What is the ecliptic fundamentally the projection of onto the celestial sphere?

Answer

Earth's orbital plane

The ecliptic is the geometric path traced by the Sun, which is fundamentally the projection of the plane containing Earth’s orbit around the Sun onto the celestial sphere.

What is the ecliptic fundamentally the projection of onto the celestial sphere?

#Videos

The Ecliptic: Crash Course Kids #37.2 - YouTube

sunorbitplanetpathecliptic