Maybe it’s because the Seiko Astron is the world’s first GPS solar watch that I have a weak spot for it. From the moment the very first ginormous 47mm version came out, I was sold on the idea of having a watch that connects to the GPS network and gets all its necessary energy from light. In particular, I strongly believe that using a solar-powered quartz movement is the way to go. I know I’m not the only one who hates to deal with battery changes, though my concern for the state of our planet drives my appreciation for non-battery movements even more. Anyway, Seiko has released two new Astron limited editions, the SSH157 and SSJ027. Both use solar-powered movements and are limited to 1,500 units. They are very different, though.

Let’s kick things off with the Seiko Astron GPS Solar 2024 Limited Edition SSH157. The dial of this new model mimics the infinite radiance of the starry sky. That sounds about right for a watch that’s connected to a satellite up in space among the stars, right? The transparent light blue dial’s appearance changes depending on the light hitting it and the viewing angle.

Two new Seiko Astron limited editions: the SSH157 is up first

The original Astron models, like my SAST001, measured 47mm wide and 16mm thick. However, thanks to my watch’s titanium and ceramic construction and its short lugs, it never felt uncomfortable on the wrist. Having said that, the SSH157 wears better thanks to its 43.3 × 49.5 × 13.4mm titanium case, titanium bracelet, and ceramic bezel. There are a couple of nice features about the hardware side of this Astron. First, the titanium case and bracelet have a hard coating to fight off scratches. Second, the case has a low center of gravity, which leads to a very stable watch on the wrist. Other comforting features are the dual-curved sapphire crystal with Seiko’s super-clear coating and the folding clasp with push-button release and quick adjuster.

Seiko Astron SSH157 on wrist

The power of the Seiko caliber 5X83

The solar-powered movements of the Astron have come a long way since the introduction of the technology in 2012. Caliber 5X83 represents the latest and greatest Seiko has to offer in the Astron collection. Among other specs, it has an estimated power reserve of up to six months when fully loaded. And in energy-saving mode, that is approximately two years.

Another cool feature is the chronograph sub-dial at 12, which measures elapsed time in increments of 1/20th of a second. Changing to a new time zone is also quicker than ever before, and the time displayed on the main dial can be switched with the one in the 6 o’clock sub-dial by holding down two buttons for three seconds. The main dial and sub-dial hands will then move simultaneously. This will happen much more quickly than it did with the older 5X53 movement.


And there’s more. Because the movement now charges more efficiently, the dials can be more lavish. That’s why the SSH157 comes with a main dial and sub-dials showing contrasting colors and textures. Things to read on the dial are the main time (of course), the day and date indications, another time zone, and the multi-function sub-dial at 9 o’clock.

Lumibrite on the hands and hour markers make the watch easy to read in darker circumstances, and water pressure to 10 bar should not pose a problem for this new Seiko Astron limited edition. Again, 1,500 pieces of this global release will be available, each with a price of €2,600.

Seiko Astron limited edition SSJ027

Up second is the Seiko Astron SSJ027

The SSJ027 has a much more outspoken case design than the SSH157. The inspiration for the color and texture of the dial is similar, but the movement underneath is different too. First of all, we have the faceted, hard-coated titanium case that measures 41.2mm wide, 48.6mm long, and 12mm thick. Inside it ticks Seiko’s caliber 3X62. By the way, this watch gives off a slight Royal Oak vibe, don’t you think? But that’s only a first impression, I would say. Upon closer inspection, it becomes a Japanese watch all its own.

Anyway, back to the movement. The 3X62 is not a chronograph, so the layout is much cleaner. Besides three central hands and a date window, it has just one sub-dial at 8 o’clock. This indicates whether the movement is receiving a GPS signal, its power reserve, leap-second data, and an in-flight mode to prevent receiving GPS signals during flight. Thankfully, this caliber does have the same six-month power reserve as its more complicated sister movement.

Seiko Astron limited edition SSJ027

A cleaner dial

The less cluttered dial of the SSJ027 leaves much more room for its light blue color to radiate and the structure of the dial to play with the light. And while the dial plays with the light, the movement underneath goes to work with it. You might also want to know that this watch is a perpetual calendar thanks to the quartz technology inside. Finally, black hands and indexes with plenty of Lumibrite all sit under a dual-curved sapphire glass with Seiko’s proprietary super-clear coating.

The watch is light and easy to wear, partially thanks to the well-finished titanium bracelet with a push-button deployant clasp and a quick adjuster. This robust-looking, faceted watch is water resistant to 10 bar (100 meters) and is limited to 1,500 pieces worldwide. At €2,300, the SSJ027 is also €300 less than the more complicated SSH157.

Choosing between the two new Seiko Astron limited editions

Now, which one do you pick? Is it the bigger chronograph version, the SSH157, with its powerful caliber 5X83? Or do you go for the smaller, simpler, and edgier SSJ027? Well, the SSH157’s look is more in line with European watchmaking, meaning it has a case shape that’s not revolutionary. Let me put it this way: the SSH157 looks like a serious watch that can blend in with the mechanical crowd. Yes, the dial is on the exuberant side, but there are quite a few Swiss brands around that do textured light blue dials, so it’s also nothing out of the ordinary. This Astron could very well be someone’s first “serious” watch.

The more angular and edgier SSJ027 is a more pronounced watch. Yes, there are also plenty of Swiss watches with an edgy design, but this Astron looks and feels 100% Japanese. This seems to be for those who already have one or two more standard-looking timepieces and are ready to venture into the world of non-round watches.

Seiko Astron limited edition SSJ027

Which one would I pick? They both wear equally well. Although they’re both larger than 40mm wide, they don’t carry the retro burden of being “too big” due to their modern design and titanium construction. To be frank, I wouldn’t pick the light blue version of this 3X series. Instead, I would go for the SSJ013 with its dark blue dial. It would be between that one and the black-dial SSH151 as I already have a watch with a textured light blue dial.

Tell me, which Astron would you pick out of the two new models, the SSH157 or the SSJ027? Or, like me, would you pick one that has already been out for a while?