I would recommend listening to Astronomy 161 (Solar system), 162 (General astronomy, like life cycles of stars etc.) and 141 (Life in the universe).
These are three amazing and engaging Ohio University Astronomy courses uploaded for free by Richard Pogge. His lecture style is really great and I've yet to loose interest despite of listening through all of them multiple times (each one is about 45 lectures of 40 minutes each).
I'd recommend these to anyone interested even a bit in astronomy. They're entry level courses so you don't need to know anything at all about astronomy (or geology, biology etc. in the case of 141) before going through them, although in that case I'd definitely listen to 161 first, then 162 or 141.