The imaginary line that runs north to south separating the sky into east and west is called the ?
O celestial equator
O zenith
O ecliptic
O meridian

MERIDIAN.

Explanation: Meridian can be defined as an imaginary great circle on the Earth's surface, passing through the geographic poles i.e from north to south. This in turn separates the sky into East and West. They connect the points of equal longitude, as measured in angular degrees east or west of the Prime Meridian.

's the question?