It seems more enchanting than even throwing coins into a wishing well (unless it requires three coins).
Symbolically speaking (psycho-spiritually) a “star” represents knowledge and feelings that are beyond our habitual earthly experience. (Physically, a star resides “above” us and our earthly plane, and represents an influence that comes from above—like a heavenly influence). A “star’s” light can also provide us with direction when we travel at night. Similarly, higher knowledge and heavenly affections can show us the way (enlightenment) through tough times of inner darkness and mental obscurity.
Therefore, “wishing upon a star” is the desire to obtain some noble goal that lies outside our usual self-centered and worldly nature.
God gives special attention to these higher wishes, and therefore, they have a better chance of coming true!