Even when two words might share a common origin, we naturally cannot assume that they still have the same meaning. No one is going to confuse a handgun for a handbag, just as you wouldn’t mistake someone’s biology for their biography. And as we gaze up into the night sky and behold the wonders of the universe, we must also recognize that astrology and astronomy are not at all identical.
Astronomy is the scientific study of the material universe that exists beyond the atmosphere of the Earth. Today, professional astronomers can be divided into those who study observational astronomy and those who study theoretical astronomy. The former attempt to collect and analyze data, while the latter may use computer or analytical models. They’re complementary and can support one another’s findings.
Astrology, on the other hand, is not a “science” in the traditional sense. Instead, it has more to do with fortune telling, tangentially related to palm reading or tarot card reading, except astrologists look to the movement and relative positions of celestial bodies to determine or predict their impact on human affairs. If you’ve ever read a horoscope talking about how a certain planet is currently high in your sign, for instance, you’ve read something written by an astrologer.
What do astrology and astronomy have to do with astrophysics? In short, while astronomy specifically refers to the science of celestial bodies and outer space, astrophysics is the application of physics to the understanding of astronomy. Since modern day astronomers use physics, though, the two terms have become largely interchangeable.
For the most part, you’ll hear people refer to Neil deGrasse Tyson as an astrophysicist (or as a “badass”… check your memes), but it would not be inaccurate to call him an astronomer. It would be entirely incorrect to call him an astrologer, though, especially since he is an ardent opponent of pseudoscience.
You may, however, refer to Tyson as a cosmologist (but not a cosmetician), since cosmology is the study of the universe in regards to how it started, where it’s going, and where it’ll eventually end up. These are the people who talk about the Big Bang theory and the singularity… and not the people who will tell you that now is a good time to focus on advancing your career since the stars are aligned a certain way.