Calvin and Hobbes by Bill Watterson for September 25, 1990
Calvin/Spaceman Spiff: In a scientific mission to discover what happens when two planets collide, Spaceman Spiff drops anchor! The anchor catches on a hillside! Spiff downshifts and guns the motor! Imperceptibly at first, the planet slowly moves, towed along by our hero, until......breaking orbit, Planet 6 picks up speed, hurling toward Planet 5!