And this is why they invented Google:
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970411a.html
He could have asked one of his retinue to look it up for him - heck, he could have also asked his valet or some other aide to come up with a smarter question for him to ask.
Well just damn. You're right. After all we all know that leaders should know everything little thing about anything.
I know this may be a little above you, but knowing how astronauts use the bathroom is probably not on the top of the list of most world leaders. And it's one of those questions that everybody asks. But hey, bashing the Queen and Prince Philip seems to be the most popular pasttime around here of late. Go for it.