The Celestial Sphere helps in understanding:

The Celestial Sphere is an essential concept in astronomy and navigation that models the positions of stars and celestial bodies as if they were projected onto an imaginary sphere surrounding the Earth. This framework allows navigators and astronomers to represent and understand the movements and locations of celestial bodies relative to one another and to the Earth.

By using the Celestial Sphere, one can visualize the positions of stars, planets, and other celestial objects in the night sky, which is crucial for navigation by the stars. This model simplifies the complexities of celestial navigation, as it provides a systematic way to determine the altitude and azimuth of a star, which are vital for successful maritime navigation. Understanding these relative positions is key for sailors and navigators to establish their position on Earth and to plot their courses accurately.

The other options, while they touch on important aspects of earth sciences and physics, do not align with the specific function of the Celestial Sphere in helping with celestial navigation and understanding the layout of celestial bodies in the universe. Thus, the focus on celestial positions makes the correct answer particularly relevant.