A Month of Moon-Watching

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Everyone around the world, on a clear night, can look up and see Earths oldest and most beautiful satellite, the moon. The light it reflects from the sun can cast crisp shadows on Earth at night. The gravitational interaction between the earth and the moon cause entire oceans to swell and fall. It is no great surprise that it has inspired generation after generation of people. Since ancient times, humans have wondered at this great, glowing sphere. It has inspired great poets and scientist alike, and its allure drove humans to leave earth for the very first time. Looking up at it inspires us to think beyond ourselves, our neighborhood, our planet, and to remember the beauty of the vast universe we share with innumerable other planets and moons.

To my own disappointment, I realized that I had never personally taken time to intentionally observe the moon. So on New Year’s Eve, 2019, I decided that I wanted to draw the moon every day during January. The intention was to have a complete “moon chart” by the end of the month, and to perhaps learn a few things along the way. So I pulled out my nature journal, flipped to the next blank page, grabbed a ruler and some pencils, and drew a calendar-like chart that filled the whole page. I traced a circle in each of the thirty-one squares using a tiny cookie cutter; these would be my guide when I drew the moon, so size and shape would remain relatively uniform throughout the month.

I was all set for a month of moon-watching. I spent New Years Day anticipating the moon rise, and prepared my binoculars, tripod, and journal ahead of time. That night I stepped into my back yard and looked up with excitement. The sky was grey. A thick layer of clouds covered the entire sky, and the moon was nowhere to be seen. The month wasn’t off to a great start.

Though I had an underwhelming start, the next week brought clear, crisp nights. Every clear night, I attached my binoculars to my tripod and aimed them towards the moon. At first I used watercolors to illustrate the moon, but I moved on to use white paint or pencils and a black colored pencil to more easily capture the details. Night after night, I became more familiar with the moon and more excited when each night revealed new craters. (The moon was waxing when I began).

Between out-of-town trips and cloudy weather, I missed a night here and there. And though I didn’t get to fill nearly as many squares as I had wanted, I learned whole lot more than I had originally anticipated. Here’s a few things I learned and why I think everyone should go moon-watching.

What I Learned

Some of the things listed below might seem a little obvious, but I believe no observation is too small.

The moon rises at a different time each night. It didn’t take me very long to realize that I had to stay up later and later to see the moon. Eventually, I started waking up early the next morning to draw the previous nights moon. Because of the difference between the speed of the moons orbit around earth (about 27 days) and the speed of the earths rotation (24 hours), the moon appears at different times each day to an observer on earth. I attempted to explain this by making this simplistic diagram.

The animation spans seven earth rotations (days), and shows the observer experiencing moon-rise at a different time each day. On the first night, the moon rises at 8pm, and by the seventh day it rises at 9pm. This isn’t entirely consistent with actual earth-moon timing, but I hope it illustrates the concept effectively.

The face of the moon wobbles. I had always heard that we only ever see one side of the moon from earth. Thats why I was surprised when, on about the second full week of drawing the moon, I noticed that some of my landmarks had moved. In the photo below, I took a few moon drawings from my journal page and circled certain dark spots that clearly show rotation. An interesting note, that I just noticed looking at these photos, is that it rotates in both directions, both clockwise and counterclockwise.

I’m not really sure why this happens, but I think it might involve the angle at which we see the moon and (again) the difference in rotation/orbit speed between the earth and the moon. Here’s an incredible video that beautifully illustrates moon wobbles.

The moon is really far away. Okay, this one is a bit too obvious, isn’t it? Well, yes, but also no. I always knew that the moon was “really far away” (about 238,900 miles from earth), but the great distance didn’t quite click for me until one night while I was moon-watching. My sister stepped across the yard from me and pointed to the moon. I pointed as well. When I saw her I had to do a double take, because it looked like she was pointing in an entirely different direction than me. I realized that we were both pointing at the the moon, but because of the immense distance between the earth and the moon, our lines of view appeared to be parallel. It’s like an extremely tall triangle; At the base, both of the arms appear parallel. But at some very far point, they do, in fact, intersect. The base of our “triangle” was so short (less than twenty feet), and both of the “arms” were so long, that it appeared we were pointing to entirely different objects in the sky. I was very pleased to apply my math skills (yay!) to explain what had happened.

The path of the moon across the sky changes. Every night, the moons path was slightly different than what it had been the night before. To my frustration, the moon eventually didn’t even rise far enough above the horizon for me to see it between the buildings and trees surrounding my house. I think this might have to do with my location on earth, and thus the angle at which I look out into space. If I were on the equator, would the moons path change, or remain consistent? Does the moon orbit around the equator, or at a different angle? I’ll have to do some more research to find answers to these questions, but that’s what learning is all about, right?

You can see the dark side of the moon (sometimes). Well, this isn’t quite right. The term “the dark side of the moon” generally refers to the side that always faces away from earth. But here I’m using the term to refer to the side of the moon that’s in shadow, the side that isn’t lit up directly by the sun. While moon-watching, I was dazzled when I noticed that during dusk I was able to see craters and other details on the dark side of the moon. This is because at dusk it is still early enough for light from the sun to hit your side of earth and late enough for the moon to be clearly visible. At this time, light from the sun reflects off of earth and onto the face of the moon, illuminating the shadows. It’s a somewhat magical sight!

The moon became a companion to me over these thirty-one days. After one of the bad weeks, where I had literally no view of the moon for five days in a row, I looked out a window to see a tiny glowing crescent floating behind a tree. It was as if I was reunited with an old friend. This experience was invaluable to me as an aspiring scientist, and I hope to do another month of moon-watching during the summer, as I missed nearly half of January due to cloud cover. I highly recommend that anyone remotely interested in the moon, space, cyclical events, or anything nature-related go moon-watching. Dedicating even a small amount of time to intentionally observe something that interests you will pay off big-time. The more you observe, the more you’ll notice, and the more you’ll learn.

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