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NGC 891 – the Milky Way’s mirror galaxy

Hidden among the northern constellations of the autumn sky lies a galaxy that, while less famous than Andromeda, is just as fascinating to astronomers: NGC 891. Seen almost perfectly edge-on, this spiral galaxy has earned the nickname “the Milky Way’s twin”, as it shares many of our galaxy’s fundamental properties.

🌌 A neighbor beyond the Local Group

NGC 891 is located at a distance of roughly 30 million light-years, in the constellation of Andromeda. Although it is not part of the Local Group, it belongs to the nearby cosmic neighborhood, close enough to allow highly detailed observations of its structure.

Its nearly edge-on orientation makes NGC 891 an exceptional object for studying the vertical anatomy of a spiral galaxy.

📸 Images from LilTecan

The LilTecan team has photographed the galaxy NGC 253 in different wavelengths to highlight the richness of detail in its morphology.

NGC891 LRGB+Ha+O[III]

🌟 A large, calm, and familiar spiral

Unlike extremely active galaxies, NGC 891 is a massive spiral with a moderate rate of star formation, very similar to our own Milky Way:

  • It has an extended stellar disk crossed by a thick, dark dust lane.
  • Its star-formation rate is comparable to that of the Milky Way.
  • It hosts a mixed population of young and old stars, typical of mature spiral galaxies.

This apparent “normality” is precisely what makes it so valuable for science.

🌫️ Dust, gas… and an unexpected halo

Such intense activity comes at a cost. Supernovae and massive stars generate powerful galactic winds thOne of the most intriguing aspects of NGC 891 is that dust and gas are not confined to the galactic disk:

  • Infrared and radio observations have revealed dust filaments rising thousands of light-years above the disk plane.
  • A halo of cold and hot gas has been detected, likely powered by supernovae and stellar winds.
  • These findings help us understand how galaxies exchange matter between their disks and their surroundings.

NGC 891 shows that spiral galaxies are dynamic, three-dimensional systems—not just flat disks.

🔭 A laboratory for understanding our own galaxy

Because we observe the Milky Way from within, many of its structural details are difficult to study directly. NGC 891, offering an almost perfect external view, acts as an observational reference model:

  • It allows astronomers to study the vertical distribution of stars, gas, and dust.
  • It helps investigate the presence and role of dark matter in spiral galaxies.
  • It provides a benchmark for testing models of galactic evolution in a system very similar to our own.

In a very real sense, observing NGC 891 is like seeing the Milky Way from the outside.