High overhead in the spring lies Coma Berenices, a lesser-known constellation depicting the golden hair of Queen Berenice II of Egypt. As the story goes, Berenice had offered her beloved hair as an offering to the goddess Aphrodite for the safe return of her husband Ptolemy III Euergetes, who was off fighting in a war. When Ptolemy returned safely, Berenice kept her promise.
Ptolemy went the following day to see his wife’s offering but found the hair missing. Enraged that it had been stolen, he was calmed by the court astrologer Conon of Samos who informed him that Berenice’s offering had been taken by the gods. That night, Conon pointed to a grouping of stars high in the sky, explaining that the gods were so pleased by the offering that they placed Berenice’s hair in the heavens.
A little over two millennia later, Coma Berenices is recognized as one of the official 88 constellations.
Spring and fall are some of the best times to view our galactic neighbors as the bright band of our own Milky Way galaxy is lower in the sky. Coma Berenices is home to quite a few prominent galaxies, including a large group called the Coma Cluster.
One of the many photogenic spiral galaxies available to backyard telescopes under dark skies is NGC 4565, also known as Caldwell 38 or the Needle Galaxy. Spiral galaxies like the Needle and the Milky Way are giant disks of stars, gas and dust.
Galaxies can be tilted in different directions. Imagine throwing a handful of coins in the air. They would be oriented in random directions: some would appear face-on, a few would be edge on, but most would be tilted at some angle.
We see the same thing when we observe galaxies in our universe. In the cases of the Needle Galaxy and our Milky Way, we are viewing them from the side so they appear very elongated. Galaxies such as the Whirlpool Galaxy (M51) are seen face-on and appear very round, while others such as Bode’s Galaxy (M81) are at varying angles so they appear a bit squashed.
Though we cannot clearly see the spiral structure of the Needle in visible light, its shape and the presence of blue stars and thick clouds of dust betray its true nature. The dark band that runs across the middle of the galaxy is a prominent dust lane that obscures the visible light of stars behind it. The blue tint seen especially well toward the Needle’s “points” is due to the very luminous, hot, blue stars.
Spiral galaxies contain the necessary ingredients to form new stars, namely cold gas to build the stars and dust clouds that provide shielding cocoons. The luminous blue stars are very massive, and massive stars live very short lives. The presence of these stars within the Needle implies recent and ongoing star formation.
Careful inspection of the galaxy’s edge-on disk will show that it is not perfectly flat — there is a slight warp to its shape. This is most likely due to gravitational interactions with nearby galaxies, and studies indicate the warp likely formed around 130 million years ago.
The edge-on view also shows another hallmark of spiral galaxies — a central bulge. In most of the galaxy, stars move in the same direction to form a flat disk. But near the center, they move in many different directions, creating a brighter, fuzzy-looking area. Panoramic shots of our own Milky Way show the band of the galaxy bulging out around its core in the constellation of Sagittarius.
If you are out observing the Needle Galaxy, take some time to try to catch a few of the other impressive galaxies that call Coma Berenices home including the Black Eye Galaxy (M64), which owes its memorable name to a very prominent dust lane, and the gorgeous face-on spiral galaxy NGC 4321 (M100).
If you happen to have really dark skies, a decent-sized telescope and some patience, you will come across quite a few other fuzzy “stars” — these are just some of the many other spiral and elliptical galaxies you’ll find hanging out in this part of the sky. Happy hunting!