Canes Venatici is a northern constellation near Ursa Major. It is best seen in the spring and summer sky.
History and Mythology
The Hunting Dogs, Canes Venatici, was a grouping named by Polish astronomer Johannes Hevelius in 1690. The two greyhound dogs, Asterion and Chara, are held on leash by Bootes, the Herdsman. They are said to be in pursuit of the northern sky's celestial bears, Ursa Major and Ursa Minor.
Notable Stars
The star Cor Caroli, or Alpha Canum Venaticorum, is the constellation's brightest. Its Latin name means "Charles' Heart" and honors England's King Charles II. It is a beautiful double star with components of magnitude of 2.9 at 5.6, separated by 19 arcseconds. It is part of the collar of Chara, one of the greyhound dogs, and one of the best double stars for small telescopes.
Chara, or Beta Canum Venaticorum, is the second-brightest star in the constellation; its lovely name is a Greek word meaning "joy". Chara's most interesting aspect is its similarity to the Sun. At a distance of 27 light years, Chara provides a good chance to see what the Sun would look like at stellar distances.
Y Canum Venaticorum, called "La Superba" by the Italian astronomer Father Secchi, is one most deeply red-toned "carbon stars" in the sky; its beautiful poppy hue is easy to see in binoculars. Y CVn is a semi-regular variable whose magnitude ranges from 4.8 to 6.4 over a period of roughly 157 days. "Y" is a red supergiant 710 light years away, whose cool atmosphere is rich in carbon molecules.
Clusters, Nebulae, and Galaxies
The globular cluster M 3 lies on the extreme southern boundary of the Canes Venatici. It is one of the most splendid and easily seen globular clusters in the sky. It appears as a fuzzy 6th magnitude star to the unaided eye. When viewed with a 6 inch telescope, some of individual stars are revealed, and in larger telescopes hundreds of individual stars can be resolved. It is 34,000 light years away.
M 51, the famous Whirlpool Galaxy, is close to the northwest boundary of Canes Venatici. This galaxy was the first celestial object observed to have a spiral structure, and is now one of the best known spiral galaxies. It is located at a distance of 23 million light-years.
M 51 appears as two connected galaxies, NGC 5095 and NGC 5194. It is distinguished by a bright nucleus and prominent spiral arms dominated by hot, young, blue stars. In a small telescope, it appears as two fuzzy patches. Larger telescopes are needed to see the spiral structure.
M 63 is a spiral galaxy northeast of Cor Caroli, with a large bright oval surrounding the nucleus. The galaxy appears inclined to our line of sight, with a large, bright nucleus. M 94 is an 8th magnitude spiral galaxy about 16 million light years distant. M 106 is another spiral in Canes Venatici, of 9th magnitude, and about 24 million light years away.
Other prominent galaxies in Canes Venatici which Charles Messier missed include NGC 4214, a 10th magnitude irregular galaxy 13 million light years away; NGC 4244, the Silver Needle galaxy, a 10th magnitude, edge-on spiral galaxy at 6.5 million light years' distance; NGC 4449, a 9th-magnitude irregular galaxy 12 million light years away; and the Whale Galaxy, NGC 4631, a distorted 10th-magnitude edge-on spiral.