what feature of the celestial sphere is found by essentially expanding the Earth's equater outward to the celestial sphere

Celestial equator.

Explanation:

The celestial equator is a strand of the celestial sphere that is essentially expanding the Earth's equater out of the celestial sphere.

In summary, the celestial equator is an extensive circle resulting from the intersection of the celestial sphere with the plane that is perpendicular to the terrestrial axis in the center of the earth. We can define it as a projection from the equator to space.