Being a big superhero fan, it's important to know that according to DC comics, today, February 29th is considered Superman's birthday!
Comics of the 1960s through 1980s describe Superman's birthday as February 29.Superman’s official birthday was established in the Silver Age when editor Julie Schwartz declared that Superman’s birthday was on February 29th in a number of letter pages.
Of course, there have been several months tossed around.Action Comics #149 (Oct. 1950) gives October as Superman's birthdate but that never took.
June 18th, however is considered Clark Kent's birthday for a couple of reasons. One is that Superman/Clark Kent first appeared in ACTION COMICS #1 in June 1938 (created by Jerry Siegel and Joe Shuster) and June 18th (the date of the issue I believe) is seen as the day that the Kents (Jon and Martha) found baby Kal-El's rocketship and adopted him. The first mention of Superman recognizing his
Earth birthday was in ACTION COMICS #241 in 1958. SUPERMAN #263 (1973)
puts Clark’s birthday on June 18th.Of course, giving Clark a birthdate in June and Superman a birthday in February helps distance the two and keep his identity secret!