“Well… it’s actually astronomy, not astrology. It’s alright, people tend to mix them up all the time.” (Slightly hesitant to make the correction, doesn't want to be rude)

“I think what we should do is try to understand where she’s coming from. I’m sure all of us have similar goals, but we’re letting minute details cause disagreements.” (Giving a straightforward explanation)  

”If we look at unexplained phenomena like that from a scientific perspective, we could come up with some much more fascinating answers than just saying that aliens did it.” (Here he's going off a bit of a tangent, and his passion for the subject shows a lot. He still isn't being condescending, though).