How To Make Sky Sphere Static on One Axis?

The game setup is a vertical Scroller. A rocket ship game going into the skies. My Sky Sphere is Rotating Perfectly Alogn Y… But When I Move My Hero/Rocket Left or Right, the Sun Follows the Hero.

I would like to somehow keep the sun on one axis, not be allowed to move left or right, just downward like a sun setting. Adding depth to the background and world.

Does anyone know how to keep the sun in background along one-axis (preferably not to move right or left, when my rocket or hero does)?

Thank you