Longest Line of Latitude Identification

Lines of latitude, also known as parallels, are imaginary circles on the Earth's surface that are parallel to the Equator.

These circles measure the distance north or south of the Equator.

• The Equator is the line of latitude at $0^\circ$. It is the largest circle that divides the Earth into the Northern and Southern Hemispheres.
• Other lines of latitude, like the Tropic of Cancer ($23.5^\circ$ N), Tropic of Capricorn ($23.5^\circ$ S), and the Arctic Circle ($66.5^\circ$ N), are progressively smaller circles as they move away from the Equator towards the North and South Poles.

Because the Equator represents the Earth's widest circumference at its center, it forms the longest line of latitude.

Therefore, the Equator is the longest line of latitude on the globe.