October 10 CNN News reported that Buzz Aldrin is going to be making his cameo appearance on 'Big Bang Theory' October 25. He recently had a guest spot on 'Dancing With the Stars' and a cartoonized appearance in 'The Simpsons'.
In Buzz's upcoming episode, the cast is celebrating Halloween in Stuart's comic book store and Buzz gets to cameo as himself. That is all that CBS will say about the episode. It is unknown if Howard will be on earth by then or not, but that seems like the most likely way that the cast would have Buzz on the show.
As a group of nerdy scientists, and Penny, they will likely be excited to see the famed astronaut that was the second man on the moon.
Buzz is joining a long line of other space famed actors to do cameos on the show. Among them are Leonard Nimoy, Wil Wheaton, Brent Spiner and fellow astronaut Mike Massimino.