Can a B.S. in Biology, pursue M.S. in astronomy or planetary science?

[FLPrincessGrad]

I am earning a b.s. in biology and I'm interested in astronomy...

[wavygarfield]

I believe you could, especially if you were interested in astrobiology. It depends on school of course, but those that would allow it would likely need you to make up classes you didn't get in your undergrad to build a basis for the astronomy route.

[scytoo]

It really depends...

Remember that astronomy as a whole is the same as "astrophysics", which is just "the physics of things in space". You need a very strong physics background for an Astronomy PhD, and if you don't already have the equivalent of a physics major or close to it, you'll have to spend another couple of years catching up on that. I'm assuming you don't have extensive research experience in astronomy either, so you'd likely have to do a Masters first before applying to PhD programs. Astronomy is a hugely competitive field. 

[Jac33]

Why not? Of course, you can! If you don't understand, I'll explain you. When such thoughts come to your mind, it occurs for a reason. This moment is decisive, and if you make a wrong decision, you'll regret it. Well, you have a degree in biology and are interested in astronomy. The fact that YOU'RE INTERESTED IN IT means you'll progress. You may not have enough knowledge, but you have a thirst for knowledge. Perhaps, you'll need to spend time preparing for this program before applying to college, but it's worth it. Take it from me. Now I'm working as an astronomer, but my first college degree was in Physics. And one day, I found myself in the same situation. As you see, I decided to change my life a little, and it was my best decision. Now I can do what I love and feel happy.