Caldwell 26

Not to be confused with the Needle galaxy (Caldwell 38), Caldwell 26 is often called the Silver Needle galaxy. The Silver Needle is a spiral galaxy that spans about 65,000 light-years across and lies over 13 million light-years from Earth toward the Canes Venatici constellation. It is a member of the M94 group, which is a small collection of galaxies that is part of the same galactic supercluster as the Milky Way.

While it’s one of hundreds of billions of galaxies in the universe, the Silver Needle’s strange appearance sets it apart. Most spiral galaxies have a Saturn-like shape, with a spherical central bulge surrounded by a relatively flat disk (both of which are surrounded by a “halo” of old stars). As this Hubble image shows, however, the Silver Needle is extremely thin. The galaxy’s central bulge is much less pronounced than we see in most spiral galaxies and its halo is very faint.

This cosmic oddity’s spiral arms are not visible since we see the galaxy edge-on, but its orientation and diminutive central bulge make the galaxy’s halo easier to study. Hubble’s observations of the Silver Needle, taken in visible and infrared light by the Advanced Camera for Surveys, were part of the Galaxy Halos, Outer disks, Substructure, Thick disks and Star clusters (GHOSTS) survey to look at the fossil record preserved in the resolved stellar populations of local galaxies. The survey has yielded significant advances in the study of galaxy assembly and evolution.

The Silver Needle was discovered by astronomer William Herschel in 1787 and is also cataloged as NGC 4244. It is best viewed from the Northern Hemisphere during spring (autumn in the Southern Hemisphere), away from city lights, though even then it will be difficult to spot in small telescopes. In larger telescopes, the magnitude-10.4 galaxy will appear like a thin, silvery splinter cutting through the sky.

For more information about Hubble’s observations of Caldwell 26, see:
A Silver Needle in the Sky

Galactic Bulge - A dense collection of stars at the center of a spiral galaxy, possibly hosting a supermassive black hole.

Galactic Halo - A roughly spherical collection of old stars and globular clusters surrounding a spiral galaxy.

Magnitude - The brightness of an astronomical object, represented by a number; bright objects have low numbers on the magnitude scale, while dim objects have high numbers.

Spiral Galaxy - A galaxy characterized by its spiral structure, with star-filled arms that extend out from the center of the galaxy and host regions of star formation.