Calvin and Hobbes by Bill Watterson for September 26, 1990
Calvin/Spaceman Spiff: Pulled by Spaceman Spiff, Planet 6 is about to collide with Planet 5! With no time to lose, our hero cuts loose the anchor and flies to safety! The planets crash, grinding and shattering with awful force! Planet 5, being smaller, is crunched to dust! Only 6 remains! Miss Wormwood: Time! Pass your papers forward. Calvin: Time?! I just finished the first problem!