I should start out this post by pointing out that, at the time of writing, I am still in graduate school and have not, in fact, gotten my PhD yet. That being said, I think I can look back at the past 4 and a half years and come up with some sort of kernel of wisdom that might be useful to someone else.
Like many graduate students, I decided to go to grad school after getting my undergraduate degree in Astrophysics because that was what you were supposed to do. While the academic track is incredibly difficult, it is fairly straightforward. And that means it's (somewhat) safe. As an undergraduate student, I worked in a lab, and did one-on-one research with a professor. So I had some idea of what a career in research might look like. And I didn't mind it.
When I started grad school, I was fortunate enough to have an adviser with funding, which meant that I didn't have to TA. I focused on my research during that first year, and was fairly productive. I got to travel for conferences, and generally enjoyed grad school. However, while I was attending these conferences, I had the chance to speak with other grad students as well as post-docs about their academic careers. I found that many post-docs were having trouble getting jobs. Some seemed downright miserable. Even graduate students seemed stressed, overworked, and tightly wound. This was the first red flag for me.
In my second year, I got the chance to teach. A lot. I mostly taught lower-division undergraduate classes, since I was afraid that if I tried to teach an upper division course, I would be outsmarted by my students. There's that imposter syndrome rearing its ugly head. But that's another post for another day. What I discovered in that second year was that I absolutely loved to teach - especially the Gen-Ed courses. Some of these students were taking Astronomy because (let's be honest), they thought it would be easier than Physics and they needed to fulfill a physical sciences requirement. Some had a lifelong passion for science, maybe for Astronomy in particular, and wanted to explore it further. Some had a vague understanding of what Astronomy was, and thought it sounded "cool." I loved them all. It became my personal goal to get each and every one of them as excited about Astronomy as I was. Of course, teaching like that takes time. It takes time away from working on research, it takes time away from my graduate courses, and it takes time away from sitting at home playing Call of Duty. It didn't matter.
I started taking more of an interest in physics and astronomy education, and became convinced that my calling was to be a high school physics teacher. To do that, I would have to take graduate classes in the Education Department, pass several standardized exams, and get my teaching credential. When I pitched this idea to my department, professors were (rightly) concerned that such an endeavor would take time away from my research and slow me down on my path to graduation. To me, it didn't matter. I would find time for all of it. Somehow. Whatever, I would figure it out later. I'll sleep when I'm dead.
In my third year, I found myself completely enamored with science education at all levels. I wanted to be a high school teacher. I wanted to be a professional outreach coordinator. I wanted to teach at a community college. I had no idea what I wanted. All I knew was that, when I attended a national astronomy conference, I found myself attending all of the outreach and education talks, and very few of the science talks. I spent hours talking to the high school teachers who were collaborating with researchers, and community college teachers who were experimenting with innovative new teaching techniques. I learned about "student-centered teaching" and why lecturing just doesn't cut it anymore.
It occurred to me that I was excited about education and outreach the way I was supposed to be excited about science research. Add to that the fact that most post-docs I talked to couldn't find a position at a 4-year university, and had to move from city-to-city for years before settling down. I was finally starting to think seriously about a career after grad school. At this point, I had passed my comprehensive oral exams and advanced to candidacy. It didn't make sense to stop the PhD, but I knew I didn't want a "traditional academic career." So what did I want?
The more I talked to grads and read about science education, outreach, and communication (SEOC) programs at other universities, the more I realized how versatile a PhD could really be. I still don't know exactly where I'm headed, or what my career will be. Come this Fall, I'll be applying for a myriad of jobs in a myriad of career paths. At this point, if I had to go back and do it again, I'm not sure that I would chose to go to grad school for Astronomy. Maybe I would have chosen a school that offered a Physics Education PhD, or gotten my Master's in Education. Then again, having a STEM PhD officially makes me a "scientist" in the eyes of the public, and that's a powerful pulpit for a science educator. It's hard for me to give advice to someone in a similar position about whether or not to start (or continue) graduate school. But the turning point for me was in reflecting on how I spent my time (or at least, the enjoyment I got out of time spent doing science communication in one form or another). It was also the realization that if I tried to do it all, I would never sleep, eat, or see my husband. It's impossible - I had to chose a path and follow it.
So ask yourself: What do you gravitate toward? Is there something that's pulling you away from research? Something you find more rewarding? More enjoyable? Follow your instincts. Try new things while there's still time. Take a class, if you can. Go to a conference that doesn't focus on research. The job market is saturated with PhDs. If you want a career in academia, be prepared to fight for it. But if you don't, your skills and passion might be valued highly somewhere else. Think about it. Talk about it. It's up to you!