CELESTIAL NAVIGATION

                                                        CELESTIAL SPHERE

.For the purpose of astronomical navigation,the earth is assumed to be surrounded by a concentric sphere,on infinite radius said as CELESTIAL SPHERE,an  imaginary sphere of infinite radius with the earth as it's center
                   
                                                           CELESTIAL POLES

 Are the two points on the celestial sphere where the axis of the earth proceed would be meet called as  CELESTIAL POLES.