near which feature of the celestial sphere are planets located and why?

Answer 1

The celestial equator, or ecliptic.

The most widely-accepted theory about the formation of the solar system has it originating as a cloud of spinning dust and debris. Over time the debris began to coagulate and clump together under the influence of gravity. But that initial spin had to be conserved (Law of Conservation of Angular Momentum, Physics 101), so the accumulated debris coalesced into the sun and the planets, all orbiting it the same direction, roughly in a plane.

Answer 2

Planets are located near the ecliptic, which is the apparent path of the sun in the sky. This is because all the planets including earth are in roughly the same plane.