An unremarkable constellation holds surprise delights, including bright galaxies and one of the best globular clusters in the sky.
Canes Venatici the Hunting Dogs is a constellation that is hard to see but easy to find. It's available for viewing the majority of the year in the Northern Hemisphere, situated right under the handle of the Big Dipper.
The only bright star of note in the constellation is named Cor Caroli. The 2.89 magnitude star is the first bright star you will see under the tail of Ursa Major, or the handle of the Big Dipper. Cor Caroli lies 110 light-years away. The star is a visual double, with a magnitude 5.61 star lying just 19 arcseconds from it. But the distance measurement to the other star is 81 light-years, meaning that the two are not physically related, but merely a line-of-sight coincidence.
Thirteen degrees east of Cor Caroli lies M3, one of the most beautiful globular clusters in the sky. At magnitude 6.4, the cluster can be captured easily in binoculars and looks spectacular through even a small telescope. A globular cluster is a spherical collection of old stars that orbits the Milky Way Galaxy (or any galaxy) in its halo, or periphery. M3 contains about half a million stars and lies 33,900 light-years away, which is farther away from us than the center of the Milky Way Galaxy is.
Slightly dimmer but at much greater distance than M3 are the four other Messier objects in Canes Venatici.
The first galaxy, M51, is a well-known galaxy nicknamed the Whirlpool Galaxy. It lies 10 degrees north of Cor Caroli. At magnitude 8.4, the Whirlpool is a spiral galaxy that has a small companion galaxy (NGC 5195) that appears to be situated at the end of one of the spiral arms. The galaxy lies about 37 million light-years away but can be seen easily in a smaller telescope from a dark-sky site. See if you can make out its spiral arms and companion.
The second galaxy, M63, is a spiral lying halfway between Cor Caroli and the Whirlpool Galaxy. M63, nicknamed the Sunflower Galaxy, is the dimmest of the four galaxies in Canes Venatici, but it still comes in at magnitude 8.6. It is part of a physical group with M51 and also lies 37 million light-years away.
The third galaxy, M94, lies 3 degrees northwest of Cor Caroli. Its distance is still a matter of debate, spanning a wide range of probabilities between 14 and 33 million light-years. M94 is a spiral galaxy with a very bright core, bringing its magnitude to 8.19.
The fourth galaxy, M106, is a magnitude 8.3 spiral with bright knots of star formation in its arms. At a distance of about 23 million light-years, it lies farther from the last two, in the corner of Canes Venatici and closer to the bowl of the Big Dipper. It is 7 degrees from the bowl star Phecda or 11 degrees from Cor Caroli, on a line between the Big Bear and Hunting Dogs stars.
