180° longitude is called:

The correct answer is the International Date Line.

Key Points

• The International Date Line (IDL) is an imaginary line on Earth's surface defining the boundary between one day and the next.

• The 180° meridian was selected as the International Date Line because it mostly runs through the sparsely populated Central Pacific Ocean.

• It was decided at the International Meridian Conference in 1884 in Washington, D.C. where 26 countries attended.

Important Points

• The International Date Line is located halfway around the world from the Prime Meridian (0° Longitude) or about 180° east (or west) of Greenwich, London, UK, the reference point of time zones.
• It is also known as the line of demarcation.
• The Date Line runs from the North Pole to the South Pole and marks the divide between the Western and Eastern Hemisphere.
• It is not straight but zigzags to avoid political and country borders.
• When you cross the International Date Line from west to east, you subtract a day, and if you cross the line from east to west, you add a day.
• The Date Line is not defined by international law.
• Countries are free to choose the date and time zone that they want to observe.​

Mistake Points

• Don't get confused between prime meridian (0o) and international date line (180o) they are different from each other.