GENERAL KNOWLEDGE

Detailed explanation-1: -Longitude is measured by imaginary lines that run around Earth vertically (up and down) and meet at the North and South Poles. These lines are known as meridians.

Detailed explanation-2: -Meridians of Longitude. Meridians of longitude are imaginary half-circles running from the North Pole to the South Pole. They are sometimes called lines of longitude.

Detailed explanation-3: -Greenwich meridian, also called prime meridian, an imaginary line, last established in 1851, that was used to indicate 0° longitude. It passes through Greenwich, a borough of London, and terminates at the North and South poles. Because it indicated 0° longitude, it was also known as the prime meridian.