Question 1747Navigation General

The correct answer is D) Measurement of time is along the celestial equator. The use of a mean sun as the reference for solar time is due to the variations in the Earth's rotational speed (A), the non-constant speed of the Earth's revolution around the sun (B), and the fact that the motion of the apparent sun is along the ecliptic (C). However, the measurement of time is not along the celestial equator, but rather along the ecliptic, which is the plane of the Earth's orbit around the sun. This is why option D is not a reason for the use of a mean sun as the reference for solar time.