Click here to see an example of a secure and flexible seat in trot. Watch closely as the rider's hips, pelvis, and legs flex freely with the horse's movement. Horse's willingly raise their back up under a seat like this, probably because it feels a bit like getting a gentle back rub with each step.
The celestial sphere is divided by the celestial equator. In astronomy and navigation, the celestial sphere is an imaginary sphere (ball) of a very large unspecified size. The sphere is concentric with the Earth. This means that the celestial sphere and the earth have the same centre. They also rotate upon the same axis.
celestial equator. n. 1. (Astronomy) the great circle lying on the celestial sphere the plane of which is perpendicular to the line joining the north and south celestial poles. Also called: equinoctial or equinoctial circle.. celestial equator-the great circle on the celestial sphere midway between the celestial poles. equinoctial, equinoctial circle, equinoctial line. great circle-a circular line on the surface of a sphere formed by intersecting it with a plane passing through the center.