The Seiko Astron GPS Solar SSJ027 and SSH157 are 2024 Starry Sky limited editions, but they take different approaches: the SSJ027 is smaller and simpler, while the SSH157 adds dual-time, world-time and chronograph functions in a larger case. This is a comparison of published specifications, not a hands-on wear review.
SSJ027 vs. SSH157 at a glance
| Specification | SSJ027 / SSJ027J1 | SSH157 / SSH157J1 |
|---|---|---|
| Movement | Seiko 3X62 GPS Solar (Seiko-authorized retailer) | Seiko 5X83 GPS Solar (Seiko boutique) |
| Case diameter and thickness | 41.2 × 12.0 mm (Seiko-authorized retailer) | 43.3 × 13.4 mm (Seiko boutique) |
| Case length | 48.6 mm (Seiko-authorized retailer) | 49.5 mm (Seiko boutique) |
| Display and functions | Three hands, date, power-reserve indicator and GPS time-zone/time adjustment | Dual time, world time, day/date, time transfer and 12-hour chronograph in 1/20-second increments |
| Case and bezel | Titanium case; retailer lists titanium bracelet | Titanium case and bracelet; ceramic bezel |
| Crystal and water resistance | Sapphire crystal; 10 bar | Sapphire crystal; 10 bar |
| Limited-edition quantity | 1,500 pieces (Seiko Hungary, 2024) | 1,500 pieces (Seiko Hungary, 2024) |
Which one is smaller?
The SSJ027 is the smaller of the two by the published case measurements: it is 41.2 mm wide and 12 mm thick, compared with 43.3 mm and 13.4 mm for the SSH157. The listed case lengths are 48.6 mm for the SSJ027 and 49.5 mm for the SSH157. Those figures make the SSJ027 the more compact choice on paper, but measurements alone cannot establish how either watch will fit a particular wrist.
What the SSJ027 offers
The SSJ027 uses Seiko’s 3X62 GPS Solar caliber and keeps its display relatively straightforward: three hands, a date display and a power-reserve indicator. Seiko’s published specifications include a perpetual calendar through February 28, 2100, GPS time-zone and time-adjustment reception, an in-flight mode and power-save functions (Seiko-authorized retailer).
Its titanium case and bracelet, sapphire crystal and 10-bar water-resistance rating are listed by the retailer. Seiko Hungary describes the dial as translucent pale blue with geometric star motifs; that is the manufacturer’s design description, not an assessment of how the dial looks or reads in person (Seiko Hungary).
#1 Best Overall
![SEIKO Watch SBXY033 [ASTRON Solar Radio Line Metal Band Men] Shipped from Japan Relased in March 2022](https://m.media-amazon.com/images/I/41yXd-xgoUL._SL160_.jpg)
- Includes individual box, Japanese warranty (1 year), and individual box
- Solar radio wave correction function (receives standard radio waves in Japan, China, USA, Germany, and UK)
- Full auto-calendar function (until December 31, 2099)
- Time difference correction function
- Automatic needle position correction function
What the SSH157 adds
The SSH157 runs on the 5X83 GPS Solar caliber and has a more involved feature set. In addition to dual time and world time, its published functions include day and date, a perpetual calendar, time transfer and a chronograph that measures up to 12 hours in 1/20-second increments (Seiko boutique).
The case is titanium with a ceramic bezel and titanium bracelet; the listed crystal is sapphire and water resistance is 10 bar. Seiko Hungary describes the Starry Sky dial motif and chronograph-subdial layout as part of the design (Seiko Hungary). The added functions also mean a busier display than the SSJ027’s three-hand/date arrangement.
Rank #2
- Since its 1987 launch, the Attesa has delivered dependable performance via expert titanium-processing know-how and innovative chronograph technology, and the latest addition to the collection is no different
- Satellite GPS Timekeeping System with Worldwide Reception Area, World's Fastest Timekeeping Signal Reception Speed From GPS Navigation Satellites - As Quick as 3 Seconds, World Time in 27 Cities (40 Time Zones), 1/20 Second Chronograph Measures up to 24 Hours, Dual Time Zone, Alarm / Day Date, Universal Coordinated Time (UTC) Display, Perpetual Calendar, Daylight Savings Time Indicator, Power Reserve Indicator, Light Level Indicator
- Black Super Titanium with DLC Coating 44.6mm Case
- Anti-Reflective Double Domed Sapphire Crystal
- 100M Water Resistant and Limited Warranty
GPS Solar operation and charging
Both watches use solar power and GPS reception to adjust time. The cited Seiko-authorized product sources describe approximately six months of operation on a full charge and around two years in power-save mode (Seiko boutique; Seiko GPS Solar guidance). These are approximate operating figures, not a guarantee of identical results in every use pattern; charging and GPS reception depend on conditions.
GPS time-zone adjustment does not remove every need for user input. Seiko notes that a manual time-zone selection may be needed after regional or daylight-saving changes (Seiko GPS Solar guidance).
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Rank #3
- Case Size: 39.00 mm, Band Width: 20, Case Thickness: 9.22 mm
- Solar Quartz movement, 316L stainless steel, Index dial type, Date
- Stainless steel bracelet, Butterfly clasp with push-buttons,INTERCHANGEABLE-QUICK-RELEASE-BRACELET closure
- Water-resistant up to a pressure of 10 bar (100 m / 330 ft): suitable for short periods of recreational swimming and showering, but no diving or snorkeling.
- 2 Year International Warranty
How to choose between them
- Choose the SSJ027 if you prefer the smaller published dimensions and a simpler three-hand/date presentation with GPS Solar timekeeping.
- Choose the SSH157 if dual time, world time and the chronograph are useful enough to justify its larger case and more complex dial.
- Compare the dimensions in person if fit is decisive. The published measurements establish their relative size, not comfort, wrist presence or legibility on your wrist.
Limited-edition status and availability
Seiko Hungary reported that each reference was limited to 1,500 pieces and expected arrival in July 2024 (Seiko Hungary, 2024). That describes the original edition size and release timing, not current inventory. Remaining stock and pricing depend on the local market; a retailer’s out-of-stock listing in one country would not establish worldwide availability. Seiko’s current US collection shows newer Astron models but does not list these two in its visible lineup, which likewise does not prove global discontinuation (Seiko US Astron collection).
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
