The Silver Splinter Galaxy (NGC 5907)

The Silver Sliver Galaxy: A Mirror of the Milky Way

The Silver Sliver Galaxy (NGC 891) is a magnificent edge-on spiral galaxy located approximately 30 million light-years away in the constellation Andromeda. While the nearby Andromeda Galaxy (M31) captures most of the headlines, the Silver Sliver is a favorite among astronomers because it provides a perfect "side-on" view of a galaxy that is remarkably similar to our own.

A Cosmic Twin to the Milky Way

If you were to travel millions of light-years away and look back at the Milky Way from the side, it would look almost exactly like the Silver Sliver.

• Size and Luminosity: Both galaxies are of similar scale, spanning roughly 100,000 to 120,000 light-years in diameter.

• The Galactic Bulge: Because we see it edge-on, we can clearly see the central bulge—a thick "heart" of older, yellowish stars—peeking out from above and below the flat disk of the galaxy.

The Interstellar Dust Lane

The most striking feature of NGC 891 is the dark, jagged line that splits the galaxy perfectly in half.

• A River of Soot: This is a massive lane of interstellar dust. It is composed of cold gas and microscopic grains of carbon and silicates that block the light from the stars inside the disk.

• Filamentary "Dust Bunnies": High-resolution images from the Hubble Space Telescope have revealed strange, finger-like filaments of dust reaching out from the disk into the galaxy's halo. Astronomers believe these are caused by supernovae and intense star formation blowing material out of the galactic plane.

The "Outer Limits" Galaxy

The Silver Sliver has a bit of Hollywood history.

• Television Fame: It is occasionally called the "Outer Limits Galaxy" because it appeared in the end credits of the original 1960s television series The Outer Limits.

• Pop Culture: It has also been featured in music, most notably in the track "When Twilight Falls on NGC 891" from the 1974 film Dark Star and a track simply titled "NGC 891" by the electronic music pioneer Edgar Froese.

Galactic Fountains

The Silver Sliver is a primary subject for studying the "galactic fountain" model.

• Starry Rain: When stars explode as supernovae in the disk, they eject hot gas into the surrounding halo. As this gas cools, it condenses and "rains" back down onto the disk, providing fresh fuel for the next generation of stars.

• Evidence in the Halo: The faint tendrils of light and gas detected far above the galaxy's equator are the visible evidence of this ongoing cycle of cosmic recycling.