NGC 891, the Silver Sliver Galaxy, is a spiral seen almost perfectly edge-on in the constellation Andromeda. A dark dust lane cuts the thin disk from end to end, the same kind of view the Milky Way would offer if we could look back at it from outside.
This portrait, made on 23 September 2026, catches that silver needle against the star field of eastern Andromeda, near the border with Perseus. Light from the disk left the galaxy around the time early apes were appearing on Earth.
The galaxy lies about 27.3 million light-years away (8.4 megaparsecs). NASA/IPAC estimates a diameter of about 130,000 light-years, close to the size of the Milky Way. On the sky the bright disk spans roughly 13.5 by 2.5 arcminutes and shines at about magnitude 10, a faint streak in a small telescope and a sharp edge-on system in a deep exposure. Filaments of dust rise above and below the plane, material driven out of the disk by stars and supernovae.
William Herschel discovered NGC 891 on 6 October 1784. It is also Caldwell 23 and a member of the NGC 1023 group. The nickname Outer Limits Galaxy comes from its appearance in the closing credits of the 1960s series The Outer Limits.
Facts
- Edge-on unbarred spiral in Andromeda, type SA(s)b; also Caldwell 23
- Distance about 27.3 million light-years (8.4 megaparsecs)
- Estimated diameter about 130,000 light-years
- Apparent size 13.5′ × 2.5′; visual magnitude about 10.1
- Discovered by William Herschel on 6 October 1784
- Member of the NGC 1023 group; also called the Outer Limits Galaxy
