Phases of the Moon
What do moon phases have to do with American Toolbox? A public service break from our usual mundane articles on guitars, shaving cream, and tools? Hey, that sounds good! Call it an educational message from our sponsors.
Questions submitted to our Contact Page regularly include: 1) Why don’t we ever see the Dark Side Of The Moon? 2) Why does the moon gets bigger and smaller?
It all starts with this: Viewed from the celestial north pole, the motion of Earth, the Moon and their axial rotations are all counter-clockwise.
OK, enough college-talk. Why is there a “Dark Side”? In truth, there is not. As our moon orbits Earth, its “other side” is either bathed in sunlight or hidden in shadow. With a temperature spread of about 500˚F ! Why we never see this further side? In addition to its orbit, our moon also rotates upon its axis. One axial revolution per orbit puts it’s “face” to us at all times. Just as if you held your sweethearts hands at arm’s length, and spun her around yourself. You are the earth and she is the moon. Always facing you.
As far as moon phases go, that’s easier. Perception of moon phase exists through varying degrees of reflected sunlight. That amount of reflected sunlight depends on moon orbit position in relation to Earth and Sun. When the moon is behind us (further from the sun) we see more reflected sunlight. Almost directly behind? Full moon. The easiest part? Data does not vary. No complex star charts. Keep looking up; record what you see in a notebook. Within a few months, it all falls into place.