A Study on the Sun-Moon Trajectory Differences

Measuring the solar flux distribution at the concentrated optical spot of a solar tower power plant is a research focus. Our previous studies verified that the solar flux distribution of the field of heliostats as the solar tower concentrator can be calculated by measuring the lunar concentration ratio distribution using the full-moon light. This paper proposed an algorithm for matching daily Sun and Moon trajectories, i.e., matching Moon or Sun trajectories for any Sun or Moon day, to investigate the differences of Sun-Moon trajectories. The Sun and Moon trajectories are calculated for 2024, and results indicate that all the daily Sun and Moon trajectories are parallel on the celestial sphere centered at the viewer point. The matched Sun and Moon trajectories are specially illustrated for eight typical dates in 2024 and 2023, and the 12 Moon trajectories for the full-moon days in 2024 and the matched Sun and trajectories are compared. The simulations show that the minimum altitude angle difference of the matched Sun and Moon trajectories reaches 0.0165°.