The equator is important as a reference point for navigation and geography. It's an imaginary line that divides the Earth into two equal halves, and it forms the halfway point between the South Pole and the North Pole at 0 degrees latitude, according to National Geographic. It is also important because twice a year, during the spring and autumn equinoxes, the sun passes directly over it.
The Earth is widest at the equator. It's understood that the total distance around the Earth at the equator is believed to be 40,075 kilometers. It's also at this point that the Earth’s diameter is widest, believed to be around 12,756 kilometers. According to Lilly Ponds Art Center, the equator is longer than the Earth's circumference because, unlike the circumference that is measured in a straight line, the equator traverses various topographies. These include mountain ranges and sea levels, which add a few kilometers to its total length. According to National Geographic, the rotation of Earth results in a phenomenon known as equatorial bulge. The equatorial bulge also affects the ocean, creating slightly higher sea levels in equatorial regions. As the latitude lines increase in size, a point on the Earth’s surface has to travel faster in order to complete a revolution in the same time period.