Coma Berenices
“Berenice's Hair” · Northern · best around May evenings
Real star positions and magnitudes (HYG database via D3-Celestial, BSD-3). Lines are the conventional stick figure; north is up.
The story
The only constellation honoring a real person: Queen Berenice II of Egypt sacrificed her hair for her husband's safe return (243 BC); the flattering court astronomer placed it in the sky. Its shimmering star cluster really does resemble spilled hair — and behind it opens the Coma galaxy cluster and our galaxy's north pole.
How to find it
The faint shimmer between Leo's tail and Arcturus.
✦ What lives inside it
- Coma star cluster
- Black Eye Galaxy
- The galactic north pole
The deep dive
Researched for the Atlas from Wikipedia — Coma Berenices (23,272 characters read) · updated Sep 20, 2026
01 The only constellation named for a real person
Every other constellation carries the name of a mythological figure, an animal, or an instrument — but Coma Berenices is unique among all 88 modern constellations in being named for an actual historical person. Queen Berenice II of Egypt made a very public vow: if her husband Ptolemy III returned safely from the Third Syrian War, she would sacrifice her famous long hair. Conon of Samos, court astronomer to Ptolemy, turned that sacrifice into astronomy. Modern scholars still debate whether Conon unveiled the asterism before or after Ptolemy's return, but the most detailed reconstruction places the public ceremony sometime between March and June 245 BC. Conon collaborated with the poet and scholar Callimachus on the announcement, framing the vanished tresses as a divine act — Aphrodite herself had gathered them and set them among the stars. The story was so compelling that Catullus translated Callimachus' poem into Latin, and it is from that translation that the constellation's name, Coma Berenices, comes down to us.
02 From asterism to official constellation, step by step
The group of faint stars we now call Coma Berenices spent roughly 1,800 years in an awkward limbo — recognized as an asterism but folded into Leo by influential authorities. Both Eratosthenes and Ptolemy treated it as part of Leo; Ptolemy called it Plokamos in the Almagest and never granted it standalone status among his 48 constellations. The asterism's formal promotion happened gradually during the 16th century. A set of globe gores by Johannes Schöner in 1515 labelled it Trica, meaning simply "hair." Caspar Vopel put it on a celestial globe in 1536, and that same year Petrus Apianus charted it as "Crines Berenices." Gerardus Mercator's 1551 globe gave it no fewer than five Latin and Greek names, and his towering reputation as a cartographer drove Dutch globe-makers to include it from 1589 onward. Tycho Brahe sealed the deal by cataloguing fourteen of its stars in 1602. Johannes Hevelius later raised that count to twenty-one, and John Flamsteed pushed it to forty-three. The International Astronomical Union finally fixed the constellation's boundaries in 1930, when Belgian astronomer Eugène Delporte defined them with a twelve-segment polygon.
03 How the world's cultures saw Berenice's Hair
Long before Greek astronomers formalized the asterism, other cultures had their own names for this patch of sky. The Akkadians called it Ḫegala, and a Babylonian star tentatively identified with the group carries the label ḪÉ.GÁL-a-a, meaning "which is before it." Egyptian Ramesside star clocks may record it as sbꜣw ꜥšꜣw, "many stars." Arabic astronomers knew it by three names — Al-Dafira ("braid"), Al-Hulba ("tuft"), and Al-Thu'aba ("tuft") — though Al-Sufi still placed it within Leo, mirroring Ptolemy. The North American Pawnee people depicted ten faint stars of the group on a tanned elk-skin star map that dates to at least the 17th century. In South American Kalina mythology it was called ombatapo, meaning "face." The Tongan people held four separate names for it: Fatana-lua, Fata-olunga, Fata-lalo, and Kapakau-o-Tafahi. The Boorong people of Australia saw it as a small flock of birds drinking rainwater from a puddle in the crotch of a tree, calling it Tourt-chinboiong-gherra. Few constellations carry such a rich, genuinely global record of observation.
04 Beta Comae Berenices, our near-twin sun Deeper
The constellation's brightest star, Beta Comae Berenices, is an unusually close solar analog sitting just 29.95 ± 0.10 light-years from Earth — so close that it has a notably high proper motion, slowly shifting its position against the background sky over human timescales. Its spectral class is F9.5V B, placing it just a fraction hotter and more massive than the Sun. The numbers are instructive in their nearness: Beta Comae Berenices is about 36% more luminous than the Sun, 15% more massive, and carries a radius only 10% larger. It is classified as a solar analog rather than a true solar twin because those modest differences in brightness and mass push it just beyond the Sun's exact profile. Its Flamsteed number is 43 Comae Berenices, and it sits in the constellation's northeastern region. Alpha Comae Berenices, despite carrying the prestigious Alpha Bayer designation, is actually dimmer at magnitude 4.3 versus Beta's 4.2 — one of the well-known mismatches between Bayer lettering and true brightness rank. Alpha, named Diadem, is a double star composed of two F-type main-sequence stars lying 58.1 ± 0.9 light-years away.
05 The Coma Star Cluster hiding in plain sight
The Coma Star Cluster is one of the sky's great overlooked spectacles. It has been known since antiquity — Ptolemy himself noted it in the Almagest — yet it never received a Messier or NGC designation because it sprawls across more than five degrees of sky, far too wide for the small fields of the telescopes those catalogues were built around. Its official designations are Melotte 111 and Collinder 256. The cluster contains about 50 stars ranging in brightness between magnitudes five and ten, several of which are visible to the naked eye. It looks so large because it is genuinely close: only 280 light-years, or 86 parsecs, from Earth. Gamma Comae Berenices — an orange giant 169 ± 2 light-years away, roughly 10 times the Sun's radius and about 1.79 times its mass — is the cluster's brightest member and serves as one anchor of the three-star triangle from which Berenice's imaginary tresses hang. For observers with binoculars under a dark sky, sweeping slowly through this region on a spring evening is one of the constellation's great pleasures, with dozens of pale stars gradually resolving out of what first appears to be a hazy glow.
06 Dark matter's first address: the Coma Cluster Deeper
When astronomer Fritz Zwicky turned his attention to the Coma Cluster (Abell 1656) in the 1930s, he found that the galaxies inside it were moving far too fast to be held together by the visible matter alone. His calculations led him to postulate the existence of what we now call dark matter — one of the most consequential ideas in the history of cosmology, and it emerged directly from observations of objects in this constellation. The Coma Cluster lies 230 to 300 million light-years away and ranks among the largest known clusters, containing at least 10,000 galaxies, the majority of them elliptical. Its two brightest members, NGC 4874 and NGC 4889, reach only magnitude 13; most cluster members are magnitude 15 or fainter, demanding large telescopes. NGC 4889 harbors one of the largest known black holes, with a mass of 21 billion solar masses. In 2015, researchers identified Dragonfly 44 within the cluster — a massive galaxy whose mass rivals the Milky Way's yet emits only 1% of the Milky Way's light, suggesting it consists almost entirely of dark matter.
07 Record-breakers hiding in one constellation Deeper
Coma Berenices punches well above its weight in astronomical firsts. SN 1940B, discovered on 5 May 1940 in the galaxy NGC 4725, was the first type II supernova ever caught in progress by scientific observation. SN 2005ap, discovered on 3 March 2005, is the second-brightest supernova known to date, reaching a peak absolute magnitude of about −22.7; despite that extraordinary luminosity, its distance of 4.7 billion light-years — roughly a third of the way across the observable universe — kept it invisible to the naked eye. SN 1979C, found in M100, held onto its original X-ray brightness for 25 years even as it faded in visible light, a puzzle that attracted sustained attention. Malin 1, discovered in 1986, was the first giant low-surface-brightness galaxy ever identified. The white dwarf HZ 43 provided the first detected extrasolar source of extreme ultraviolet radiation, found in 1975. And the Coma Berenicids meteor shower, while sparse at only one or two meteors per hour, produces some of the fastest meteors known, hitting the atmosphere at up to 65 kilometres per second.
08 Galaxies that collide, merge, and transform
Coma Berenices offers front-row seats to several galactic collisions caught at different stages. The Black Eye Galaxy (M64, NGC 4826), roughly 17.3 million light-years away, shows the aftermath of an ancient merger: its outer interstellar gas rotates in the opposite direction from its inner regions, a telltale sign that a satellite galaxy collided with it less than a billion years ago. Every trace of the smaller galaxy has been absorbed, but the collision zone between the counter-rotating regions bristles with young nebulae and fresh stars. NGC 4676, nicknamed the Mice Galaxies, is a pair of interacting spirals about 300 million light-years away whose closest approach happened approximately 160 million years ago, triggering intense star formation and pulling out long tails of dust, stars, and gas from each galaxy. Astronomers predict at least one more significant interaction before the two eventually merge into a probably elliptical galaxy. NGC 4651, the Umbrella Galaxy, shows tidal stellar streams gravitationally stripped from a smaller satellite, and lies about 62 million light-years away — on the outskirts of the Virgo Cluster, where tidal forces are still actively reshaping galaxies.
09 Variable stars and what FK Comae revealed Deeper
With over 200 known variable stars, Coma Berenices is rich territory for stellar physics. The most scientifically important is FK Comae Berenices, which oscillates between magnitudes 8.14 and 8.33 on a rapid cycle of just 2.4 days. It is the prototype for the entire FK Comae Berenices class of variable stars and is the star in which the "flip-flop phenomenon" — a sudden shift of a star's dominant active region to the opposite hemisphere — was first discovered. The constellation also hosts 123 RR Lyrae variables, many of them concentrated in the globular cluster M53; one of these, TU Comae Berenices, may be part of a binary system. M100 contains roughly twenty Cepheid variables observed by the Hubble Space Telescope, whose measured periods helped calibrate cosmic distance estimates. FS Comae Berenices is a semi-regular red giant varying between magnitudes 5.3 and 6.1 over a period of about two months, and R Comae Berenices is a Mira variable reaching nearly magnitude 7 at maximum. In 2019, researchers at the Aryabhatta Research Institute of Observational Sciences announced the discovery of 28 new variable stars inside the globular cluster NGC 4147 alone, underscoring how much remains to be found.
10 Gamma-ray bursts, blazars, and the high-energy sky Deeper
Coma Berenices has hosted some of the most energetic transient events ever recorded. GRB 050509B, detected on 9 May 2005, lasted only 0.03 second — but it became the first short-duration gamma-ray burst for which astronomers successfully detected an optical afterglow, a breakthrough that helped confirm the merger-of-compact-objects model for short bursts. GRB 080607, on 7 June 2008, added another high-energy event to the constellation's tally. The blazar W Comae Berenices (also designated ON 231) sits in the constellation's northwest. Originally catalogued as a variable star, it was later identified as a BL Lacertae object — a type of active galactic nucleus with a relativistic jet aimed nearly directly at Earth. As of 2009, it displayed the most intense gamma-ray spectrum among the sixty known gamma-ray blazars. HS 1216+5032 adds yet another exotic object: a gravitationally lensed pair of quasars, their light bent and duplicated by an intervening mass. Together these objects make Coma Berenices a surprisingly productive hunting ground for high-energy astrophysics, despite the constellation's quiet, hair-like appearance in the optical sky.
11 Poets, painters, and a periwig: the cultural life of a constellation
Few constellations have attracted as sustained a creative response as Coma Berenices. Alexander Pope alluded to the Berenice legend at the close of The Rape of the Lock, in which a lock of stolen hair ascends to the stars — and names from that poem would later be applied to moons of Uranus. The Irish poet W. B. Yeats wrote of "Berenice's burning hair / Nailed upon the night." The Swedish poet Gunnar Ekelöf in 1933 placed Berenice's hair hanging down from the sky alongside a comet combing its locks with the Leonids. Russian poet Afanasy Fet devoted a short poem to the constellation in 1892, composed specifically for Countess Natalya Sollogub. In visual art, Spanish painter Luis Ricardo Falero created a mezzotint personifying the constellation in 1886, while Irish artist Alice Maher in 1999 produced four oversize drawings of entwining black hair coils titled Coma Berenices. Spanish composer Francisco Guerrero wrote an orchestral work on the constellation in 1996. Even the constellation's early English names carry a certain charm: before "Coma Berenices" became standard by 1702, speakers called it "Berenice's Bush" and, perhaps most memorably, "Berenice's periwig." The earliest recorded English name, "Berenices haire," dates to 1601.