What is the longest parallel of latitude called?

The longest parallel of latitude is the Equator, which is located at 0 degrees latitude. It is significant because it divides the Earth into the Northern and Southern Hemispheres and is the reference point from which all other lines of latitude are measured. The Equator has a length of approximately 40,075 kilometers (around 24,901 miles), making it the longest of all the parallels.

In contrast, the Tropic of Cancer and the Tropic of Capricorn are located at approximately 23.5 degrees north and south latitude, respectively, and are shorter than the Equator. The Arctic Circle, situated at about 66.5 degrees north latitude, marks the southernmost point of the region where the sun does not set on the summer solstice, and it is also shorter than the Equator. Hence, the Equator stands out as the longest parallel of latitude, which is why it is the correct answer.