With spring ending and summer just around the corner, let us look at an often-forgotten little constellation and the curious tale of how the herdsman lost his club and adopted two dogs. You can find Canes Venatici (pronounced Vuh-nat-uh-si) nestled between the handle of the Big Dipper and Boötes. When most amateur astronomers think of the constellation, when they think about it all, it is usually as a guidepost to various Messier objects, or for its double star, Cor Caroli. The stars in the constellation are dim, with Cor Caroli clocking in at magnitude 2.9. The second brightest star, Beta Canum Venaticorum is magnitude 4.2. Its small size, combined with New York City light pollution, make it an easy constellation to overlook. Ptolemy also ignored the poor dogs, describing them as unfigured stars in Ursa Major in his Almagest.
Boötes makes his first written appearance in Homer’s The Odyssey and usually appears with a club. Alas, the poor herdsman lost his club in a game of telephone played out over centuries. When Hunayn ibn Ishaq was translating Ptolemy’s Almagest from Greek to Arabic in the 9th century, he took the word club and translated it as kullab, or hook. Two hundred years later, Gerard of Cremona rendered the Arabic translation into Latin, but he also made a mistake – turning kullab into kilab, or dog. At the end of the 17th century, Johannes Hevelius was on a constellation naming spree. Taking inspiration from the texts of the time, he decided to formalize the constellation as the dogs of Boötes, and Canes Venatici was born.
Cor Caroli is a handy star for finding deep space objects, being faintly visible even in light polluted skies. Canes Venatici is home to a surprisingly large number of deep space objects given its diminutive size. In addition to several showcase spring galaxies, it is also home to a glorious globular cluster. Along a line from Alkaid in the handle of the Big Dipper to Cor Caroli, you can find the Whirlpool Galaxy (M51) and the Sunflower Galaxy (M63). Not too far from Cor Caroli itself is the spiral galaxy Messier 94. Midway between Cor Caroli and Phecda, the star at the bottom of the Big Dipper, you can find yet another spiral galaxy, Messier 106. If you draw a line from Cor Caroli to Arcturus, a little past the halfway mark and closer to Arcturus, you will find Messier 3. Were it not for Messier 13, the great globular cluster in Hercules, Messier 3 would be the pre-eminent globular cluster in the spring and summer skies.
All those deep space objects are beautiful in a modestly sized telescope from a dark site. In the city, however, light pollution robs them of their luster. Without the assistance of electronic devices, even a six or eight-inch telescope will rarely show more than a faint smudge. Fortunately for the urban stargazer, there are other beautiful objects as well. The aptly named La Superba is a shockingly red supergiant carbon star named by the 19th-century astronomer Angelo Secchi. If you can see Beta Canum Venaticorum, La Superba lies a third of the way along the path to Alcor and Mizar. If you cannot, aim your binoculars or telescope about a third of the way from Cor Caroli to Megrez in the Big Dipper – the star is unmistakably red in hue. Cor Caroli is also a beautiful double star in its own right – its coloring is subtler than the summer jewel Albireo, and you can resolve the pair in a small telescope or even binoculars.
Cor Caroli also did not receive a proper name until the 1600’s. “The Heart of Charles” was granted its name by Sir Charles Scarborough, the physician to Charles II (there are many Charles in this tale). In continuing with the tradition of historical confusion, it is not clear whether Cor Caroli refers to Charles I or Charles II. Charles I was executed for treason by Oliver Cromwell and company during the English Civil War. Charles I’s heir, Charles II, restored the monarchy to England in 1660 – both men were possible candidates. The (mis)adventures of Charles I and II are also not the only tie Cor Caroli has to royalty. In Chinese astronomy, the enclosure of the Supreme Palace covers Virgo, Coma Berenices, parts of Ursa Major, and Canes Venatici. Within the Supreme Palace, Cor Caroli represents the first of the imperial guards in a grouping of seven stars.
Canes Venatici is one of our smaller constellations, and it lacks a pedigree that dates to antiquity. Even though people overlook Canes Venatici as they arc to Arcturus then spike to Spica, Boötes’ adopted dogs have a lot to offer to the amateur astronomer and the amateur historian alike. Like other, more well-known fixtures of the night sky, it has its own unique story across time and cultures. While it is true that the constellations are fantastic maps to star hop from deep space object to deep space object, the stories and myths behind them are also part of the shared human condition. I hope there is enough here to entice you to look in that celestial neighborhood the next time you head out stargazing. Clear skies!