Martin Braun combines two members of his astronomical family (the Kephalos and the Heliozentric) in this eye-catching, unique watch introduced at the 2009 Baselworld Fair. The original Kephalos model debuted in 2008 and included a brand-new retrograde moon phase. Though the moonphase is no longer a part of this new version, the Kephalos II does include other functions that truly deserve to be called “complications,” among which is Martin Braun’s first annual calendar, which features a retrograde date display.

An annual calendar describes a mechanism that automatically takes into account the varying length of each month, moving to the next month after a shorter 30-day month without having to manually correct the display to reach the “1” of the next month. The date only needs to be corrected once each year, on March 1. The system does automatically correct the date during leap years, meaning that the wearer only has to correct for February on this watch three times in a four-year period.

The Heliozentric was an astronomical complication new to the world of watchmaking in 2004. Martin Braun had set out to display the position of the earth in relation to the sun. It is widely known that our earth moves in an elliptical orbit around the sun and occupies the same position in relation to the sun at the same time each year. Representation of the relationship between the sun and the earth can be resolved in many different ways on a watch dial. One could, for example, have the earth move around the dial on a track system, but Braun felt that he could make the display even more visually intriguing for the watch aficionado. For this reason, Braun set to the task using both advanced mathematics and classic mechanics, creating a gear to generate a curve, or more precisely a cycloid, for the oval. The central sun wheel turns twice per year, and a carrier with three planetary wheels makes an annual revolution, all counterclockwise, with both of the main wheels engaging each other. A symbolic earth located on one of the planetary wheels illustrates the planet’s elliptical orbit. This orbit moves in a counterclockwise direction, as in nature.

Braun amended one physical detail to improve the dial’s optics. The earth rotates around the sun in an elliptical orbit, and the sun is positioned in one of its focuses according to the First Law of Kepler. However, Martin Braun decided to place the sun centrally within the ellipse for aesthetic reasons. “An off-center sun variation really aggravated the dial’s aesthetic visuals,” Braun explains.

The Kephalos II also incorporates what became one of Braun’s signature complications early on in his career: the equation of time, seen here as the border between the calendar and the position of the earth. The equation of time indicates the difference between mean and solar time. A small hand travels across the arched scale to display a difference of up to plus/minus sixteen minutes in relation to the mean time shown by the hour and minute hands. This is a rare complication in watchmaking, and the solution to its mysterious function can only be found in this timepiece. The bearing plate for the Heliozentric system doubles as the equation disk—which precludes it possessing the correct shape—and is thus used as a cam.

The Kephalos II is housed in Martin Braun’s signature case. An impressive 44 mm in diameter, it includes the striking coin-edge case band fans of the brand have come to know and love. The lugs are screwed through to the movement holder inside the case. This safety system avoids shifting inside the movement should the watch be subjected to shock and guarantees that the system can be perfectly centered during assembly. Gaskets underneath the screws also guarantee that the case is water-resistant to a minimum of 50 meters. As with all Martin Braun cases, the bezel is screwed down to prevent it from coming off by accident should the watch be subjected to rougher treatment.

The Martin Braun family of astronomical complications is named for figures from Greek mythology, with the classical legends correlated to classic timepieces. Eos (2001) was the Greek goddess of the sunrise and the matriarch of Martin Braun’s now legendary family. Her child, Boreas (2003), was the Greek god of the north wind. Astraios (2005) was Eos’s husband and the father of her children, including Boreas. In 2008, Kephalos entered the scene. Somewhat of a rascal, Kephalos was Eos’s mythological lover. Now this unique model has been extended to include the earth orbit function of the Heliozentric, which made its debut in 2004, and the equation of time display first seen in the Boreas.