Astronomy is the study of stars, planets, other bodies of mass and space. Astronomers uses hard science to explain the universe. When something cannot be explained in space, many theories are concocted by the astronomer. Then the theory is tested. The astronomer will predict a precise outcome based upon his theory, and then see if it occurs in reality. In this way a theory is either proved or disproven. This method is the basis of all true hard sciences.
Astrology is the study of the universe as well, but mostly how it affects our lives. Instead of using science, it relies on mysticism and magic. It offers only vague, subjective predictions of the future, that cannot be proven. More importantly, they cannot be disproven.
Now you know why the people earning income off of the climate business are called "climatologists" and not "climatonomists".