

The whole world has been divided into 24 standard time zones each of which differs from the next by 15in longitude. Most of the countries adhere to this division, but due to peculiar shapes and locations of some countries deviations from the standard time zones is seen.

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