Academic Positions in Physics/Astronomy EDIT/TLDR: Professorships are hard to find so I’ve never expected one. With recent PhD admissions success, is becoming a university/liberal arts professor now realistic and how can I best meet that goal?

I was recently accepted into an astronomy PhD. To give a rough characterization it is ranked in the US top 10-20 for physics/astronomy, whatever that’s worth. My new department paints an optimistic future picture but I wanted to get an objective view. With this prior, what can I expect in terms of career outlook?

From my undergrad experience in physics as a TA+RA I love to teach and research, and want to do both as a job whether that is at a research university or liberal arts college. I would also be grateful to teach at a community college, slightly more so than being a staff scientist at an observatory, but would still prefer to get the chance to research as well.

My undergrad productivity was pretty good - I was able to turn all my projects into publications, so hopefully I can build up from that. What other steps should I take to improve my chances to become a professor, especially at liberal arts colleges? Should I try to TA beyond my second year?
With recent PhD admissions success, is becoming a university/liberal arts professor now realistic?


First, you should not expect to get accurate advice about this.  As a new graduate student, you are at least seven years away from being competitive for a faculty position.  Nobody can predict the job market seven years ahead.

Currently, faculty positions in physics are extremely competitive.  There are many massively qualified candidates for very few positions.  Often, new assistant professors have more publications than the retirees they replace.

Owing to falling birth rates, there are too many colleges in many parts of the world.  As a result, some will fail financially before you finish your PhD.  Private liberal arts colleges that do not have endowments will be the first to go.  During the current pandemic, enrollment may fall 20%, which is fatal to many institutions if they are not bailed out by the government.

Community college hiring is also competitive.  It has different practices from research universities, but do not listen to anyone who tells you that if it's not elite you can easily get a job there.  


  What other steps should I take to improve my chances to become a professor, especially at liberal arts colleges? 


For any institution, publish a lot.  The number of publications you need to get a job keeps going up.  Physics research is really expensive.  If you want to have a choice of employers, you need to learn to do research that is really cheap.  A good research university lab has a budget well into the six figures, but you are likely to get an annual budget in the low three figures when you are an assistant professor.  It might be zero.  For liberal arts colleges, it is essential to include undergraduate students in your research.  Start supervising student projects as early as possible.


  Should I try to TA beyond my second year?


In my opinion, this is irrelevant unless you learn something about teaching by doing it.  If you are TAing for someone who does not know how to teach, you are wasting your time.  If your university has excellent TA training, take it.  Seek to teach a whole course by yourself.