Coma Berenices, meaning “Berenice’s Hair,” is a faint northern constellation with an unusual distinction: it is named after a real historical queen rather than a mythological character or animal. Although its brightest stars are only around fourth magnitude, Coma Berenices contains a wealth of astronomical objects, including the beautiful Coma Star Cluster, the Black Eye Galaxy (M64), and the Needle Galaxy (NGC 4565). It also lies in a region of the sky filled with distant galaxies.
Covering approximately 386 square degrees, Coma Berenices is the 42nd-largest of the 88 recognized constellations.
Where and When to Find Coma Berenices
Coma Berenices is best observed from the Northern Hemisphere during spring, particularly from March through May. The constellation lies between Leo to the west and Boötes to the east, with Virgo to the south. To locate it, first identify the bright star Arcturus in Boötes and Denebola, which marks the tail of Leo. Coma Berenices occupies the relatively faint region of sky between them.
Unlike constellations with striking star patterns, Coma Berenices is more easily recognized by the loose scattering of stars that forms the Coma Star Cluster. Under dark skies, this cluster appears as a delicate sprinkling of faint stars, resembling the flowing hair that gave the constellation its name.
Mythology — The Hair of Queen Berenice
Coma Berenices is associated with Berenice II, queen of Egypt and wife of Ptolemy III Euergetes, who ruled during the third century BC. According to the traditional story, Berenice feared for her husband’s safety when he departed on a military campaign. She promised the goddess Aphrodite that she would sacrifice her beautiful hair if he returned safely. When Ptolemy came home, Berenice fulfilled her vow by cutting off her hair and placing it in a temple.
The offering subsequently disappeared, causing considerable alarm at the royal court. The astronomer Conon of Samos reportedly explained that the goddess had accepted the gift and placed Berenice’s hair among the stars. The story became famous in ancient poetry and gave the constellation its enduring name.
History
The stars of Coma Berenices were known in antiquity, although they were not originally recognized as an independent constellation. Ptolemy associated the region with Leo in his second-century star catalog. The constellation gradually became established in European astronomy during the 16th century and appeared in later star catalogs and celestial atlases. Today, Coma Berenices is one of the 88 officially recognized constellations.
Notable Stars
- Beta Comae Berenices is the constellation’s brightest star, shining at approximately magnitude +4.3. Located around 30 light-years away, it is a yellow-white main-sequence star that is slightly hotter and more luminous than the Sun.
- Diadem (Alpha Comae Berenices) is a binary star system approximately 60 light-years away, with a combined apparent magnitude of around +4.3. Its name refers to a jeweled headband or crown, recalling Queen Berenice.
- Gamma Comae Berenices is an orange giant shining at approximately magnitude +4.4. Located around 170 light-years away, it lies near the Coma Star Cluster and provides a useful landmark for locating the group.
- 24 Comae Berenices is a colorful double star that appears yellow-orange and blue-white through a small telescope. It is a popular target for amateur observers because of the contrasting colors of its components.
Notable Deep-Sky Objects
Coma Star Cluster (Melotte 111)
The Coma Star Cluster, also known as Melotte 111, is one of the closest open star clusters to Earth, located approximately 280 light-years away. It contains dozens of stars spread across an unusually large area of sky, covering roughly five degrees. Because the cluster is so widely scattered, binoculars generally provide a better view than a telescope. Under dark skies, several of its brighter stars can also be seen without optical aid. The cluster is a particularly attractive springtime target and is one of the easiest ways to identify Coma Berenices.
Black Eye Galaxy (M64)
The Black Eye Galaxy (Messier 64, NGC 4826) is a spiral galaxy approximately 17 million light-years away, shining at around magnitude +8.5. It is famous for the dark band of dust crossing the bright region near its nucleus, creating the appearance of a black eye.
M64 is also known as the Sleeping Beauty Galaxy or Evil Eye Galaxy. Astronomers have discovered unusual motions within the galaxy’s gas, including regions that rotate in different directions. These features may be evidence of a past interaction or merger with another galaxy. A small telescope can reveal M64 as a faint oval glow, while larger instruments under dark skies may show its distinctive dust feature.
Needle Galaxy (NGC 4565)
The Needle Galaxy (NGC 4565) is one of the finest examples of an edge-on spiral galaxy visible through amateur telescopes. Located roughly 30–50 million light-years away, it appears as a long, narrow streak of light with a prominent dark dust lane running across its disk. Its thin appearance results from viewing the galaxy almost directly from the side. Under good conditions, a moderate-sized telescope reveals its elongated shape, making it a rewarding target for observers interested in distant galaxies.
Messier 53
Messier 53 (NGC 5024) is a globular star cluster approximately 60,000 light-years away. Shining at around magnitude +7.7, it appears as a small, rounded glow through binoculars or a small telescope. Larger instruments begin to resolve its densely packed stars. It lies relatively close to Diadem, making it one of the easier deep-sky objects to locate in Coma Berenices.
The Virgo Cluster and Coma Cluster
Coma Berenices is particularly rich in galaxies because it looks toward two important concentrations of galaxies at very different distances.
The Virgo Cluster, approximately 55 million light-years away, extends across the boundary between Virgo and Coma Berenices. Several Messier galaxies in Coma Berenices, including M85, M88, M91, M98, M99, and M100, belong to this wider region.
Much farther away lies the Coma Cluster (Abell 1656), approximately 320 million light-years distant. It contains more than a thousand galaxies and is one of the most extensively studied galaxy clusters.
The two clusters should not be confused: the Coma Cluster is a separate, much more distant system.
Observing Coma Berenices
Coma Berenices is an excellent spring constellation for observers interested in star clusters and galaxies. Begin with the Coma Star Cluster, which is best appreciated through binoculars. Then use a telescope to explore M53 and the Black Eye Galaxy. More experienced observers can search for the Needle Galaxy and the many faint galaxies scattered throughout this region of the sky.
Although its stars are modest, Coma Berenices offers some of the richest deep-sky observing opportunities of the spring sky.