Superman comic strips ran in newspapers from the 1930s through the 1960s, under the title Superman. Printed daily, they were the first stories to go into detail about the planet Krypton, expounding on Jor-El and Lara. The first strip was published on January 16, 1939, with a separate Sunday strip added on November 5, 1939, running continuously until May 1966. At its peak, the strip appeared in over 300 daily newspapers and 90 Sunday papers, with a readership of over 20 million.