Social Studies Answer in brief

• Our 24-hour day starts at 12 midnight. Because of the earth’s rotation, the midnight occurs at different times, at different places.
• As the Earth is spherical in shape, every place has a place to its East.
• So, it was necessary to determine at what location to the East does the day start on Earth.
• Hence, representatives of many nations got together, under the leadership of an American Professor, Davidson, in the year 1884 and decided the International Date Line.
• The line was drawn opposite to the Greenwich Prime Meridian i.e. with reference to the 180° Meridian.

• If the IDL had passed through a land or some islands, the people there would have had to follow different dates and timings because dates would have been different on their Eastern and Western parts.
• Also, it would have been difficult to know when one crosses the IDL on land and when the date changes on the calendar.
• Hence, the IDL does not pass through land

• Attempt has been made to make the IDL pass through the Pacific Ocean completely.
• Had it passed through a land or some islands, the people there would have had to follow different dates and timings because dates would have been different on their Eastern and Western parts.
• Also, it would have been difficult to know when one crosses the IDL on land, and when the date changes on the calendar.
• Therefore, the IDL is not a straight line like the 1 180° Meridian. At places, it turns East while at other places, it turns West.

• When you cross the 180° meridian, some precautions need to be taken.
• There is a difference of 12 hours from Prime Meridian, if you go from East or West.
• According to the convention, the start (and end) of a date is considered to be at 180° Meridian.
• Accordingly, an adjustment or change in day and time is made. Thus, while travelling from east to west of IDL , a day is added whereas while travelling from west to east of IDL, the day remains the same.

1. The direction of travel
2. The current day and date

• • Accordingly, while traveling from East to West of IDL, a day is added. For example, while travelling from America to Japan, if it is Thursday 25th December, then it will be Friday 26th December in Japan.
  • While from West to East of IDL, the day remains the same. For example, while travelling from Japan to America, if it is Thursday 25th December, then Thursday 25th December, only should be considered.