#AdlerWall 04: Look Up and Sketch the Moon

by Shane L. Larson

You and I live in the future. Our world is one where information is transmitted instantly to everyone, blasting out of large flat screens and small hand-held devices owned by a billion humans around the globe. Information comes in small blurts of text, a few funny pictures, and now and then in a short video. Electronic memory, captured forever in the ephemeral electronic nothingness of the internets.

It is hard to remember that there was a time, not so long ago, where moving pictures were a marvel, a wondrous example of the technological age that was just beginning to expand its blanket across our civilization. That by-gone age that introduced the world to moving pictures is usually called the “Silent Film Era” and spanned more than 3 decades, from 1894 until the late 1920s when “the talkies” began to take over. In the midst of this age of wonder, an ingenious filmmaker made his trade in France, experimenting with all manner of ways of filming and editing to take his audiences on journeys of imagination and wonder. His name was Georges Méliès, and in 1902 he released one of the great classics of film: Le Voyage dans la Lune — “A Trip to the Moon.”

Inspired by the novels of Jules Verne and H.G. Wells, Méliès imagined making a voyage across the cosmic gulf to visit our celestial companion. This was in the days before rockets — Méliès imagined sending a space capsule to the Moon after launching it from an enormous cannon, a perhaps not unreasonable idea given Newton’s cannonball diagram in his De mundi systemate to describe orbits!

The Moon at that time was a great mystery to us, the target of much speculation and many wild imaginings. Méliès’ vision built on that — the Moon was an alien landscape, populated by alien cultures that his explorers did not understand nor appreciate. It was perhaps an obvious target for Méliès’ imaginings. More than any other place in the solar system, the Moon is a place that we can all imagine visiting, if for no other reason than we can see it with the unaided eye.

Today, more than a century after Méliès’ voyage of imagination, the Moon is a known place. Like many worlds in the solar system, we have photographed it up close and mapped its surface in exquisite detail. But it still holds a certain mystique that other celestial destinations do not. Mostly because we can see it with the unaided eye, but more because it is the only other place in the Cosmos, besides Earth, where human beings have walked. It is a great wonder to step outside and see the distant orb of the Moon riding high in the sky, and know that people just like you once walked there. It still makes me a little breathless, and encourages me to look for the Moon every time I walk out the door. It seems unlikely that I will ever get to walk the craggy lunar landscape myself, so I fall back on the next best thing: I try to see what I can see with my own eyes.

The #AdlerWall exhorts us to “Look up and sketch the Moon.” Most of us have seen the Moon, probably unconsciously the way we notice trees, flowers and other ordinary, everyday things. Part of the Wall’s desire for you is simply to be cognizant of noticing what you are seeing (in the same spirit of our earlier exploration in looking closely at what is under rocks). But the other part of the imperative is the sketching.

Why should we do that? Personally, I’m probably the world’s worst sketcher, but I do it anyhow. Sketching, no matter how crude and rudimentary, helps you notice things. There are many different sketching exercises that you can do, and all of them will bring the Moon a bit closer to you.  Let’s explore some of those ideas together.

Right now, picture the Moon in your mind. What does it look like? Without getting up to look at it, without pulling up a picture of it, make a crude sketch of what you see in your mind’s eye on the back of an old cell phone bill.

What did you draw? Perhaps you drew patchy patterns of light and dark. The variations in brightness across the face of the Moon are caused by the geology that shaped it. The darker areas are called maria, or lunar seas. They are basaltic lowlands, the youngest surfaces on the Moon created by vast lava flows in an earlier, active phase of the Moon’s life. The brighter areas are called terrae, the lunar highlands. These jumbled and broken landscapes are the older parts of the lunar crust, covered with craters and criss-crossed by mountain ranges, escarpments, and vast rilles.

Did you draw any craters? How about mountains? The understanding that such features are found on the surface of the Moon is almost ubiquitous. But unless you have looked at the Moon through a telescope, you probably have never seen a crater for yourself.  You cannot see any craters or mountains on the Moon with your naked eye. Until the time of Galileo, it was widely believed the surface of the Moon was smooth.

Now go out and make a sketch of the Moon, whatever phase it might be in. The patterns of light and dark are the same ones that have been seen by 40,000 generations of humans before us. The surface of the Moon is millions of years old, changing on slow geologic timescales — human lives, and indeed all of human history, are the merest flashes of an instant in the long history of the planets in the solar system. The face of the Moon you see today is the only one ever seen by humans.

Whenever we look at the sky we project all manner of human interests and problems on the sky, a manifestation of our deep and abiding desire to be part of the Cosmos. The Moon is no different than the rest of the sky in this regard. As our most prominent neighbor, it has oft been the target of imaginative musings. There is a long tradition of recognizing and naming patterns in the patchwork of light and dark — moonshadows.

The most famous of the moonshadows is the Man in the Moon, but if you look closely you can also see the Bunny in the Moon, and the Woman with the Pearl Necklace. Can you make up your own moonshadows that you can easily recognize and teach others to see?

The fact that you know the Moon is covered in craters and mountains and canyons is a testament to our civilization’s ability to share knowledge. But in reality, you can discover for yourself exactly what Galileo discovered, even if you don’t own an astronomical telescope. Common birding binoculars or small spotting scopes are all much better than Galileo’s first telescope, and will show you the wonders of the Moon.

You can turn your small scope or binoculars on the Moon at any time, but it is easiest to see surface features when there are strong shadows. This happens at any time during the month except near Full Moon (though you should certainly look at the Moon when it is full!). The boundary between the light and dark on the lunar surface is called the terminator — it is the dividing line between day and night on the surface of the Moon. The shadows of craters and mountains are strongest on the terminator, and if you focus your attention there, you can see some fantastic topography. If you’re inclined to carefully record the shadows you see, some simple mathematical investigations with geometry can be used to figure out how tall and wide the mountains and craters are.

If you look at Galileo’s classic sketches of the Moon, you may notice that he sketches the entire Moon. In your own viewings, especially during the crescent phases, you can often see the faint outline of the dark part of the Moon; through a telescope, you will see fleeting, ghostlike impressions of craters, lunar seas, and mountains in the ephemeral shadows. What is going on here?

This phenomenon is called “Earthshine” — sunlight hits the Earth, bounces off the Earth, and hits the dark side of the Moon, making it appear in ghostly shadows. This is the same effect that lets you see things in the shade of a tree at the park — light from the sunny parts of the park bounces off of everything and illuminates the parts of the park in shadow. The first person to explain the origin of this shadowy illumination of the Moon by Earth was Leonardo da Vinici, in his famous notebook, the Codex Leicester.

Even if you don’t want to sketch the craters and the mountains, even if you don’t want to peer at the Moon through a telescope or binoculars, you may still see the Moon in striking moments of beauty, framed by life here on Earth. A common experience many of us have had is witnessing a Moonrise or a Moonset against the landscape or against the skyline of the city. In many instances you get the overwhelming perception that the Moon is enormous, looking over the Earth like a gigantic cauldron of boiling light, waiting to pour itself out across the landscape.

This apparent enlarging of the Moon is an optical illusion known as the “Moon illusion.” While you can generically break the illusion by disrupting your normal viewing of the scene (try standing on your head, or looking at it upside down), the existence of the illusion does not diminish the awe-inspiring effect it has on your mind’s eye. Somewhat surprisingly, simply taking a picture often destroys the illusion — unless cropped very closely around the Moon, pictures flatten the perspective and bring peripheral parts of the scene into play, destroying whatever visual queues your brain was using to make the Moon look big. It’s weird.

The Moon, like the Sun and stars, is one of the dependable denizens of the sky. Sometimes it is up during the day, sometimes it is up at night. It is constantly changing its shape, and adds majesty and brilliance as a backdrop to images of life on Earth. So the next time you’re out take a look around for the Moon; if you have a moment, snap a picture or make a quick sketch, so you can remember it.  See you out in the world — I’m the guy looking dumbstruck on the street corner, craning his head to see the Moon rising behind the city skyline! 🙂

—————————————-

This post is part of an ongoing series about the #AdlerWall. I encourage you to follow along with the activities, and post your adventures, questions and discoveries on social media using the hashtag #AdlerWall.  Links to the entire series are here at the first post of the #AdlerWall Series.