Astronomy is one subject that most of us didn't study in our high school. Only a small percentage of high school students get the opportunity to attend formal classes of this subject. It does not matter that we have learnt the subject in a class or not, what really matters is that the subject never fails to captivate us with its magnificence. As Plato quotes it: "Astronomy compels the soul to look upwards and takes us from this world to another." There is no age to learning anything. I do get a lot of messages on The Secrets of the Universe and most of them read, "How to start studying astronomy? What are the best books for this subject? etc." So I have decided to share my own experience of self studying astronomy and I'll share some good sources and books that will help you too.
I wasn't taught astronomy in school. I studied physics, chemistry and mathematics but no astronomy. But I got interested in this subject when I was in 7th grade. My elder sister gave me a book on Mars which had interactive images of the Red Planet. I simply enjoyed looking at those beautiful images. Then a couple of years later, I was in a book shop with my parents and I saw a book named "ASTRONOMY" by Duncan John. I opened the book and I was amazed. The index of the book covered so many topics. From planets to stars and from nebulae to galaxies, it contained everything. The best part of the book? Plenty of stunning images from the Hubble Space Telescope. I bought that book and it was my first formal effort to self study the subject. Even today, I recommend this book. If you want to start with astronomy, start from the very basic: The Solar System. Read about the planets first. It will really spark your interest. This book has a detailed description of the solar system and the magnificent images will really "take you from this world to another". You can buy this book here.
After reading this book, I was searching for more on the internet. It was at this time when I stumbled upon a website that I think became a turning point in my life. It was Sky-and-Telescope. As I surfed the website, I came across a section named "This Week's Sky at a Glance". This section actually had sky maps for the coming week and also using them one could spot the planets. I thought of giving it a shot. I used the sky map and found Mars and Saturn. Now this might not look exciting but to a boy, who is 15 and lives in a light polluted city and who really has deep interest in astronomy and has only dreamt of seeing the planets, it was a lifetime achievement. This was the turning point because it was on that day, I decided to pursue a career in astronomy.
So while reading books on astronomy, don't forget to look up at the stars. Observational astronomy should be your next step and Sky-and-Telescope website is one of the best options for that. Seeing my interest in astronomy, my father bought me a small refracting telescope. Buying a small telescope should be your next step. Remember, your first scope should not be too expensive. Start with the basic and then, when you have the confidence, buy an expensive one. But before buying a telescope, take advice from the experts.
So far, I had not come across astrophysics. It was only astronomy. One day I was reading about stars on the internet (Wikipedia). It was then, when I came across a few typical terms like Asymptotic giant branch, red giant branch, color index etc. I got confused. What are these? After a week of study, I found that these all are a part of what is known as the Hertzsprung Russell Diagram. This was my first formal encounter with astrophysics. These were the topics of stellar evolution. There are only two sources that I used to study astrophysics. First is the Internet. Do study something new everyday. The main advantage is that if you come across any typical term that you don't know, you can always, at that very instant search for it. The book that I recommend to get started with astrophysics is "An Introduction to Astronomy and Astrophysics" by Baidyanaath Basu. This book introduces the basic concepts of astrophysics with minimal mathematical details in a beautiful way. You can buy this book here.
There are numerous books on astronomy that you can read. I shared the books and sources that I followed. The key to learning is to keep moving. Keep learning everyday, no matter what. If you wish to study astronomy as a hobby, don't go into too many mathematical details. Just relish the subject. However, for students who wish to pursue a career in astronomy and astrophysics, your main focus should be physics and mathematics. In physics, master electrodynamics, statistical mechanics, spectroscopy and quantum mechanics as they are the one of the most widely used subjects in astrophysics. And of course, do not forget to look at the stars.
Now after 9 years, when I tell my friends, "Hey look there, that's Mars." They ask me, "How do I know?". I simply smile and say, "Long story...."