Here's why:

* Celestial Sphere: Imagine a giant sphere surrounding the Earth, on which all the stars and celestial objects appear to be projected.

* Ecliptic: The ecliptic is the apparent path of the Sun across the celestial sphere over the course of a year. It's the path the Sun follows due to the Earth's orbit around it.

Let me know if you have any other questions about the celestial sphere or related concepts!