Coma Berenices Constellation – Home of 8 Messier Objects

In this article, we’ll be sharing with you everything you need to know about the constellation of Coma Berenices, including how to find it, deep space objects contained within it, and how to use it to find other night sky objects more easily.

The Constellation of Coma Berenices

When Greek astronomer Ptolemy cataloged the constellation of Leo over 2,000 years ago, the stars that we know as Coma Berenices formed the tuft of the lion’s tail.

In 1536, cartographer Caspar Vopel mapped Coma Berenices as a new constellation on his globe and in 1602, Danish astronomer Tycho Brahe listed it in his star catalog.

This modern constellation is associated with a historic person and Greek mythology: Queen Berenice II and her lock of golden hair.

Queen Berenice II (ca. 267–221 BC) was the daughter of King Magas of Cyrene and wife of Ptolemy III Euergetes (ruler of Egypt).

When King Ptolemy III went on a dangerous mission against the Assyrians, Queen Berenice II vowed to sacrifice her beautiful blonde hair if her husband returned safety. King Ptolemy III did return and Queen Berenice II cut off her hair and placed it in Aphrodite’s temple.

When Queen Berenice II’s hair disappeared from the temple, Conon (the court astronomer) announced that Aphrodite placed it in the sky so that everyone could see it.

In Latin “Coma Berenices” means “Berenice’s hair”.

To help you spot Coma Berenices, here’s how SkySafari 6 shows the queen’s hair. Notice stars from Boötes constellation to the left (e.g. Tau Boo) and from Leo in the bottom right.

The queen's hair which is the symbol for Coma Berenices constellation
Coma Berenices constellation as its mythical image. Click for full-screen

Coma Berenices has an area of 386 square degrees making it the 42nd largest of the 88 recognized constellations.

Coma Berenices has a distinct right-angle appearance, which makes it look like half of a square cut diagonally.

For such a small part of the sky, a lot is going on! For example, it is known amongst astronomers for its star and galaxy clusters.

The Coma Star Cluster contains ~40 stars, resembles a tuft of hair, and is one of the best binocular objects in the night sky. See more about that towards the end of this page.

The northern part of the Virgo Cluster of galaxies is contained within the borders of Coma Berenices, and Messiers 85, 88, 91, 99, and 100 are part of that Cluster.

The North Galactic Pole (the north pole of the Milky Way) is also in Coma Berenices at right ascension 12h 51m 26s and declination 27° 07′ 42″ (J2000.0).

Location of the north galactic pole within Coma Berenices
The North Galactic Pole (NGP) is in Coma Berenices; the galactic grid is also shown. Click for full-screen

In the next section discover how to find Coma Berenices.

How To Find Coma Berenices In The Night Sky

Coma Berenices is part of the Ursa Major family of constellations and is visible to observers at latitudes between +90° and -70°.

Northern Hemisphere observers can see it in evening skies from January to August. It is almost overhead for mid-northern latitude observers in April and May. Southern Hemisphere stargazers can see it from March to June.

The constellation of Coma Berenices is bordered by the constellations Boötes, Canes Venatici, Leo, Ursa Major, and Virgo.

Showing the five constellations bordering Coma Berenices
Constellations bordering Coma Berenices. Click for full-screen

To find Coma Berenices, do a naked-eye search for the star Zosma, in Leo. Draw an imaginary line ~40° east to Arcturus, in Boötes. Alpha Comae Berenices is at the midpoint of this line.

Alternatively, do a naked-eye search for Phecda in the Big Dipper and connect it to Spica in Virgo with an imaginary line running north-south for 67°. Coma Berenices is midway along that line.

See the SkySafari 6 chart below for more guidance. You can measure these distances with your hand at arm’s length.

Star chart showing how to find Coma Berenices constellation.
Finding Coma Berenices using the surrounding constellations. Click for full-screen.

To find Coma Berenices’s exact position for your location on any night, use software such as Stellarium (free) or SkySafari 6.

The Brightest Stars in Coma Berenices

Coma Berenices is a small constellation with no stars brighter than magnitude 4. The following list describes some of the more interesting ones. Use the star chart below to identify where to find them.

Star chart showing all the stars brighter than magnitude 5.0 in Coma Berenices
Star chart showing all the stars brighter than magnitude 5.0 in Coma Berenices. Click for full-screen.

Alpha Comae Berenices (Diadem) – This variable double star is the second brightest star in Coma Berenices, Beta is actually a fraction brighter.

The magnitude 4.32 yellow-white main-sequence primary and its magnitude 11.45 secondary component are 0.3 arcseconds apart. This is already too close to split in a backyard telescope, but they get even closer over their 26-year orbit.

Diadem, meaning ‘jeweled crown in the hair’ is an eruptive variable ranging in magnitude from 4.29 to 4.35 and it’s 65 light-years away.

Beta Comae Berenices – This double star is the brightest in Coma Berenices and marks the ‘corner’ of the constellation. It consists of a yellow main-sequence primary shining at magnitude 4.25, and a magnitude 12.10 secondary component which is 126.5 arcseconds away.

This system is 29.9 light-years away from Earth.

Gamma Comae Berenices – This double star is the third brightest star in Coma Berenices and is 167 light-years away.

The orange giant primary star has a magnitude of 4.34, while the secondary shines at magnitude 12.00. The two stars are 16.1 arcseconds apart.

24 Comae Berenices – This variable double star is 450 light-years away. The magnitude 4.98 orange giant primary and magnitude 6.33 secondary components are 20.4 arcseconds apart.

This is an eruptive variable ranging in magnitude from 4.98 to 5.06.

35 Comae Berenices – This double star is 283 light-years away. The yellow-orange primary is a giant star shining at magnitude 4.92, its secondary shines at magntidue 7.08 magnitude.

The two components are only 1.2 arcseconds apart.

Star Hopping From Coma Berenices

Coma Berenices’ dim stars make it a poor starting place for star hopping.

Objects To See Within Coma Berenices

Coma Berenices contains eight Messier objects and a few other deep sky objects suitable for small telescope users.

M53 (NGC 5024) – This globular cluster has a magnitude of 7.61 and an apparent size of 13.0 arcminutes. It’s 1° northeast of the star Diadem and 58,000 light-years away from us. Find it at right ascension 13h 12m 55s and declination 18° 10’ 05” (J2000.0).

M64 (NGC 4826, Black Eye Galaxy) – This spiral galaxy has a magnitude of 8.38 and an apparent size of 10.5 x 5.3 arcminutes. It’s 14 million light-years away and is at right ascension 12h 56m 43s and declination 21° 40’ 55”.

M85 (NGC 4382) – This spiral galaxy has a magnitude of 9.04 and an apparent size of 7.0 x 5.3 arcminutes. It’s 58 million light-years away and is at right ascension 12h 25m 24s and declination 18° 11’ 25”.

These are the easiest galaxies to see in a backyard telescope

M88 (NGC 4501) – This spiral galaxy on the boundary with Virgo is part of the Virgo Cluster of Galaxies. It has a magnitude of 9.36 and an apparent size of 8.7 x 4.4 arcminutes. It’s 65 million light-years away and is at right ascension 12h 31m 59s and declination 14° 25’ 12”.

M91 (NGC 4548) – This spiral galaxy has a magnitude of 10.05 and an apparent size of 5.5 x 4.5 arcminutes. It’s 51 million light-years away and is at right ascension 12h 35m 26s and declination 14° 29’ 46”.

M98 (NGC 4192) – This spiral galaxy has a magnitude of 9.93 and an apparent size of 11.0 x 2.7 arcminutes. It’s 41 million light-years away and is at right ascension 12h 13m 48s and declination 14° 54’ 00”.

M99 (NGC 4254, Coma Pinwheel Galaxy, Pinwheel Galaxy) – This spiral galaxy has a magnitude of 9.72 and an apparent size of 5.0 x 4.7 arcminutes. It’s 42 million light-years away and is at right ascension 12h 18m 49s and declination 14° 25’ 00”.

M100 (NGC 4321) – This spiral galaxy has a magnitude of 9.30 and an apparent size of 6.1 x 5.6 arcminutes. It’s 52 million light-years away and is at right ascension 12h 22m 55s and declination 15° 49’ 20”.

NGC 4147 – This globular cluster has a magnitude of 10.31 and an apparent size of 4.4 arcminutes. It’s 63,000 light-years away and is at right ascension 12h 10m 06s and declination 18° 32’ 34”.

NGC 4565 (Needle Galaxy) – This spiral galaxy has a magnitude of 9.08 and an apparent size of 16.8 x 2.9 arcminutes. It’s 39 million light-years away and is at right ascension 12h 36m 20s and declination 25° 59’ 15”.

Melotte 111 (Coma Star Cluster) – This huge open cluster has a magnitude of 1.79 and an apparent size of 120.0 arcminutes. It’s 313 light-years away and is at right ascension 12h 25m 06s and declination 26° 16’ 30”

Summary

Coma Berenices is a dim, medium-sized constellation containing very few notable stars but a lot of deep sky objects for small telescope users.

Hop on over from Leo this spring or summer and count how many of its galaxies and star clusters you can find.


Written by Tanya C. Forde