The equator is an imaginary line that goes around Earth's middle. It lies halfway between the North and South poles. It separates Earth into two equal parts. The part north of the equator is called the Northern Hemisphere. The part to the south of the equator is called the Southern Hemisphere. Image to left: The equator is an imaginary line that goes around the middle of the Earth. Credit: World Book illustration by Jeremy Pyle Near the equator, the sun shines almost straight down instead of at an angle, all year. Having this direct sunlight all year makes the area near the equator very hot. This hot region is known as the tropics. How to cite this article: To cite this article, World Book recommends the following format: "Equator." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.