The Moon Phase: Degrees Of Complication

Meet The Ultimate Status Symbol

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Remove the back of even the simplest mechanical timepiece and the mechanism you see inside looks impossibly complicated. This mechanism, known as the movement, is typically made up of 200 or more individual parts, most assembled manually in a workshop by someone with very steady hands. Over the next week, we'll be looking at the six complications that represent the height of the horological craft.

The Complications

May 30th - The chronograph, which stops time

May 31st - The power reserve, which tells you how long it will stay running

June 1st - The repeater, which chimes the time

June 2nd - The perpetual calendar, which never needs setting

Today - The moon phase, which tracks the lunar cycle

June 4th - The tourbillon, which defies gravity in a quest for precision

In the first article in this series, we discussed the Moonwatch, that famous chronograph that NASA astronauts took to our nearest celestial neighbor. But in this installment, we’re going to cover a completely different kind of moon watch, one that is more about the Earth’s cycles and the slow march of time. The moon-phase complication connects us to the past, when man was fascinated by the movements of the moon, and it guided his travels, his seasons and ultimately led to the creation of our modern calendar.

Unlike the previous complications we have featured, which were largely utilitarian in nature, a moon-phase watch is whimsical and symbolic. Even its appearance sets it apart from other timepieces, suggesting a character in a children’s book or a Renaissance painting. Moon-phase complications introduce color and painting and soft curves to what is usually an angular mechanical dial. In our modern world, where the moon is, at most, an afterthought, the moon phase provides a subtle connection to our past, to our place in the universe, and it gives us an anachronistic flair. A moon-phase watch peeking out from under a shirtsleeve sets its wearer apart, not unlike wearing a monocle or using a fountain pen, though more practical and socially acceptable.

A moon-phase watch is one that displays the current phase of the moon as you see it in the sky. This is shown graphically on the dial, not with a number or a word or some sort of register but with an actual image of the moon. This is what makes the moon phase so different from other complications and so much fun to own. As the moon travels across the sky, so, too, does the moon in the watch movement, displayed in an aperture on the dial.

Sky watching

To understand the moon-phase complication, you must first understand the phases of the moon itself. A moon phase is the lighted area of the moon visible to us as it makes its way around the Earth. Half of the moon is always illuminated by the sun, but, of course, the movement of the Earth and the moon’s position relative to us means that we are constantly seeing a different view. While true astronomy geeks have many names for the appearance of the moon, from "waxing gibbous" to "waning crescent" and others in between, there are four commonly known phases.

A "new moon" is the point at which the moon and the sun are aligned on the same side of the Earth and there is no moon visible to us. As the moon moves through its monthly cycle, more and more of its surface becomes illuminated. The second phase is known as the "first quarter" when the right-hand side of the visible face is in the sun’s light. Next comes the "full moon" when the entire surface is lit up. Then it moves to the "last quarter" when the left-hand side is visible until it finally goes back to a new moon again.

We look at the complicated design behind the moon-phase complication next...