In the north of the sky, in a region bounded by Ursa Major, Arcturus and the Bowl of Virgo, can be seen what looks like a large, faint star cluster. This is actually the constellation Coma Berenices, given permanent status in 1551 by Gerardus Mercator, from stars previously regarded as belonging to Leo. It supposedly represents the hair of Queen Berenice of Egypt, which she cut off in gratitude to the gods for the safe return of her husband from battle.
Coma Berenices is not a large constellation, yet it contains no less than eight Messier objects. Furthermore, in the background are many galaxies, some brighter than magnitude +10. A good example is NGC 4565, possibly the most prominent of needle-thin edge-on galaxies in the heavens.
NGC 4565, also known as the Needle Galaxy or Caldwell 38, is the largest edge-on spiral galaxy in the night sky. It is quite similar to our Milky Way, although NGC 4565 is slightly more massive (our Galaxy has a mass of about eight hundred billion suns). The Needle Galaxy contains at least two hundred globular clusters and is thought to have a dark matter halo with a mass of several hundred billion suns.
NGC 4565 is located 1.7° east of the star 17 Comae Berenices, and less than 3° from the North Galactic Pole. Through an 8-inch telescope, you will see a streak roughly 10 arcminutes long but only 1.5 arcminutes thick, oriented northwest to southeast. As you increase the telescope’s aperture, the apparent length of the Needle Galaxy also increases. A 16-inch scope shows NGC 4565’s full extent.
A dark dust lane runs the entire length of the galaxy, masking much of the arms’ brightness. The central region features a small bulge, and that is the easiest place to detect the dust lane. The dark streak is offset a little to the north of center because NGC 4565 is inclined to an angle of 87°, 3° from edge-on.
Finder map – field width 15°, stars to magnitude +8.5.