In: Physics
Here is a typical question which I have been asked many times while giving public lectures in various places. While I know one of the paths like Diploma, Masters and PhD but sometimes this is not so obvious for that eager young person who thinks to go on that path. So what that would be?
You start out getting a Bachelor of Science in a related field. This could be physics, astronomy, mathematics, or possibly chemistry. Depending on which country you are planning to go to grad school in, specializing at this stage may not be as important as in later stages. However, note that in the UK, for example, it is almost unheard of for a student without a Bachelors in physics (almost always with a minor in astrophysics) to gain a place in grad school for astronomy.
After doing the BSc, you would go on to get a Masters degree in astronomy, which would set the stage for a PhD in astronomy. The PhD (and to some extent, the MSc) will have you specialize in a specific area in astronomy, such as star formation, planetary studies, or cosmology.
After doing the PhD, you would get a post-doc at a university or research institute. This is typically a three-year job where you do research in your chosen area. Most astronomers do two or three post-docs.
After this, you could become a professor or research associate at a university or an in-house research astronomer at an observatory. Universities or observatories are typically the only places to be a "professional astronomer", and depending on the position, would give you time to do your own research in conjunction with other duties like teaching.