Here's why:

* Geology is the study of the Earth, its composition, structure, and history. This includes the study of rocks, minerals, and the processes that form them.

* Stars are celestial objects that are studied by astronomers. Astronomy deals with the universe, stars, galaxies, planets, and other celestial bodies.

While there are connections between geology and astronomy (for example, studying meteorites), a geologist's primary focus is on the Earth and its geological features.