I agree with what he said for sure.
I happened to know what I wanted to do in college (sort of). In high school after taking an economics class it sort of gave me a super small taste of business topics and I knew that whatever I did, I wanted to be successful, and by successful I mean make enough money to where I would not have to worry about paying bills and being able to afford doing the things I want to do with my life.
So...because of my interest/borderline obsession with money, I felt that business would be good for me. Everybody I knew who had a dad who "was a businessman" was pretty damn well off, and so I said to myself, I want that in my life. I applied to CU as a business major and got in, and they put me in as a management major just by default. As it works here, you have to take intro classes to each business discipline - (management, marketing, finance, accounting) so after I had all 4 of those intro classes I found that finance was what interested me most, and what was also going to be a big challenge for me.
Also, in my first 2 years of school I worked as a bank teller so I got a small eye into the financial services industry and I enjoyed it. I liked the responsibility, I liked the respect I got even though I was young, and I liked being able to help people with their money (on a small scale of course). Anyway, I'll wrap this novel up. I decided that I really enjoyed helping people, and that I wanted to feel good about what I did for a living so I decided I wanted to be a financial adviser. About a month before graduating I landed a job with a great financial advising firm and so for the past 5 months I have been learning/training/studying/getting licensed for my job as an adviser.
Sorry for the long story, but hopefully that helps you somehow. It takes time to figure out what you want to do, that's for sure.
Any college or university you end up at will have tons of help with choosing careers/majors.
I started off as a Journalism major, because I love writing and seeing my work published. However, with the economy these days, newspapers are going out of circuit, and one by one they're dying off. My major was nicknamed, "the dying breed." I realized that more and more newspapers were moving into an online direction, and that isn't what I wanted. I love the feel of paper hot off the press in my hands and actually being able to hold something I reead. So I switched my major to English, that will I still get to write, and Mass Communications so that if I can't make it with writing, I can fall back on PR and Advertisting.
You love astronomy, space, and the universe, I say go for a major related to it. Of course it will be difficult, but if you are determined and give it 100% effort you'd be surprised at what you can accomplish.