Editor’s Note: Typically, we do not run a cartoon from the same artist two weeks in a row, but this beautiful piece from xkcd/Randall Munroe deserved it. More on Randall follows. — John Cronin
xkcd is the webcomic creation of Randall Munroe, an extraordinarily popular web presence whom we feature regularly on EarthDesk. He draws on science themes often and has been nominated for a Hugo Award twice, thanks to his loyal science fiction fan base.
Read more about Randall in this New York Times feature.