Puppis the Stern, adrift on the Milky Way
earthsky.org
In the southern sky, you can find the constellation Puppis, the Stern. Long ago, it was part of a much larger group called Argo Navis. This giant pattern depicted a famous mythical ship. The French astronomer Nicolas Louis de Lacaille divided Argo Navis into smaller parts in the 1750s, creating three new constellations: Puppis (the Stern), Carina (the Keel), and Vela (the Sails). Puppis is the largest of these new groups; it is the 20th largest constellation in the entire sky. Its vast size reflects the magnitude of the original ship. Now, the Stern drifts across the Milky Way, an area filled with countless stars and fascinating objects.
If you live in the Northern Hemisphere, Puppis can be difficult to see because it lies far to the south. To view the entire constellation, you need to be near 36 degrees north latitude or farther south. Observers north of this line will only see the upper portion. This is fortunate, as that section contains several famous deep-sky objects known as Messier objects. These bright star clusters and nebulae are favorite targets for telescope users.
For northern viewers, the best time to observe Puppis is in March. On a clear night, look low on the southern horizon. From the Southern Hemisphere, Puppis passes almost directly overhead. To locate it, first find Sirius, the brightest star in the night sky. Sirius resides in the constellation Canis Major (the Greater Dog). Puppis is located just to the south-southeast of Canis Major.
The brightest star in Puppis is named Naos, also known as Zeta Puppis. To find Naos, start at Sirius in Canis Major. Imagine a line extending past the dog's tail and continue it for about 15 degrees. This line will point directly to Naos. Naos is a brilliant blue supergiant star with a magnitude of 2.2. Magnitude measures a star's brightness, where a lower number indicates a brighter star. Naos is located approximately 1,400 light-years from Earth.
From Naos, move about 10 degrees toward Canis Major to reach Pi Puppis, also named Ahadi. Ahadi is actually a double star system that shines at magnitude 2.7, making it the second-brightest star in Puppis. It is located about 800 light-years away.
For observers who can only see the northern part of Puppis, the most noticeable star there is Rho Puppis, known by the name Tureis. It shines at magnitude 2.8 and is relatively close, at just 63 light-years away.
Another interesting star is L Puppis. Astronomers classify it as a subgiant star, similar to our sun but nearing the end of its main life cycle. A planet orbits L Puppis at a distance comparable to Earth's orbit around our sun. This system offers a glimpse into a possible future for our own solar system.
Puppis sits in the plane of the Milky Way, meaning it contains many interesting objects. Observers with binoculars or telescopes can enjoy rich star fields. Several bright star clusters are located in its northern half, making them excellent targets for northern observers.
Messier 93 (M93) is an open star cluster with a magnitude of 6.2. Through binoculars, it appears as a faint, fuzzy patch. It is located about 5 degrees from the star Rho Puppis. Astronomers estimate it is approximately 3,600 light-years away.
Messier 46 (M46) lies almost 10 degrees north of M93. It is a dense cluster of faint stars with a magnitude of 6.1. It offers a special bonus for observers: a small planetary nebula called NGC 2438 appears to be part of the cluster. A planetary nebula is a glowing shell of gas ejected from a dying star. Scientists believe this nebula is not actually part of the cluster; rather, it lies in front of the cluster at a distance of about 2,900 light-years. The M46 cluster itself is much farther away, at approximately 5,400 light-years.
Messier 47 (M47) is located very close to M46. It is a brighter and more spread-out open cluster that shines at magnitude 4.4, making it easier to spot in binoculars. M47 is about 1,600 light-years from Earth.
Beyond these famous objects, the star fields of Puppis are worth exploring. Scanning the area with binoculars reveals many other unnamed star clusters.
To summarize, Puppis, the Stern, is a constellation formed by splitting the ancient ship Argo Navis. Now, it drifts along the star-filled band of our galaxy, showcasing many wonders of space. For northern observers, March offers a brief window to see it low on the horizon. It remains a surviving fragment of a once-mighty star ship.