I designed one for my wife, we're playing in a new Champions game in a couple of weeks and she's playing an astronomy student, so I made a t-shirt for her through Zazzle. It's mildly amusing. It actually might make a decent gift if you know an astronomer.

Anyway, it's at http://www.zazzle.com/astronomers_t_shirt-235788989565885488, and even though the design is for a women's T, it can be redesigned for a man or for any number of t-shirt styles.