Here's why:

* Astronomy is the study of celestial objects (like stars, planets, moons, comets, etc.) and their phenomena. It encompasses their:

* Formation: How they came to be.

* Composition: What they're made of.

* Motion: How they move through space.

* Evolution: How they change over time.

While other sciences might touch upon aspects of stars and planets, astronomy is the dedicated and primary field of study for these celestial bodies.