# Important Lines described in Geography

Equator: Keeping both the place in equal distance, an imaginary line has been drawn which encircles the globe from west to east is known as the equator. Others name of equator- 0° latitude and great circle.

Tropic of cancer and Tropic of capricorn : The 23.5° latitude in the northern and southern hemisphere are know as the Tropic of cancer and the Tropic of capricorn. The Tropic of cancer passes through the central part of Bangladesh. In the middle region of these two lines, sunshine falls on the earth perpendicularly.

Arctic circle and Antarctic circle : The 66.5° north and south latitudes are known as the Arctic and Antarctic circles (fig. 2.10).

Task : Find out the capital cities of the neighbouring countries by their latitudes and longitudes.

International Date Line

In 1884 in United States of America, an international convention regarding 'Longitude and Time' created a special longitudinal line. It identified the 180° longitudinal line as the International Date Line (fig. 2.11 ). The International Date Line is not a straight line. The longitude of 180° passes through many islands in the Pacific Ocean.

Ships or planes when they cross the International Date according to the direction Line, add or subtract a day they are travelling in. When travelling eastward, they add a day. When travelling westward, they deduct a day (fig. 2.12).

Calculations for a given meridian to find out the time and place have been explained in another article.

The International Date Line has been curved in some places. Though running along 180° east and west longitude over the Pacific ocean but to avoid the land masses of north eastern Siberia and Aleutian, Figi and Chatham islands. The International Date Line has been curved 11 ° towards the east in Aleutian, Figi and Chatham islands to avoid land masses and 12° east in the Bering Strait over the water bodies. If it was not drawn this way, the people would have to count two different local times in the same place of the island.

Task : Write about the importance of International Date Line in human life (pair work).

The antipodes: The earth is round, so it has an opposite place on the other side of the earth. From any point of the earth surface any imaginary line crossing through the centre of the earth is called the Antipode of the first point i.e. opposite side of the earth (fig. 2.13).

A certain place situated in a particular longitude is situated in the opposite longitudinal line. It means the summing up result will be 180°. As the distance between two longitudes will be 180° the time difference will be 180 x 4 = 720 minutes or 12 hours = 12 hours.

Task : Find out the antipodes of Dhaka of the globe in group.

✔ Learn about The Universe and Our Earth

✔ Learn about  Size and Shape of the World

✔ Learn about Important Lines Described in Geography

✔ Learn about The Movement of the Earth

✔ Learn about The Change of Season on Earth