As the summer heat begins to fade and the nights grow longer, the constellation Triangulum climbs into a favorable position for evening observing. Most backyard astronomers know Triangulum as the home of the famous Messier 33, but the nearby galaxy NGC 925 deserves a closer look, too.
Discovery on September 13, 1784
The light of NGC 925 was first brought into human view by William Herschel as he systematically swept the skies with his telescope.
To the naked eye, the sky where it resided was completely blank. But through his homemade mirror, Herschel was peering at an entirely independent stellar system containing hundreds of billions of suns. What Herschel’s primitive telescope couldn’t quite resolve, modern astrophysics and long-exposure photography eventually laid bare. NGC 925 is beautifully, defiantly asymmetrical.
A Galaxy Off Balance
In a textbook spiral galaxy, the bright, dense nucleus sits directly at the geometric center, serving as a stable anchor for the sweeping arms. But in NGC 925, the central bar of stars looks as though it has been moved to one side. The nucleus sits noticeably displaced from the galaxy’s outer structural frame.
Breaking the Galactic Rules
Countless glowing nurseries of pink hydrogen gas dot its asymmetric arms, marking locations where hot, young stars are blinking into existence.
Normally, a galaxy needs a heavy blanket of gas to spark star birth. If the gas gets too thin, the star factories are supposed to shut down completely. However, data from a scientific study in the year 2000 reveal that NGC 925 ignores these cosmic boundaries.
Researchers discovered that the galaxy continues to churn out brand-new stars at its outermost edges, where the gas is far too thin for star formation to be technically possible. By bypassing these standard rules, NGC 925 acts less like a predictable, neatly organized spiral and more like a lawless irregular galaxy, proving that its star birth is driven by chaotic local conditions.
The next time you point your telescope toward Triangulum, take a moment to look past the usual, famous targets. In the glow of NGC 925, you’ll find a reminder that the universe’s greatest wonders are often the ones that refuse to follow the rules.
My Observations
Observation on December 23, 2025, at 9:35 p.m.
As other backyard astronomers have found, NGC 925’s light is spread out thin, and its surface brightness is low. This makes it a true challenge even for my 8-inch SCT scope from suburban skies. I’m in a Bortle 7-8 area, so city light washes out any resolvable pattern for NGC 925.
Frustrated but not defeated, I fired up the Seestar S50 to let an astrophoto do what my eyes visually couldn’t. After a 71-minute stacked exposure, the smart scope cut right through the light pollution, revealing the galaxy’s subtle, asymmetrical structure.
Key Stats
| Constellation | Triangulum |
| Best Viewing | Autumn |
| Visual Magnitude | +10.1 |
| Absolute Magnitude | -19.9 |
| Distance from Earth | ~30.3 million light-years |
| Diameter | ~91,000 light-years |
| Apparent Size | ~12.0 × 7.0 arcminutes |
| My Viewing Grade | C |
| Designations | NGC 925, UGC 1913, PGC 9332, The Amatha Galaxy |
Sources
Kennicutt, R. C., Jr. (1989). The star formation law in galactic disks. The Astrophysical Journal, 344, 685. https://doi.org/10.1086/167834 Cited by: 2441
Pisano, D. J., Wilcots, E. M., & Elmegreen, B. G. (2000). Structure and star formation in NGC 925. arXiv. https://doi.org/10.1086/301464
Seestar photo by Wayne McGraw