Like Hyperborea said, astronomy is a field where amateurs can contribute in a meaningful way. So it may be a good idea to look for this path.
But if you choose a carrier path as a researcher in a university or research institute, you should be aware of how difficult it is. To make research as your job, you must land on a job at a top ranked university or institute or you have to compromise at least to an extent. What you should know is how ridiculously difficult it is to get a tenure track job in such a place. The typical path is
Step 1. get a BS degree from top university (e.g., Harvard, MIT)
Step 2. get a Ph.D. from top university
Step 3. get a post-doc research job at top university/institute
Step 4. get a tenure track job at top university/institute
What's really important is that each step is like 100 times harder than the previous step. So, finishing 4 year college education in Prinston or whatever is a piece of cake when compared to getting a Ph.D. from a university of the same prestige. And doing a post-doc at a prestigious place is 100 times harder than doing a Ph.D. program at one of those top universities. And if you're a post-doc researcher at a steller university now, you will most likely end up in a not-as-shiny place in the end. So it's like at each step you should be among the top 1% to climb up the ladder.
While this is the most typical path, the first step (where you got your BS degree) is actually not that important because college education is quite elementary. It's like how well a professional athlete did in a PE class at elementary school. Probably he did exceptionally well. But it doesn't really matter.
Also, during step 2 and after, if your research is purely theoretic and doesn't require the kind of equipment available only at prestigious places, you might be able to get in if you didn't follow the previous steps (e.g., get a Ph.D. in a related field from a very good university and then do a post-doc at a top university in your target field). But you should know that this is as rare as winning a multi-million dollar lottery, and it's not luck; you do it by proving that you're a better candidate than other geniuses with steller track records. Another merit of working in a theoretical field is that you may be able to do a half-teaching, half-research job at a good research university because you don't need equipment or hire many post-docs.
Don't underestimate the difficulty of getting a (half-)research job though. I'm working as a post-doc in an intersection field of math, physics, and comp sci, which might be slightly less competitive than the most competitive part of theoretical physics. Even then, having a Ph.D. from MIT/Stanford/whatever means pretty much nothing when climbing up the ladder to step 3 and higher. It's pretty much a prerequisite, and you should be among the top of those who finished equally steller Ph.D. education. And in a theoretical field, you have a few unexpected competitors who didn't go to the most prestigious graduate schools but proved their excellence by publishing excellent research papers in extremely prestigious academic journals.
My current place is among the top schools in my field. But I see geniuses who got/will get a Ph.D. soon here having a very hard time going up to step 3. They were certainly among the top students who went to the best universities. But it's a whole lot different story to stay among the top of those who got Ph.D.s in your field from best universities. You might succeed in being a best genius among geniuses with Ph.D.s, but you've got another step waiting in front of you, where you have to be the best among those who survived.
If that's what you really want to do, I won't stop you. But you should be realistic. I'm not exaggerating. It's ridiculously hard and near-impossible to survive in one of the most competitive fields.
Edit: you might want to check related stack exchanges such as
http://academia.stackexchange.com/ and
http://physics.stackexchange.com/ There might be more specific ones too.
Edited: 2013-03-13, 4:26 am