what is the imaginary line around the centre of the earth called
An equator is the intersection of the surface of a rotating spheroid (such as a planet) with the plane perpendicular to the axis of rotation and midway between its poles. On Earth, the Equator is an imaginary line on the surface, equidistant from the North and South Poles, dividing the Earth into Northern and Southern Hemispheres. It is about 40,075 kilometres (24,901 mi) long, of which 78.7% lies across water and 21.3% over land.