Under the Green Desk Lamp…
I got a strange phone call the other day. A friend of mine phoned to point out that he could see both the sun and the moon in the sky at the same time.
Certainly, there was nothing unusual about this other than his desire to call and tell me about it. But—he then pointed out—the moon had a shadow on it.
He didn’t need to say anything more; I saw the problem immediately.
All my young life, I’d grown up with the simple understanding that the dark spot or ‘shadow’ on the moon was caused by the Earth blocking out some of the light from the sun—essentially throwing its own shadow across the moon and hiding part of it from our sight.
I remembered—I was certain—elementary school teachers explaining this concept to us in great detail—likely using plasticine models, and perhaps a flashlight. It was, at any rate, a scientific ‘fact’ I had taken as sacrosanct my entire life.
In that one phone call, the idea was demolished entirely.
If I could see both the sun and the moon, that meant the sun had a direct line to the moon—unobstructed by the selfish machinations of the Earth. Therefore, the shadow across the surface of the moon could not possibly be caused by the Earth, as I had always understood.
Suddenly, everything I thought I had known about the lunar cycle was in shambles. This may seem like a small loss to anyone who gives even an average amount of consideration to the nature of celestial bodies, but I have a particular affinity for the sanctity of knowledge, and I found it quite troubling indeed.
Immediately, I set off to correct my false understandings and learn the truth about this now mysterious phenomenon. It took no time at all, and my understandings were soon corrected to incorporate this newfound information,. But I was nevertheless left with an unpleasant taste in my mouth.
Asking around over the following weeks, I soon discovered—to my small comfort—that I was far from alone in my naïve misunderstandings—in fact, I could scarcely find any other person who knew the truth about how the lunar cycles worked.
No, probably not.
But you thought you did.
Most everyone I talked to thought the shadows on the moon were created by the Earth—just as I had so very recently. Simple fools!
The truth is, you see, that the dark spot on the moon is caused not by the Earth, but by the moon itself. Depending on the moon’s position relative to the sun, one half of it will always be fully lit (the side facing the sun), and one half will be dark (the side opposite the sun). The lunar cycle we witness is a product of the angle at which we view it. If the Earth is between the sun and moon, we will look back at it and see it fully illuminated. If the Earth is behind the sun and moon, we will see little of it, as we look towards its unlit side.
Finally, it the moon is somewhere between those extremes, we will see part of its illuminated side, and part of its dark side—as was the case on the day in question. (Source).
Once again, the function of the lunar cycle made sense. The world was right again.
…or was it?
No. Not quite. In the end, I was left questioning far more than just the moon. I’d been so confidant in this understanding. In fact, I would have likely gone so far as to say I ‘knew’ how it all worked. How then could I now remain confident in anything else I thought I knew, upon learning firsthand the fleeting transience of my knowledge?
It made me think of the nature of knowledge itself, and how much of what we claim to know is truly only suspected, or worse still, believed. It spoke to me of information bias and the ubiquity with which we cling to false truths.
Socrates once asked, “Can we ever truly ‘know’ anything?”
No, I suppose we cannot.
-Brad OH Inc.
Thanks for ruining the rest of my Sunday while a review planetary movements…ARG!
Happy to help DC!