Watching the Moon
I was in my twenties before I realized the moon rose at a different time every night.
I had gone to Ko Pang Nan in Thailand for their famous full moon party. I arrived a couple of days before the party. The almost-full tropical moon was the brightest I had yet experienced in my life — I remember walking along the beach at night, amazed at how dark and crisp the shadows were, able to see faint hints of color because the moonlight was so bright.
The full moon party happened and was a bit of a letdown. Turns out bar hopping is bar hopping, no matter where in the world I am. A couple nights later it was about ten o’clock and I realized there was no moon. I said something about it and the Thai guy who owned the place I was staying at told me the moon rose later and later every night, then pointed out the blood-red moon low on the horizon.
I was floored. How could I have lived so many years and never noticed the pattern of the moon rising? Did they teach it in school and I somehow missed that class?
From that day on, I started noticing the moon’s patterns, and this is what I discovered:
When the moon is full, it rises when the sun sets and sets when the sun rises.
It rises about an hour later every day, so the three nights after full moon are the best times for watching the moon rise.
By the time the moon is rising at midnight, it’s half-full.
Once the moon is smaller than half-full and waning, I rarely see it unless I wake up early enough in the morning that it’s still dark.
At new moon, the moon rises and sets with the sun.
A day or two after new moon, I’ll see the moon for the first time in over a week, as a crescent moon that sets soon after the sun sets.
When the moon is half-full, it rises around noon and it’s midway through its path of rising to setting in the sky when the sun sets; in the tropics this means it’s directly overhead, whereas in Alaska it can still be low on the horizon, the way the winter sun is low on the horizon at noon. The moon will set around midnight when it’s half-full.
The waxing moon rises later and later until it becomes full and rises when the sun sets, and the pattern repeats itself.
At first it seemed like a miraculous coincidence that the sun was always setting when the full moon was rising, then I realized that’s why the moon was full; same for the half-moons being directly overhead at midnight or noon, or the new moon rising and setting with the sun. My observations have never caught the moon breaking this pattern, whether the days are long in summer or short in winter.
One application of my observations has been to estimate the time from the moon’s position in the sky compared to its phase; another has been to know when it will be easy to see at night, and when it will be darker. I enjoy checking up on authors when I’m reading a story — some authors understand the moon, and have a military raid time their operations around a waxing moon setting in the wee hours of the morning, whereas other authors have no clue and have a full moon that hasn’t risen yet even though it’s already midnight on Earth.
Another fun thing to notice when moon watching is that the path the moon makes in the sky is six months off from the path the sun makes. So if you’re planting a garden in summer and want to see which new plants are going to be shaded in winter, you can go out at night and see where the moon casts its shadows.
I’m so grateful I happened to run across that Thai man who clued me into the patterns of the moon; I could have gone my whole life and never understood why sometimes I saw the moon in the blue sky, sometimes briefly as a crescent, and sometimes not at all for days on end. Understanding the moon helps me feel privy to a great mystery of life; even though it’s just science and astronomy, it still feels magical to me.
