Observing the Constellation Puppis
Canopus, Other Stars and Clusters in the Stern
The large constellation of Puppis the Stern lies low in the South and contains Canopus and three of Messier's star clusters.
The constellation of Puppis was once part of a much larger constellation named Argo Navis. This former ship was divided into four constellations named after parts of the ship. They are Puppis the Stern (or Poop), Carina the Keel, Vela the Sail, and Pyxis the Compass.
Locating the Constellation Puppis
Puppis is far enough south that the entire constellation cannot be seen unless you live around Nashville's latitude or farther south. However, people north of here can see the northern portion of the constellation, which happens to contain three Messier objects.
Puppis is best viewed in winter after it rises in the south-southeast. It lies behind and below the form of Canis Major the Big Dog, which itself lies below the more notable constellation Orion.
The Stars of Puppis the Stern
Focusing on Sirius, the brightest star in the sky and found in Canis Major, trace a line from here down the Dog's back past his hind star and tail star and then straight out toward a star 13 and a half degrees away that is similar in brightness to the last two. This star is the brightest in Puppis, the magnitude 2.21 Zeta Puppis. It lies 1,400 light-years away from Earth and behind it swims the Milky Way.
Heading nine and a half degrees back in the direction of Canis Major toward its hind legs is another 2nd magnitude star, Pi Puppis. Pi Puppis is magnitude 2.71 and lies 1,094 light-years away.
Very low to the horizon and only visible to more southerly observers is the magnitude 2.94 star Tau Puppis, 183 light-years away. It lies just four and a half degrees from Canopus in the constellation Carina. Canopus is the second brightest star in all the sky.
There is only one 2nd magnitude star in the top half of the constellation Puppis. You can find it lying about 11 degrees away from the brighter hind stars in Canis Major. This star is Rho Puppis. It shines at magnitude 2.83 from a distance of 63 light-years.
Star Clusters in Puppis
Puppis lies right on the Milky Way, which affords it some sparking star clusters cataloged by Messier. All the star clusters are found in the north half of the constellation, making them visible to most residents in the United States. The first star cluster is found five degrees from Rho Puppis, toward Canis Major. This cluster is M93, shining at magnitude 6.2. This grouping lies about 3,600 light-years from Earth.
The next two clusters are nine and a half degrees north of M93. They are M46 and 47 and they lie about one degree apart. M47 is the one closer to Canis Major. M46 is magnitude 6.1 and includes a bonus object, a small nebula. The nebula is believed to be a foreground object that just coincidentally appears to be a part of the cluster. The nebula is given its own designation of NGC 2438 and is of 10th magnitude. M46 is roughly categorized as lying 5,400 light-years distant and NGC 2438 is believed to be 2,900 light-years away.
Next door, M47 is a brighter star cluster at magnitude 4.4. About 1,600 light-years away, its brighter stars make it appear under good sky conditions without optical aid.
Puppis is a great location to simply sweep the sky slowly with binoculars or a telescope and look for additional clusters. Its position on the Milky Way gives it a regular polka-dotted appearance with NGC named clusters occurring every few degrees in the sky.
