equator: Planets and moons are divided in half by an imaginary line halfway between the North and South poles. This imaginary line is called the equator. The northern hemisphere is the half between the imaginary circle and the geographic North Pole. The southern hemisphere is the half between the imaginary circle and the geographic South Pole.
equatorial bulge: Most planets and moons are not perfectly round. Most of them are wider at the equator than at
