Yesterday, as I finished reading the current issue of New Scientist, I turned over the last page and was struck by a watch advertisement on the back cover. The wristwatch appeared to be in lunar orbit, and had the kind of multi-dial face meant to appeal to a would-be astronaut. Indeed, according to the ad copy, earlier iterations of this very model, an Omega Speedmaster chronometer, were worn by members of the Apollo missions. In and under the headline, "THE DARK SIDE OF THE MOON," the ad's text referred twice to an outpost that only right-stuff crews have seen "with their own eyes."
I made that same labeling mistake once myself, and was embarrassed by it, so I remain sensitized to the important difference between the far side of the Moon, forever hidden from the earthbound among us, and the dark side, which changes all the time as the Moon circles the Earth. At full Moon, the dark side and the far side are one and the same. But the same cannot be said for the rest of any month. Most times, moonstruck earthlings can easily see our satellite's dark side without benefit of a rocket ship or even a telescope.
Grade-school teachers report that the majority of students need to engage in hands-on activities involving globes and flashlights before they can master the Moon's phases. For whatever help it may provide, a schematic diagram of the lunar phases is pictured on every page of this web site. The old-fashioned image comes from an outdated textbook, but it contains correct information, gleaned from observers' longstanding fascination with the waxing and waning of the Moon.
