Is zenith distance at upper culmination lesser than zenith distance at lower culmination?
Yes, the zenith distance at upper culmination is less than the zenith distance at lower culmination. The zenith distance is the angle between the zenith (straight overhead point) and a celestial body. At upper culmination, the body is closest to the zenith, resulting in a smaller zenith distance. At lower culmination, the body is furthest from the zenith, leading to a greater zenith distance.