When the Rolex Day-Date Replica Cosmos was launched last year, I already found it highly appealing. This year, in a new execution with an onyx dial as well as miniature globes crafted in onyx, I find it even more so. Let's look at the underlying mechanism for the Cosmos and the powerful artistic representation of time it achieves. On the dial side of the watch, you'll find the hour and minute indicator in a sub-dial at 12 o'clock. Occupying the main real estate of the dial are two miniature globes. These were crafted in titanium in the regular production model introduced last year, and in onyx for this year's Infinity collection.

The watch uses the

belieres system to set its mechanisms as seen on the back of the case.

The globe on the right represents terrestrial time, while the globe on the left represents celestial or sidereal time. Each of these globes relates to the most ancient ways in which human beings have told time. Terrestrial time relates to how the Earth completes a rotation every day. In fact, the Earth completes a full rotation every 23 hours 56 minutes and four seconds.www.rolexperhot.com But at the same time that it rotates on its own axis, it is orbiting around the sun. Over the course of a day, the Earth moves about one degree along its orbit, which creates an additional four minutes each day, hence we have the 24-hour day here on Earth. (There is, of course, a small overage each year -- which is why we create the leap year every four years at the end of February.)

What is sidereal time? Well, because the Earth is rotating, if we look up at the night sky, we see a rotation of the canopy of stars above. These stars are actually fixed in place and it is our planet that is rotating. Each night, looking up at a specific time, stars will appear in the same location at a given time. Because the Earth completes a full rotation in 23 hours 56 minutes and four seconds, this is the exact length of a sidereal day. Thus this is the time it takes for the sidereal globe on the left of the Cosmos to complete a full rotation while the terrestrial globe takes 24 hours to account for the additional four minutes created by the Earth's rotation around the sun.

Even when the sun is out, the stars are still present overhead; it's just that they are now obscured with light reflecting off our planet and into the sky. What is wonderful about the Rolex Day-Date Replica Cosmos is that it is the first watch that miniaturises these two ancient methods of time-telling and places them side by side in the same watch.

Now I want to discuss some comments I've seen by Internet keyboard warriors stating that the Cosmos is overtly reminiscent to Greubel Forsey's GMT earth. This is incorrect and is based on a superficial observation of both watches without a deeper understanding of their underlying mechanics or purpose. Greubel Forsey's GMT watch, which is also an incredible timepiece,Breitling Avenger Replica is a GMT/world-time watch with indications for local and home time, which are complemented by a beautiful animation on a miniature globe which shows time across locations in the different zones when you align their longitude with the time indicator around the globe. There is also a flat world-time indicator on the back. To be honest, function-wise, the GMT Earth has more to do with Montblanc's very cool Geosphere watch which also has two half-domed miniature representations of Earth for the northern and southern hemispheres, which can be aligned with a time indicator to tell time in all 24 zones at one glance, if you are good with Geography.