The Hermès Arceau L’Heure De La Lune With ‘Black Sahara’ Meteorite Dial

Generally speaking the moonphase complication is relatively straightforward – you have a cutout on the dial, designed to show how much of the lunar disk is visible in the sky on any given day, and as a rule, it’s relatively small. There are simple moonphase watches with no additional complications, but often the moonphase gets packaged along with other complications like the complete calendar, perpetual calendar, or other astronomical complications. The number of watches that really go big, literally, on the moonphase are relatively rare (Arnold & Son’s perpetual moon is one example) and when the Hermès Arceau L’Heure de la Lune was first introduced in 2018, it definitely went big on the moonphase, and was a correspondingly big hit.

The L’Heure de la Lune is in an Arceau case, which was designed for Hermès by Henri d’Origny in 1978, and the moonphase complication module was designed by complications specialist Jean-François Mojon, who has designed some very exotic complications for clients as varied as de Grisogono, Harry Winston (the Opus X) and MB&F.

The watch has two moonphase disks on it; one disk represents the Moon as seen from the Northern Hemisphere, and the other, the Moon as seen from the Southern Hemisphere (somewhat counterintuitively, the Southern Hemisphere display is at 12:00 and the Northern is at 6:00 although there is absolutely no reason other than long-standing convention that North should be at the top.) Unlike almost all other moonphase complications, the Hermès Arceau L’Heure de la Lune’s moonphase disks do not move. Instead, two orbiting satellite disks rotate across the two moonphase disks. One of the two orbital disks carries the date, and the other, the hour and minute hands. As with the Ressence Type 5 L we looked at earlier this week, the satellites are geared so that they’re always right side up (as you can imagine and again, as with the Ressence, legibility would go right out the window if this were not the case).

The two moonphase disks are slightly different – well, on close examination, actually very different – in terms of what they show. The lower disk representing the view from the Northern Hemisphere is more or less an accurate reproduction of the actual surface of the Moon as seen from the Earth – you can see the conspicuous Mare, or lunar oceans, which are actually solidified lava that flowed many eons ago into basins created by large meteor impacts.

In the above image you can actually see the Sea of Tranquility, which was the site of the Apollo 11 lunar  touchdown in 1969 – it’s roughly adjacent to the number 23 on the date dial. The disk for the Southern Hemisphere doesn’t show a map of the actual lunar surface; instead, it shows a highly stylized and very subtle representation of the mythical winged horse, Pegasus, which has inspired a number of different motifs for Hermès; the design is by Dimitri Rybaltchenko, who has designed scarves for Hermès; his great-great-uncle, Phlippe Ledoux, was one of the most famous designers of Hermès scarves. Pegasus is a little hard to make out at first but you can see its front legs in the picture below, just touching the edge of the time-of-day disk, about halfway between the one and the two.

The Moon does in fact look different when seen from the Northern and Southern Hemispheres. The actual features are the same but the Moon looks inverted when you compare the view from one hemisphere to the other (to help understand why, you can imagine that a person standing upright in Paris is going to look as if they’re standing on their head to someone in Cape Town, and vice versa. Another difference is that the shadow of the Earth appears to move across the lunar disk from right to left as seen from the Northern Hemisphere, and left to right as seen from the Southern.

Above, the Moon as seen from the Northern Hemisphere; below, from the Southern.

The dial is made of meteorite but it’s a slightly unusual take on a meteorite dial. Most watches with meteorite dials use slices taken from iron-nickel meteorites, which are etched with acid to reveal what are called Widmanstätten patterns (named for Count Alois von Beckh Widmannstätten, who described the patterns in 1808). These patterns have a cross-hatched appearance thanks to the extremely large iron crystals in the meteorite – they take millions of years to form as the parent planetoid from which the meteor came gradually and extremely slowly cools. These patterns cannot be reproduced artificially unless you happen to have a crucible with excellent temperature control, and ten million years to kill.

The meteorite which donated the dial to this version (part of a limited edition of 85 pieces, released in 2022) is however not an iron-nickel meteorite. Hermès says the donor meteorite was one they call the Black Sahara, and it looks as if it may be what’s called a chondrite meteorite, which has a granular appearance in cross section (“chondrite” is from the Greek “chondres” meaning sand grain). Prior to the release of this watch, Hermès had already produced an Arceau L’Heure de la Lune with a Black Sahara meteorite dial, as part of a group of five, announced in 2020.

These watches were extremely popular when they were introduced; half a dozen years after the original introduction in 2018, they’re still almost overwhelmingly impressive in size, scope, and general visual impact. The moonphase complication is not a practical complication today, but then again, mechanical watches are not particularly practical either, but it is not for their practicality (at least, not primarily for their practicality) that we love them. A mechanical watch is an appeal to your heart and sense of romance, and the Hermès Arceau L’Heure de la Lune has romance to burn.

See it here