The Equator is an imaginary line that runs around the center of the Earth at 0 degrees latitude, dividing the Earth into the Northern and Southern Hemispheres. It is a circle of latitude that is everywhere equidistant from the geographic poles and lies in a plane perpendicular to Earths axis. The latitude of the Earths equator is, by definition, 0° (zero degrees) of arc. The Equator is the only line of latitude that is also a great circle, meaning one whose plane passes through the center of the globe. The Equator is approximately 40,075 kilometers (24,901 miles) long. Earth bulges slightly at the Equator due to its spin, making Earths circumference at the Equator longer than its circumference at the poles. The plane of Earths Equator, when projected outwards to the celestial sphere, defines the celestial equator. The Sun appears to travel along the Equator at the equinoxes in March and September. The Equator receives more incoming solar radiation over the course of a year than other locations more poleward, and above the Equator is a zone of low atmospheric pressure called the intertropical convergence zone (ITCZ).