We’re an hour away from Superman’s birthday, according to old comics lore.
Stories in various media conflict — even within their own continuity at times — over both when the Man of Steel was born on his homeworld of Krypton, relative to our Gregorian calendar, and when his rocket landed on Earth. As I wrote a few years back, though, DC Comics editor Julius Schwartz and writer/historian E. Nelson Bridwell noted in response to reader mail with a giant wink that Superman barely seemed to
age because his birthday only came around every four years.

Panel from 1st story in Action Comics #1 © 1938 DC Comics.
Script: Jerry Siegel. Pencils, Inks, Letters: Joe Shuster. Colors: Unknown.
On the heels of the February 29th date seeing print in a 1976 DC calendar and those occasional lettercolumns, Alan Moore used it in the acclaimed tale “For the Man Who Has Everything”, drawn by his Watchmen co-creator Dave Gibbons for 1985’s Superman Annual. The same calendar gave alter ego Clark Kent’s birthday as June 18th, however, carried over from a 1973 story establishing the date as that of Kal-El’s arrival on his adoptive planet. Writer Cary Bates may have chosen that month based on the character’s 1938 introduction in the pages of Action Comics #1, bearing a cover date of June but on newsstands at least one month prior — despite which DC celebrated Superman’s 50th anniversary in 1988 with a party on the Friday before Leap Day, instead of in April, May, or June!