ASTR 1101 Study Guide - 45Th Parallel North, Celestial Equator
Document Summary
The zenith is an imaginary point directly above an observer. The nadir is the point exactly opposite the zenith. As you move the observer around on the map of the earth, do the zenith and nadir change relative to the observer or stay the same: change, stay the same. The meridian is an imaginary line that runs exactly north-south and passes through the zenith. It splits the sky into eastern and western halves. Relative to the observer, does the meridian change as you move the observer around: stays the same, changes. The north celestial pole (ncp) is where the projection of the earth"s north pole touches the celestial sphere and the south celestial pole (scp) is where the projection of the earth"s south pole touches the celestial sphere. From the observer"s point of view, do the ncp and scp change as you move the observer around: change, stay the same.
