Star Constellation Facts: Coma Berenices

Star Constellation Facts: Coma Berenices

Coma Berenices (“Berenice’s Hair”) is a very faint northern sky constellation that represents the hair of
Berenice II of Egypt, the wife of King Ptolemy III who reigned from 246–222 BC. The constellation’s brightest star, Beta Comae, is a yellow-white subgiant found 30 light years from Earth that shines with an apparent visual magnitude of just 4.32.


Coma Berenices is the night sky’s 42nd largest constellation, and is visible to observers located between +90° and -70° of latitude. In the northern hemisphere it is best seen in the spring time, and from the southern hemisphere in late autumn. The constellation can be found lying between Bootes to the east, and Leo to the west, with other constellations bordering Coma Berenices including Canes Venatici, Ursa Major, and Virgo.

Ursa Major Family

Coma Berenices is a member of the Ursa Major family of constellations, together with Boötes, Camelopardalis, Canes Venatici, Corona Borealis, Draco, Leo Minor, Lynx, Ursa Major and Ursa Minor.


Coma Berenices is the only constellation named after an actual historical person, in this case Queen Berenice II of Egypt, who was married to Ptolemy III Euergetes. During the Third Syrian War (246–241 BC), King Ptolemy III embarked on a hazardous mission of revenge against Seleucus II , the ruler of the Seleucid Empire who had murdered Ptolemy III’s sister and her son. Fearing for her husband’s life, Queen Berenice II prayed to the goddess Aphrodite that if she could bring Ptolemy home to her safely, she would cut off her beautiful long, blonde hair.

Following her husband’s safe return, Queen Berenice made good on her promise and placed her locks in a temple dedicated to Aphrodite. After disappearing the next day, the infuriated king was about to have the temple guards executed when the court astronomer appeased the king by telling him that Aphrodite had loved Berenice’s offering so dearly that she placed it in the sky. Motioning to a group of stars in the night sky, the asterism was subsequently known as Berenice’s Hair.


In the 2nd century AD, the Greek astronomer Ptolemy considered Coma Berenices not a constellation, but an asterism representing the lion’s tail in the constellation of Leo. In fact, it wasn’t until 1536 that German cartographer Caspar Vopel officially promoted it to a constellation, while in 1602, one year after Danish astronomer Tycho Brahe’s death, it was published posthumously in his star catalogue.

Meteor Shower

The Coma Berenicids meteor shower takes place from December 12th to December 23rd, with a peak around January 18th. Producing just one or two meteors per hour, this low intensity shower remained undiscovered until 1959, but does boast some of the fastest meteors at 40mph (65km/s).

Principal Stars

– Beta Comae Berenices, in spite of being a beta star, is the constellation’s brightest star with a visual magnitude of 4.26. This yellow-white subgiant (F9.5V B) is located 29.78 light-years away, and shares a number of similarities with our sun, but is a bit brighter and slightly larger.

– Diadem (Alpha Comae Berenices), the second brightest star in Coma Berenices, is a blue-white subgiant (F5V) found 63 light years from our solar system. It has a visual magnitude of 4.32, although it is in fact a binary system whose stars are of visual magnitudes 5.05 and 5.08. Diadem represents the gem found in Queen Berenice’s crown, and the word itself comes from the Greek word meaning “band.” Even today, the word refers to sovereign’s headband, or a jewelled crown.

– Gamma Comae Berenices, the constellation’s third brightest star, is an orange giant (K1II) around 170 light-years from the Sun with a magnitude of 4.350.

Other stars of interest in the constellation includes the variable star FK Comae Berenices; the double star 24 Comae Berenices; the triple stars 12 Comae Berenices, 17 Comae Berenices, KR Comae Berenices and Struve 1639; the neutron star RBS 1223; and the pulsar PSR B1237+25.

Notable Deep Sky Objects

The constellation contains a number of notable deep sky objects, as well as eight Messier objects, namely the spiral galaxies M64, M88, M98, M99, and M100; the barred spiral galaxy M91; the lenticular galaxy M85; and the globular cluster M53.

The Black Eye Galaxy– The Black Eye Galaxy (M64), also known as Messier 64, is a spiral galaxy around 24 million light-years away of magnitude 9.36. Also known as the Sleeping Beauty Galaxy, this is favorite object amongst beginner astronomers as it can be seen clearly using a small telescope. M64 is also nicknamed the Evil Eye because of its bright center set inside a dark band of dust. Unusual in its nature, it features an outer region of gas that rotates in the opposite direction to the stars and gases in its inner regions.

– Virgo Cluster is a group of galaxies found 60 million light years, of which the northern section is found within the constellation of Coma Berenices. Also known as the Coma–Virgo Cluster, this part contains more than 1300 galaxies, including five Messier galaxies, namely M85, M88, M91, M98, and M100.

– Messier 85 (M85) is a lenticular galaxy found 60 million light-years away, making it one of the furthest of the 110 listed Messier astronomical objects. M85 is about 125,000 light-years wide and has a magnitude of 10.0. It is situated in the northernmost section of the Virgo galaxy cluster, and is interacting with the spiral galaxy 4394, and the elliptical galaxy MCG 3-32-38.

– The Needle Galaxy (NGC 4565) is a popular edge-on spiral galaxies around 42.7 million light-years away that can be seen using a small telescope. It sits directly above the North Galactic Pole, and has a visual magnitude of 10.42.

Other objects of interest in Coma Berenices includes the Coma Star Cluster, which lies 280 light years distant and contains around 40 bright stars; and the Coma Cluster of galaxies, which is around 300 million light years away and contains around 1,000 large and 30,000 smaller galaxies. In the constellation can also be found a physical binary quasar called HS 1216+5032.

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