February 18, 1930: This image has been distributed by the DC17 Worldcon bid to remind us on today’s date Clyde Tombaugh documented the discovery of the planet Pluto.  (The Wikipedia says there were many “prediscoveries” but people didn’t recognize them as such before Tombaugh did his work.)

One question: Can anyone explain why Goofy is Mickey’s friend, but Pluto is Mickey’s planet?