Extra credit on a test

I don't give many extra credit assignments, but I do like to put a bonus question on a test, worth a few extra points added to the overall score. These are sometimes questions about physics or astronomy ("What star is closest to us besides the sun?"), the school ("What year did the science building open?"), or other random things ("At what point in his life did your teacher start playing the bagpipes?"). Little fun things that they either know or can make a reasonable guess.

I'm giving a test tomorrow in my Honors Physics classes, and I'm trying to think of a good question to use as a bonus. Any ideas?

P.S. - Alpha Centauri, 1995-1996 school year, college or age 18