Geocentric

Geocentric, in Astronomy, refers to those motions which have the earth for centre, or which are measured in relation to the earth. Thus, the motion of the moon in a slightly elliptical orbit round the earth at one focus is called geocentric. The geocentric latitude of a planet is the angle made by the line joining it to the earth with the plane of the ecliptic. The geocentric longitude is the angular distance of the planet measured along the line of the ecliptic from a certain standard point, known as the first point in Aries.