Happy 75th Birthday, Superman!
According to The Photo-Journal Guide to Comic Books by Ernst and Mary Gerber, Action Comics #1, featuring the first appearance of Superman, was published on April 18, 1938. That makes today Superman's platinum anniversary. Or diamond, depending on which guide you prefer.
Actually, the word "septuagenarian" refers to anyone between 70 and 79, so Superman's been one for five years already. I couldn't find a word for just 75, though, so I'll have to settle for this title.
Update: I wanted to do something to celebrate the day, so I bought myself a copy of the recently published Superman: the Unauthorized Biography by Glen Weldon, the "go-to comic book guy" of National Public Radio. It looks like a fun book. I'll review it here after I've finished it.